Signal amplifier device, a means of transport comprising a signal amplifier device, and a method for operating a signal amplifier device

Abstract

A signal amplifier device for amplifying signals in a wireless communication network, wherein the signal amplifier device comprises at least one first antenna for communicating with a mobile device and at least one second antenna for communicating with a base station, wherein the signal amplifier device provides a signal path for electrically connecting the at least one first antenna to the at least one second antenna for transmitting uplink and downlink signals, wherein the signal path is at least partially divided into a first downlink signal path and a first uplink signal path, wherein the signal amplifier device comprises at least one downlink amplifier for amplifying a downlink signal and at least one uplink amplifier for amplifying an uplink signal,wherein the at least one downlink amplifier is arranged in the first downlink signal path and wherein the at least one uplink amplifier is arranged in the first uplink signal path. The signal amplifier device comprises at least one first downlink power detector for detecting a downlink signal power. The signal amplifier device comprises a bypass line for directly electrically connecting the at least one first antenna to the at least one second antenna. The signal amplifier device also comprises a control unit configured to receive a measured value from the at least one first downlink power detector. The control unit is further configured to activate the bypass line when the measured value of the downlink signal power from the at least one first downlink power detector exceeds a first limit value.so that the signal amplifier device switches from the normal operating mode to the bypass mode, wherein the at least one downlink amplifier and the at least one uplink amplifier are electrically separated from the respective at least one first antenna and at least one second antenna when the bypass line is activated.

Description

DECLARATION CONCERNING FEDERALLY FUNDED RESEARCH OR DEVELOPMENT

[0001] No. FIELD OF THE INVENTION

[0002] The technology described here relates to an amplifier for mobile communications and in particular to a method for operating such an amplifier. BACKGROUND

[0003] An amplifier is used to amplify wireless communication signals. Specifically, a signal amplifier is a device that automatically receives, amplifies, and retransmits signals received from base stations, fixed stations, mobile stations, or portable stations on a bidirectional or unidirectional basis without changing the frequency or authorized bandwidth.

[0004] Such signal amplifiers are used in transportation vehicles, such as cars, trains, etc. However, the use of signal amplifiers is not limited to transportation vehicles. They can also be used in buildings, for example. Signal amplifiers comprise a first antenna and a second antenna, wherein the first antenna is arranged inside the transportation vehicle and wherein the second antenna is arranged on the outside of the transportation vehicle. The first antenna is used to transmit and receive communication signals from and to a mobile device, wherein the second antenna is used to transmit and receive communication signals from and to a base station. Thus, the mobile device is connected to the base station via the amplifier.It is extremely advantageous that the mobile device's transmission power is significantly below the maximum transmission power, which simultaneously ensures a stable connection between the mobile device and the base station. This connection is independent of any interference from any electromagnetic shielding that the transport vehicle may contain.

[0005] In general, a repeater is also a type of signal amplifier. However, a repeater is capable of amplifying a signal with significantly higher gain than a signal amplifier.

[0006] Unfortunately, the use of a signal booster can cause interference with cellular systems. This interference may not be limited to the network the booster is using, but can also spread to other neighboring networks. A power overload situation may occur. As a result, other devices may become disconnected. A signal booster can also increase the noise floor, which reduces the sensitivity of the base station and thus reduces the coverage area of all devices. This can also lead to poor reception at the base station, preventing a mobile device from establishing communication at all.

[0007] Measures to prevent these malfunctions include avoiding excessive noise. To obtain approval to operate a signal booster, the FCC (Federal Communications Commission) has issued guidelines that every booster device must adhere to. Reference is made to FCC Title 47, Chapter I, Subchapter B, Part 20, §§ 20 and 21 (Signal Boosters), dated February 11, 2015, which is incorporated herein by reference.

[0008] Furthermore, US 2018 / 041 234 A1 discloses a signal amplification device that adjusts the gain between two antennas by changing an amplification factor. Furthermore, US 2018 / 138 967 A1 discloses a signal amplifier that provides a wireless charging option for mobile devices.

[0009] The FCC requires that a signal booster device meet the limits for noise and gain. Otherwise, it must operate in a "transmit power off mode," in which at least the uplink booster is disabled (i.e., turned off). In this case, the uplink booster has an attenuation of more than 30 dB. If the signal booster device is installed in a vehicle, the attenuation is high due to the materials used in the vehicle's body, but is typically less than 30 dB. Therefore, the mobile device communicates directly with the base station.

[0010] Therefore, the problem addressed here is to describe and / or provide a signal amplifier device and method for meeting the FCC requirements with respect to signal amplifiers in a reliable and reproducible manner, while still providing a stable communication link even when the signal amplifier device cannot be operated in a normal operating mode due to excessive noise. Summary of the invention

[0011] The problem is solved with a signal amplifier device and a method for operating a signal amplifier device. Furthermore, a means of transport comprising such a signal amplifier device is shown. Advantageous, non-limiting implementations of the signal amplifier device are specified in the subclaims.

[0012] The signal amplifier device is used to amplify signals in a wireless communication network. Therefore, the signal amplifier device comprises at least one first antenna for communicating with a mobile device and at least one second antenna for communicating with a base station. The signal amplifier device also provides a signal path for electrically connecting the at least one first antenna to the at least one second antenna for transmitting uplink and downlink signals. The signal path is at least partially divided into a first downlink signal path and a first uplink signal path. Furthermore, the signal amplifier device comprises at least one downlink amplifier for amplifying a downlink signal and at least one uplink amplifier for amplifying an uplink signal.The at least one downlink amplifier is arranged in the first downlink signal path, and the at least one uplink amplifier is arranged in the first uplink signal path. The signal amplifier device also comprises at least one first downlink power detector for detecting a downlink signal power. The signal amplifier device further comprises a bypass line for electrically connecting the at least one first antenna directly to the at least one second antenna. Furthermore, a control unit is arranged in the signal amplifier device and configured to receive a measured value from the at least one first downlink power detector.The control unit is further configured to activate the bypass line when the measured value of the downlink signal power from the at least one first downlink power detector exceeds a first threshold value, so that the signal amplifier device switches from the normal operating mode to the bypass mode. In the bypass mode, the at least one downlink amplifier and the at least one uplink amplifier are electrically isolated from the at least one first antenna and the at least one second antenna.

[0013] It is highly advantageous for the signal amplifier device to include a bypass line, directly connecting the antennas. Such a bypass line has lower attenuation (i.e., 4 or 5 dB) than the vehicle body. Consequently, after the uplink amplifier is deactivated due to high noise, the signal amplifier device switches to bypass mode by releasing the bypass line. The mobile device continues to transmit its signal to the at least one first antenna of the signal amplifier device. This antenna is now directly electrically connected (i.e., without any amplifier) to the at least one second antenna mounted on the exterior of the vehicle. When using the bypass line, the attenuation of the communication signal transmitted or received by the mobile device is lower than attenuation due to the vehicle body itself.Therefore, the base station is not overloaded with noise and the mobile device continues to have a "good" connection to the base station compared to all the signal booster devices available on the market that do not use a bypass line but instead only disable the uplink booster.

[0014] Using the bypass line when the downlink signal power exceeds the first threshold also reduces the overall signal power at the at least one downlink amplifier. As a result, it is possible to use less expensive low-noise amplifiers as downlink amplifiers that are not designed for high power levels.

[0015] According to a further aspect of the present invention, the signal amplifier device in bypass mode frequently checks whether the bypass line is still required or whether the signal amplifier device can return to normal operating mode. This is done by periodically reconnecting the antenna to the amplifiers. However, such a connection is preferably only established for the period necessary to obtain a new measured value for the downlink signal power. After obtaining the measured value, the antennas are reconnected via the bypass line. This is particularly true if the downlink signal power continues to be higher than the first threshold. Alternatively, the antennas remain connected to the amplifiers if the newly obtained measured value has fallen below a second threshold, which may be the same as or lower than the first threshold.In general, the period for which the antennas are reconnected to the amplifiers to obtain new measurement results is shorter than the period for which the antennas are connected to each other using the bypass line when the signal amplifier device is in bypass mode.

[0016] According to another aspect of the present invention, the first uplink signal path and / or the first downlink signal path are divided into at least two uplink and / or at least two downlink branches. While the first uplink signal path and the first downlink signal path can be used to transmit communication signals belonging to different mobile radio bands, only one mobile radio band is transmitted via each of the respective branches. An additional amplifier is arranged in each branch, thereby enabling different mobile radio bands to be amplified differently.

[0017] According to a further aspect of the present invention, the signal path is also split into a second downlink signal path and a second uplink signal path. The first uplink path and the first downlink path are used to provide a signal path for a low frequency band, thereby allowing the transmission of different mobile radio bands in the low frequency band. The second uplink path and the second downlink path are used to provide a signal path for a high frequency band, thereby allowing the transmission of different mobile radio bands in the high frequency band. The distinction between a low frequency band and a high frequency band is extremely advantageous because the mobile radio bands belonging to the same low frequency band or high frequency band can be amplified together, thereby achieving better results.

[0018] Furthermore, a means of transport according to the present invention is also described here. The means of transport comprises a signal amplifier device as described above, wherein the at least one first antenna is arranged inside (inside) the means of transport and wherein the at least one second antenna is arranged on the outside of the means of transport. The means of transport can be, but is not limited to, a motor vehicle, a ship, a train, or an aircraft.

[0019] Finally, a method for amplifying signals in a signal amplifier device is also described here. The signal amplifier device comprises at least one first antenna for communicating with a mobile device and at least one second antenna for communicating with a base station. The signal amplifier device thereby provides a signal path for electrically connecting the at least one first antenna to the at least one second antenna for transmitting uplink and downlink signals. The signal amplifier device also comprises at least one downlink amplifier for amplifying a downlink signal and at least one uplink amplifier for amplifying an uplink signal. The signal amplifier device comprises at least one first downlink power detector for detecting a downlink signal power.Furthermore, the signal amplifier device comprises a bypass line for electrically connecting the at least one first antenna directly to the at least one second antenna. The signal amplifier device further comprises a control unit configured to receive a measured value from the at least one first downlink power detector, wherein the control unit is configured to activate and deactivate the bypass line. The method comprises the following steps for amplifying signals in a signal amplifier device: Obtaining a measured value from the at least one first downlink power detector, Determining whether the measured value of the at least one first downlink power detector exceeds a first limit value, Switching from the normal operating mode to the bypass mode when the measured value of the at least one first downlink power detector exceeds the first limit value, whereby the at least one downlink amplifier and the at least one uplink amplifier are electrically isolated from the respective at least one first antenna and the at least one second antenna, respectively.

[0020] Various non-limiting embodiments are described in detail below by way of example with reference to the drawings. Like items have the same reference numerals. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The following detailed description of exemplary, non-limiting illustrative embodiments should be read in conjunction with the drawings, in which Fig. 1A - 1D: show block diagrams of a signal amplifier device according to various embodiments of the present invention; Fig. 2A and Fig. 2B: show various block diagrams of an embodiment of a first uplink signal path and a first downlink signal path; Fig. 3A - 3C: show various block diagrams of an embodiment of a first and a second uplink signal path and a first and a second downlink signal path; Fig. 4: shows a diagram explaining how the gain of the signal amplifier device according to the present invention is adjusted with respect to the RSSI; Fig. 5: shows a diagram explaining the periodic switching between the second switching state and the first switching state when the signal amplifier device is in bypass mode; and Fig. 6: shows a flowchart explaining a method of the present invention for operating the signal amplifier device. DETAILED DESCRIPTION OF EXEMPLARY NON-LIMITING EMBODIMENTS

[0022] Fig. 1A shows a block diagram of an embodiment of a signal amplifier device 1 according to the present invention. The signal amplifier device 1 is used to connect one or more mobile devices 2 to a base station 3. The signal amplifier device 1 is configured to receive a communication signal from the base station 3 and / or from the mobile device 2 and to retransmit this communication signal to the mobile device 2 and / or the base station 3. The signal amplifier device 1 is also capable of amplifying the respective communication signal.

[0023] During normal operation, the gain of the signal amplifier device 1 is preferably constant over a corresponding period of time, i.e., several seconds, minutes, or hours. The signal strength of the uplink signal received by the base station 3 is thus controlled by the mobile device 2, since the gain by the signal amplifier device 1 is more or less constant.

[0024] In another embodiment of the present invention, the signal amplifier device 1 is used within a means of transport, such as a vehicle, a train, a ship or an aircraft.

[0025] The signal amplifier device 1 comprises at least one first antenna 4a and at least one second antenna 4b. The at least one first antenna 4a is used to establish a communication connection between the signal amplifier device 1 and the mobile device 2. The at least one first antenna 4a is connected to an input port (not shown) of the signal amplifier device 1.

[0026] The at least one second antenna 4b is used to establish another communication connection between the signal amplifier device 1 and the base station 3. The at least one first antenna 4a is preferably arranged within the means of transport. This means that the at least one first antenna 4a is arranged within the vehicle, train, ship, or aircraft and is capable of covering the interior of the means of transport.

[0027] In contrast, the at least one second antenna 4b is preferably arranged outside the means of transport. The at least one second antenna 4b can be mounted, for example, but not limited to, on the roof of the vehicle, train, ship, or aircraft. With such an installation of the signal amplifier device 1, the mobile device 2 inside the means of transport can be easily connected to the base station 3. In this case, the mobile device 2 does not amplify its signals nearly to a maximum.

[0028] The at least one first antenna 4a and the mobile device 2 are further arranged close to one another. Preferably, the at least one first antenna 4a is mounted in a center console or dashboard of the vehicle. More preferably, the at least one first antenna 4a is mounted in a holder within the means of transport that is used to hold the mobile device 2. Thus, the attenuation between the mobile device 2 and the at least one first antenna 4a depends on the arrangement of the mobile device 2 with respect to the at least one first antenna 4a. A galvanic connection between the mobile device 2 and the at least one first antenna 4a would also be possible. This could be achieved, for example, using a coaxial cable.

[0029] In contrast, the at least one second antenna 4b can be arranged in an elevated position on the means of transport. This ensures that the communication connection between the at least one second antenna 4b and the base station 3 is secure. Even if the means of transport comprises an outer wall that is impermeable to electromagnetic radiation, the mobile device 2 can continue to communicate with the respective base station 3. Even if the signal transmitted via the at least one second antenna 4b is highly amplified, a user within the means of transport is not affected by the high-power radio frequency field.

[0030] It would also be possible to use a plurality of first antennas 4a and / or second antennas 4b. In this case, the signal amplifier device 1 could support MIMO (Multiple Input Multiple Output) operation.

[0031] The signal amplifier device 1 also provides a signal path 7 for electrically connecting the at least one first antenna 4a to the at least one second antenna 4b. As a result, the mobile device 2 can transmit an uplink signal to the base station 3 and can also receive a downlink signal from the base station 3.

[0032] The signal path 7 is therefore at least partially divided into a first downlink signal path 7a and a first uplink signal path 7b. The signal amplifier device 1 also includes at least one downlink amplifier 8a for amplifying a downlink signal and at least one uplink amplifier 8b for amplifying an uplink signal. Preferably, the at least one downlink amplifier 8a or both amplifiers 8a, 8b are low-noise amplifiers.

[0033] The at least one downlink amplifier 8a is arranged in the first downlink signal path 7a. The at least one uplink amplifier 8b is arranged in the first uplink signal path 7b. The signal amplifier device 1 also includes at least one first downlink power detector 9a for detecting a downlink signal power. The signal amplifier device 1 also includes a control unit 10 configured to receive a measured value from the at least one first downlink power detector 9a.

[0034] As can be seen, the signal amplifier device 1 also comprises a bypass line 13 for electrically connecting the at least one first antenna 4a directly to the at least one second antenna 4b.

[0035] According to the invention, the control unit 10 is designed to release (activate) the bypass line 13 when the measured value of the downlink signal power from the at least one first downlink power detector 9a exceeds a first limit value, so that the signal amplifier device 1 switches from the normal operating mode to the bypass mode. This means that in the bypass mode, the at least one downlink amplifier 8a and the at least one uplink amplifier 8b are electrically separated from the respective at least one first antenna 4a and at least one second antenna 4b. Both amplifiers can still be powered, but it is also possible for the power of both amplifiers 8a, 8b to be reduced or completely switched off.

[0036] It is particularly advantageous that the measured value of the downlink signal power, which indicates whether or not the noise exceeds a limit specified by the mobile communications industry standards, can be determined during testing of the signal amplifier device 1 (or a reference model), how high the noise level is in relation to the downlink signal power of a downlink signal at a donor port of the signal amplifier device 1. The donor port of the signal amplifier device 1 is the port to which the at least one second antenna 4b is connected.

[0037] Once the downlink signal power threshold is determined, the first limit value can be set to this threshold (i.e., during production) so that the bypass line 13 is activated after the first limit value is exceeded. As a result, uplink and downlink noise power exceeding -70 dBm / MHz is avoided. It is also avoided that both the uplink and downlink gain exceed 23 dB or the MSCL, whichever is smaller. The MSCL (Mobile Station Coupling Loss) is the minimum coupling loss in dB between the mobile device 2 and the input port of the signal amplifier device 1. The MSCL is calculated or measured for each operating frequency band. The MSCL also includes the path loss of the mobile device 2 and the antenna gain and cable loss of the signal amplifier device 1.

[0038] The signal amplifier device 1 also includes a first frequency division unit 5a and a second frequency division unit 5b. The first and second frequency division units 5a, 5b may be in the form of a duplexer 5a, 5b. They may also be referred to as a diplexer. Each of the first frequency division unit 5a and the second frequency division unit 5b has a first downlink port 6a, a first uplink port 6b, and a common connection port 6c.

[0039] The at least one first antenna 4a is electrically connected to the common connection port 6c of the first frequency division unit 5a via a first part 71 of the signal path 7. The at least one second antenna 4b is connected to the common connection port 6c of the second frequency division unit 5b via a second part 72 of the signal path 7. The first part 71 of the signal path 7 is split by the first frequency division unit 5a into the first downlink signal path 7a and the first uplink signal path 7b. The first downlink signal path 7a is connected to the first downlink port 6a of the first frequency division unit 5a, and the first uplink signal path 7b is connected to the first uplink port 6b of the first frequency division unit 5a.

[0040] The second part 72 of the signal path 7 is divided by the second frequency division unit 5b into a first downlink signal path 7a and a first uplink signal path 7b, wherein the first downlink signal path 7a is connected to the first downlink port 6a of the second frequency division unit 5b and wherein the first uplink signal path 7b is connected to the first uplink port 6b of the second frequency division unit 5b.

[0041] A first electrical downlink line 15a electrically connects the first downlink port 6a of the first frequency dividing unit 5a to the first downlink port 6a of the second frequency dividing unit 5b, thereby providing the first downlink signal path 7a.

[0042] A first electrical uplink line 15b electrically connects the first uplink port 6b of the first frequency dividing unit 5a to the first uplink port 6b of the second frequency dividing unit 5b, thereby providing the first uplink signal path 7b.

[0043] The at least one first downlink power detector 9a is placed in the first downlink path 7a or connected / coupled thereto.

[0044] When the signal amplifier device 1 is operated in bypass mode, the first and second frequency dividing units 5a, 5b are electrically separated from the respective at least one first and second antenna 4a, 4b.

[0045] To achieve this, the signal amplifier device 1 comprises a first circuit 12a and a second circuit 12b. Each of the first and second circuits 12a, 12b has a common connection port and at least one first and one second connection port. On the one hand, each of the first and second circuits 12a, 12b is configured to electrically connect the respective common connection port to the respective first connection port in a first switching state. On the other hand, each of the first and second circuits 12a, 12b is configured to electrically connect the respective common connection port to the respective second connection port in a second switching state.

[0046] The common connection port of the first circuit 12a is electrically connected to the at least one first antenna 4a and the common connection port of the second circuit 12b is electrically connected to the at least one second antenna 4b.

[0047] The first connection port of the first circuit 12a is electrically connected to the common connection port 6c of the first frequency dividing unit 5a and the first connection port of the second circuit 12b is electrically connected to the common connection port 6c of the second frequency dividing unit 5b.

[0048] The second connection port of the first circuit 12a is electrically connected to the second connection port of the second circuit 12b using the bypass line 13.

[0049] The control unit 10 is electrically connected to the first and second circuits 12a, 12b and is configured to control the first and second circuits 12a, 12b such that the first and second circuits 12a, 12b switch between the first switching state and the second switching state.

[0050] As stated above, the antennas 4a, 4b are directly connected to each other using the bypass line 13 when the downlink signal power exceeds the first threshold. For example, the first threshold is set to a value such that the bypass line 13 is activated (both circuits 12a, 12b switch to the second switching state) before the uplink and downlink noise power exceeds -70 dBm / MHz and before the uplink and downlink gain exceeds 23 dB or the MSCL (Mobile Station Coupling Loss), whichever is smaller.

[0051] Alternatively, if a test has demonstrated that the noise power of the signal amplifier device 1 only exceeds the limits specified by the mobile communications industry standards for high measured values of the downlink signal power (i.e., RSSI > -15 dBm), it could be the case that the bypass line 13 is activated when a gain between the first connection ports of the first and second circuits 12a, 12b is lower than a gain between the second connection ports of the first and second circuits 12a, 12b. For clarity, it should be noted that the amplification of the uplink signal and the downlink signal depends on the RSSI value. The RSSI (Received Signal Strength Indication) is the downlink portion of the received signal power in dBm with respect to the donor antenna port of the signal amplifier device 1 to which the at least one second antenna 4b is connected.The higher the RSSI value, the more the amplification of the uplink signal and the downlink signal must be reduced.

[0052] Reference is made to Fig. 4. There, it is shown that the uplink and downlink signal gain is +23 dB for an RSSI value between -60 dBm and -50 dBm. The +23 dB gain is permissible when using a mount to connect the mobile device 2 to the signal booster device 1. If the mobile device 2 is connected directly or if regular antennas are used instead of a mount, the value is different.

[0053] Starting with an RSSI value of -50 dBm, the gain is constantly reduced. This applies to both the uplink signal and the downlink signal. This can be achieved, for example, by reducing the supply voltage of the at least one downlink amplifier 8a and the at least one uplink amplifier 8b. As explained below, at least one attenuator 11 is preferably used to attenuate the gain of the uplink and downlink signals so that the gain can be kept constant (amplifiers are operated in a linear range).

[0054] With further reference to Fig. 4 that the gain of the downlink signal is lower than the gain of the bypass line 13 after the RSSI reaches a value of -24 dBm or more. This is the point at which the gain of a signal transmitted from the mobile device 2 to the base station 3 via the first and second frequency dividing units 5a, 5b and the uplink amplifier 8b would be more attenuated than a signal transmitted from the mobile device 2 to the base station 3 via the bypass line 13. In this case, it is preferable to control the first and second switching circuits 12a, 12b to switch from the first switching state to the second switching state, thereby activating the bypass line 13.

[0055] In the example in Fig. 4, the uplink signal gain drops from +7 dB to -40 dB when the RSSI reaches a value of -34 dBm. In this specific example, the uplink amplifier 8b is deactivated, providing a gain of -40 dB for the uplink signal. In this specific example, this is done because the uplink and downlink noise power exceed -70 dBm / MHz after the RSSI reaches -34 dBm. As a result, the prior art signal amplifier device would activate the transmit power-off mode, which is indicated by the low gain at approximately -40 dB.In contrast, the signal amplifier device 1 according to the present invention would activate only the bypass line 13, resulting in an uplink and downlink signal amplification of approximately -4 dB, which is significantly better than a -40 dB amplification by disabling the uplink amplifier 8b, as performed by the prior art amplifiers.

[0056] The formula for calculating the uplink signal gain and the downlink signal gain is: −34dB−RSSI+MSCL wherein the RSSI is the downlink portion of the received signal power in dBm at the donor port, and wherein the MSCL is the minimum coupling loss between the mobile device and an input port of the signal amplifier device to which the at least one first antenna is connected.

[0057] In the example in Fig. 4, the MSCL is set to 7 dB. The mobile communications industry standards explain in detail how the MSCL value is to be measured. Reference is made to Appendix B of Section 20.21.

[0058] After the signal amplifier device 1 switches from the normal operating mode to the bypass mode, the signal amplifier device 1 remains in the bypass mode as long as the measured value of the downlink signal power provided by the at least one first downlink power detector 9a remains above the first limit value. However, the control unit 10 is also configured to control the first and second switching circuits 12a, 12b such that the first and second switching circuits 12a, 12b switch from their second switching state (bypass mode) to the first switching state. This occurs when the measured value provided by the at least one first downlink power detector 9a falls below a second limit value. The second limit value can be as high as the first limit value, but is preferably below the first limit value, thereby preventing frequent switching around the first limit value (hysteresis).

[0059] The control unit 10 is also configured to control the first and second circuits 12a, 12b during the bypass mode such that the first and second circuits 12a, 12b regularly switch between the second switching state (bypass mode) and the first switching state. The control unit 10 is further configured to receive the measured value from the at least one first downlink power detector 9a in the first switching state. Reference is made to Fig. 5.

[0060] It should also be noted that the circuits 12a, 12b remain in the second switching state (after releasing the bypass mode) longer than in the first switching state (for obtaining measured values). Typically, the control unit 10 is configured to control the first and second circuits 12a, 12b during the bypass mode such that the first and second circuits 12a, 12b remain in the second switching state for more than 10 times, or 20 times, or 50 times, or 100 times, or 200 times, or 500 times, or 1000 times, or 2000 times, or 5000 times, or 7000 times, or 10000 times longer than in the first switching state.

[0061] The first switching state preferably lasts longer than 50 µs, 60 µs, 70 µs, 80 µs, 90 µs, 100 µs, 120 µs, 140 µs, 160 µs, 180 µs or 200 µs, but less than 500 µs, 400 µs, 300 µs, 200 µs or 150 µs.

[0062] As mentioned above, the signal amplifier device 1 also comprises at least one first attenuator 11. The at least one first attenuator 11 is preferably arranged between the first connection ports of the first and second circuits 12a, 12b. More specifically, the at least one first attenuator 11 is arranged between the first connection port of the first circuit 12a and the common connection port 6c of the first frequency division unit 5a. This is shown in Fig. 1A. It could also be possible for the at least one first attenuator 11 to be arranged between the first connection port of the second circuit 12b and the common connection port 6c of the second frequency division unit 5b. This is shown in Fig. 1B. It is also possible to use two attenuators 11, wherein one attenuator 11 is arranged between the first circuit 12a and the first frequency division unit 5a, and the second attenuator 11 is arranged between the second circuit 12b and the second frequency division unit 5b. This embodiment is shown in Fig. 1C.

[0063] The control unit 10 is electrically connected to the at least one first attenuator 11 and is configured to control the attenuation factor of the at least one first attenuator 11. The attenuation can preferably be changed stepwise or continuously.

[0064] In Fig. 1A to 1C, the at least one first attenuator 11 is arranged within the first part 71 of the signal path 7 and / or within the second part 72 of the signal path 7. Thus, the uplink and downlink signals are attenuated equally during normal operation.

[0065] The at least one first attenuator 11 is not only used to ensure that the uplink and downlink gain is maintained within the limits specified by the mobile communications industry standards (see the equation above), but it is also used during the bypass mode. As explained above, the control unit 10 is further configured to control the first and second switching circuits 12a, 12b during the bypass mode such that they regularly switch from the second switching state to the first switching state. The control unit 10 is also configured to control the at least one first attenuator 11 during the bypass mode such that the at least one first attenuator 11 is operated with at least 70%, 80%, or 90% of its maximum attenuation at least during the first switching state.As a result, it is ensured that the uplink signal is attenuated during the measurement so that the noise power remains within the standards of the mobile communications industry.

[0066] It is also possible that the attenuation of the at least one first attenuator 11 remains increased throughout the entire duration of the bypass mode.

[0067] Instead of periodically switching between the second switching state and the first switching state in bypass mode, it would also be possible for the signal amplifier device 1 to comprise a second downlink power detector 9c for detecting a downlink signal power in the bypass line 13. The control unit 10 is then configured to receive a measured value from the second downlink power detector 9c, wherein the control unit 10 is also configured to control the first and second circuits 12a, 12b during the bypass mode with respect to the measured value obtained from the second downlink power detector 9c. To do this, a filter network should preferably be used so that only the downlink signals are fed into or coupled to the second downlink power detector 9c. Such an embodiment is described, for example, in Fig. 1D shown.

[0068] It should also be noted that each of the at least one downlink and uplink amplifier 8a, 8b is configured to operate with a constant gain. Thus, the control unit 10 is configured to control the attenuation factor of the at least one first attenuator 11 to keep the output of the signal amplifier device 1 at the at least one second antenna 4b within the limits required by the mobile communications industry standards.

[0069] Fig. 1A to 1D also show that the signal amplifier device 1 comprises at least one first uplink power detector 9b for detecting an uplink signal power. The at least one first uplink power detector 9b is arranged in the first uplink path 7b, and the control unit 10 is configured to receive a measured value from the at least one first uplink power detector 9b.

[0070] The following refers to Fig. 1D. As can be seen, the downlink signal path 7a is surrounded by a dotted rectangle. In contrast, the uplink signal path 7b is surrounded by a dashed rectangle.

[0071] Now Fig. 2A and Fig. 2B is referred to. Fig. Figure 2A shows an exemplary embodiment of the uplink signal path 7b, wherein Fig. 2B shows an exemplary embodiment of the downlink signal path 7a. It is also apparent that the signal amplifier device 1 is configured to transmit different signals corresponding to at least two different mobile radio bands (i.e., the communication bands should be: 2, 4, 5, 12, 13, and / or 17). This means that the signal amplifier device 1 is configured to transmit two different communication signals consecutively belonging to two different communication bands (i.e., the mobile device 2 switches the communication band during a call (GSM to UMPTS)). It might also be possible for the signal amplifier device 1 to transmit two communication signals simultaneously belonging to two different communication bands. This might be possible, for example, when two mobile devices 2 are used at the same time.

[0072] Fig. 2A and Fig. 2B show that the communication signals belonging to different communication bands can be amplified independently of each other.

[0073] To enable this, the signal amplifier device 1 further comprises a first and a second uplink adaptation network 20a, 20b arranged within the first uplink signal path 7b. The first uplink adaptation network 20a is connected to the first frequency division unit 5a and is configured to divide the first uplink signal path 7b into at least two uplink branches 21a, 21b, wherein the first uplink adaptation network 20a is further configured to forward each of the at least two mobile radio bands into a different branch 21a, 21b.

[0074] The second uplink adaptation network 20b is connected to the second frequency division unit 5b and is designed to combine the at least two uplink branches 21a, 21b to form the first uplink signal path 7b.

[0075] The first and second matching networks 20a, 20b may comprise a filter network. They may also be referred to as diplexers.

[0076] The signal amplifier device 1 further comprises at least one other uplink amplifier 22a, 22b, which is arranged in each of the at least two uplink branches 21a, 21b and is configured to amplify the communication signal of the respective communication band transmitted via the respective uplink branch 21a, 21b. The at least one other uplink amplifier 22a, 22b can be configured to amplify the communication signals of the respective communication bands differently. This means that one communication band is amplified more than the other communication band. The different amplification is preferably used to compensate for different losses due to different frequencies.

[0077] It is also shown that the at least one uplink power detector 9b can be arranged at different positions (dotted-dashed line). It is also possible for the signal amplifier device 1 to comprise at least one other uplink power detector 23, which is preferably arranged in each of the at least two uplink branches 21a, 21b before and / or after the respective at least one other uplink amplifier 22a, 22b. The control unit 10 is further configured to receive a measured value from the at least one other uplink power detector 23 in each of the at least two uplink branches 21a, 21b.

[0078] As from Fig. As can be seen in Figure 2A, the at least one uplink amplifier 8b is arranged in the uplink signal path 7b and is designed to amplify all communication signals transmitted via the uplink signal path 7b. Accordingly, the at least one uplink amplifier 8b is capable of amplifying communication signals on different communication bands. In contrast, the at least one other uplink amplifier 22a, 22b arranged in different uplink branches 21a, 21b only amplifies communication signals of the respective communication band.

[0079] With reference to Fig. 2B, the same structure is shown for the downlink signal path 7a. The signal amplifier device 1 is also configured to receive signals corresponding to at least two different mobile radio bands on the first downlink signal path 7a. The signal amplifier device 1 comprises a first and a second downlink matching network 25a, 25b arranged within the first downlink signal path 7a.

[0080] The second downlink adaptation network 25b is connected to the second frequency division unit 5b and is configured to divide the first downlink signal path 7a into at least two downlink branches 26a, 26b, wherein the second downlink adaptation network 25b is further configured to forward each of the at least two mobile radio bands into a different downlink branch 26a, 26b.

[0081] The first downlink adaptation network 25a is connected to the first frequency division unit 5a or to the at least one downlink amplifier 8a (as shown in Fig. 2B). The first downlink adaptation network 25a is configured to combine the at least two downlink branches 26a, 26b back to the first downlink signal path 7a.

[0082] At least one other downlink amplifier 27a, 27b is arranged in each of the at least two downlink branches 26a, 26b and is designed to amplify the communication signal of the respective communication band transmitted via the respective downlink branch 26a, 26b.

[0083] It can also be seen that the at least one other downlink power detector 28 is arranged in each of the at least two downlink branches 26a, 26b before and / or after the respective at least one other downlink amplifier 27a, 27b. The control unit 10 is also configured to receive a measured value from the at least one other downlink power detector 28 in each of the at least two downlink branches 26a, 26b.

[0084] The at least one downlink amplifier 8a is designed to amplify downlink signals of different communication bands, wherein the at least one other downlink amplifier 27a, 27b is designed to amplify a communication signal of a respective communication band, but not all communication bands for which the signal amplifier device 1 is used.

[0085] Reference is now made to Fig. 3A, Fig. 3B and Fig. 3C. These figures show a signal amplifier device 1, wherein the first part 71 of the signal path 7 is further divided into a second downlink signal path 7c ( Fig. 3B, Fig. 3C) and a second uplink signal path 7d ( Fig. 3A). This is performed by the first frequency division unit 5a. The second downlink signal path 7c is connected to the second downlink port of the first frequency division unit 5a. The second uplink signal path 7d is connected to the second uplink port of the first frequency division unit 5a.

[0086] The second part 72 of the signal path 7 is also divided by the second frequency division unit 5b into a second downlink signal path 7c ( Fig. 3B, Fig. 3C) and a second uplink signal path 7d ( Fig. 3A). The second downlink signal path 7c is connected to the second downlink port of the second frequency division unit 5b, and the second uplink signal path 7d is connected to the second uplink port of the second frequency division unit 5b.

[0087] The first uplink path and the first downlink path 7a, 7b are used for transmitting and / or receiving in a low-frequency band comprising various mobile radio bands. The low-frequency band preferably comprises mobile radio bands below 1000 MHz, below 1200 MHz, or below 1400 MHz.

[0088] The second downlink path and the second uplink path 7c, 7d are used for transmitting and / or receiving in a high-frequency band comprising various mobile radio bands. The high-frequency band preferably comprises mobile radio bands above 1000 MHz, above 1200 MHz, or above 1400 MHz.

[0089] The low-frequency band preferably includes mobile radio bands 5, 12, 13, and 17, and the high-frequency band includes mobile radio bands 2 and 4. Please note that the aforementioned mobile radio bands are used in the United States. Other countries permit or require the use of other mobile radio bands.

[0090] As from Fig. 3A, the first uplink signal path 7b and the second uplink signal path 7d comprise the same structure as in Fig. 2A. Reference is made to this.

[0091] Concerning the first and second downlink signal paths 7a, 7c in Fig. 3B, these include the same structure as in Fig. 2B. However, the at least one downlink amplifier 8a is drawn with a dashed line, indicating that the at least one downlink amplifier 8a is optional.

[0092] Reference is now made to Fig. 3C. It can be seen that the first and second downlink signal paths 7a, 7c comprise a common amplifier 8a. The first matching network 25a is designed to combine the two downlink branches 26a, 26b of the first and second downlink signal paths 7a, 7c into a single electrical line 31. The common amplifier 8a is arranged within the single electrical line 31. The at least one first power detector 9a is arranged before and / or after the common amplifier 8a. A further matching network 32 for dividing the single line 31 into the first downlink signal path 7a and the second downlink signal path 7c is arranged between the common amplifier 8a and the first frequency division unit 5a. The common amplifier 8a can also be the at least one downlink amplifier 8a.

[0093] The first and second frequency division units 5a, 5b may comprise a first frequency divider (i.e., a filter network) configured to separate the high-frequency band from the low-frequency band. Subsequently, multiple duplexers may be used to separate the uplink signal paths 7b, 7d from the downlink signal paths 7a, 7c and from each other in the respective low-frequency / high-frequency bands.

[0094] The first and second circuits 12a, 12b are preferably SPDT semiconductor elements (Single Pole Double Throw).

[0095] The at least one downlink amplifier 8a and / or the at least one uplink amplifier 8b are preferably low-noise amplifiers (LNA).

[0096] The signal transmitted and amplified by the signal amplifier device 1 is a 2G, 3G, 4G and / or 5G signal.

[0097] Examples of 2G signals include GSM, GPRS, EDGE and EDGE+.

[0098] Examples of 3G signals include UMTS, HSPA, HSPA+ and W-CDMA.

[0099] 4G signals include LTE and LTE-Advanced.

[0100] 5G signals are also supported by the signal booster device because they use similar frequencies and power levels.

[0101] The first and / or second frequency division unit 5a, 5b could comprise a waveguide filter structure.

[0102] The at least one downlink amplifier 8a and the at least one uplink amplifier 8b may comprise more than one amplifier or amplifier stage. For example, it is possible for the at least one downlink amplifier 8a and the at least one uplink amplifier 8b to comprise a preamplifier and a main amplifier.

[0103] Reference is now made to Fig. 6, which shows a flowchart explaining the method of operating the signal amplifier device 1.

[0104] In a first step S1, a measured value is obtained from the at least one first downlink power detector 9a. It is obvious that this measured value can also be an already averaged value from a plurality of successively obtained measured values.

[0105] In a second step S2, it is determined whether the measured value of the at least one first downlink power detector 9a exceeds a first limit value.

[0106] In step S3, the signal amplifier device 1 is switched from the normal operating mode to the bypass mode if the measured value of the at least one first downlink power detector 9a exceeds the first limit value, thereby electrically isolating the at least one downlink amplifier 8a and the at least one uplink amplifier 8b from the respective at least one first antenna 4a and the respective at least one second antenna 4b. If this is not the case, the signal amplifier device 1 continues to operate in the normal operating mode.

[0107] The first and / or second frequency division units 5a, 5b may comprise separate elements (i.e., duplexers) connected to each other by electrical lines. For clarity, the first and second frequency division units 5a, 5b are represented by only one block. However, the design should encompass both variants: a compact first and second frequency division unit 5a, 5b, each comprising only one frequency division element, and a first and second frequency division unit 5a, 5b comprising multiple interconnected frequency division elements.

[0108] It should be noted that the at least one first attenuator 11, the first and second frequency dividing units 5a, 5b, the at least one downlink amplifier 8a and the at least one uplink amplifier 8b are arranged between the first connection ports of the first and second circuits 12a, 12b.

[0109] It should also be noted that a filter (ie, a low-pass filter, a high-pass filter, a band-pass filter) can be arranged after each amplifier 8a, 8b. This also applies to the various matching networks 20a, 20b, 25a, 25b, 32 used in the signal amplifier device 1.

[0110] Furthermore, the bypass line 13 preferably does not contain any amplifying elements and / or attenuators and / or filter networks.

[0111] The invention is not limited to the described embodiments. Within the scope of the invention, all described and / or suggested features may be combined with one another in any desired manner.

Claims

[1] Signal amplifier device for amplifying signals in a wireless communication network, wherein the signal amplifier device comprises at least a first antenna for communicating with a mobile device and at least a second antenna for communicating with a base station, wherein the signal amplifier device provides a signal path for electrically connecting the at least one first antenna to the at least one second antenna for transmitting uplink and downlink signals, wherein the signal path is at least partially divided into a first downlink signal path and a first uplink signal path, wherein the signal amplifier device comprises at least one downlink amplifier for amplifying a downlink signal and at least one uplink amplifier for amplifying an uplink signal, wherein the at least one downlink amplifier is arranged in the first downlink signal path and wherein the at least one uplink amplifier is arranged in the first uplink signal path, wherein the signal amplifier device comprises at least a first downlink power detector for detecting a downlink signal power, wherein the signal amplifier device comprises a bypass line for directly electrically connecting the at least one first antenna to the at least one second antenna, wherein the signal amplifier device also comprises a control unit configured to obtain a measured value from the at least one first downlink power detector, wherein the control unit is further configured to activate the bypass line when the measured value of the downlink signal power from the at least one first downlink power detector exceeds a first limit value, so that the signal amplifier device switches from the normal operating mode to the bypass mode, wherein the at least one downlink amplifier and the at least one uplink amplifier are electrically isolated from the respective at least one first antenna and at least one second antenna when the bypass line is activated. [2] The signal amplifier device according to claim 1, wherein the signal amplifier device comprises a first frequency dividing unit and a second frequency dividing unit, each of the first frequency dividing unit and the second frequency dividing unit having a first downlink port, a first uplink port and a common connection port, wherein the at least one first antenna is electrically connected to the common connection port of the first frequency division unit via a first part of the signal path, wherein the at least one second antenna is electrically connected to the common connection port of the second frequency division unit via a second part of the signal path, wherein the first part of the signal path is divided by the first frequency division unit into a first downlink signal path and a first uplink signal path, wherein the first downlink signal path is connected to the first downlink port of the first frequency division unit and wherein the first uplink signal path is connected to the first uplink port of the first frequency division unit; wherein the second part of the signal path is divided by the second frequency division unit into a first downlink signal path and a first uplink signal path, wherein the first downlink signal path is connected to the first downlink port of the second frequency division unit and wherein the first uplink signal path is connected to the first uplink port of the second frequency division unit; wherein a first electrical downlink line electrically connects the first downlink port of the first frequency division unit to the first downlink port of the second frequency division unit, thereby providing the first downlink signal path, wherein a first electrical uplink line electrically connects the first uplink port of the first frequency division unit to the first uplink port of the second frequency division unit, thereby providing the first uplink signal path, wherein the at least one first downlink power detector is arranged in the first downlink path, wherein the first and second frequency dividing units are separated from the respective at least one first and second antenna when the bypass line is activated. [3] A signal amplifier device according to claim 2, wherein the signal amplifier device comprises a first circuit and a second circuit, wherein each of the first and second circuits has a common connection port and at least a first and a second connection port, wherein each of the first and second circuits is configured to electrically connect the respective common connection port to the respective first connection port in a first switching state, and wherein each of the first and second circuits is configured to electrically connect the respective common connection port to the respective second connection port in a second switching state, wherein the common connection port of the first circuit is electrically connected to the at least one first antenna and wherein the common connection port of the second circuit is electrically connected to the at least one second antenna, wherein the first connection port of the first circuit is electrically connected to the common connection port of the first frequency dividing unit, and wherein the first connection port of the second circuit is electrically connected to the common connection port of the second frequency dividing unit, wherein the second connection port of the first circuit is electrically connected to the second connection port of the second circuit, thereby forming the bypass line, wherein the control unit is electrically connected to the first and second circuits and is configured to control the first and second circuits such that the first and second circuits switch to the respective first switching state or the respective second switching state. [4] A signal amplifier device according to claim 3, wherein the first limit value is set to such a value that the bypass line is activated: a) before the uplink and downlink noise power exceed -70 dBm / MHz and before the uplink gain exceeds 23 dB or the MSCL (Mobile Station Coupling Loss), whichever is smaller, where the MSCL is the minimum coupling loss between the mobile device and an input port of the signal amplifier device to which the at least one first antenna is connected; and / or b) if an amplification of a signal between the first connection ports of the first and second circuits is less than an amplification of a signal between the second connection ports of the first and second circuits. [5] The signal amplifier device according to claim 3, wherein the control unit is configured to control the first and second circuits such that the first and second circuits switch to their respective first switching states when the measured value of the at least one first downlink power detector falls below a second threshold value, so that the signal amplifier device can be operated in a normal operating mode. [6] Signal amplifier device according to claim 5, wherein the second limit value a) is equal to the first limit; or b) is smaller than the first limit. [7] The signal amplifier device according to claim 5, wherein the control unit is configured to control the first and second circuits during the bypass mode such that the first and second circuits regularly switch between the second switching state and the first switching state, wherein the control unit is further configured to receive the measured value from the at least one first downlink power detector in the first switching state. [8] The signal amplifier device according to claim 7, wherein the control unit is configured to control the first and second circuits during the bypass mode such that the first and second circuits remain in the second switching state for more than 10 times or 20 times or 50 times or 100 times or 200 times or 500 times or 1000 times or 2000 times or 5000 times or 7000 times or 10000 times longer than in the first switching state. [9] Signal amplifier device according to claim 8, wherein the first switching state preferably lasts longer than 50 µs, 60 µs, 70 µs, 80 µs, 90 µs, 100 µs, 120 µs, 140 µs, 160 µs, 180 µs or 200 µs, but less than 500 µs, 400 µs, 300 µs, 200 µs or 150 µs. [10] Signal amplifier device according to claim 3, wherein the signal amplifier device comprises at least a first attenuator, wherein the at least one first attenuator is arranged between the first connection ports of the first and second circuits, wherein the control unit is designed to control the damping factor of the at least one first attenuator. [11] A signal amplifier device according to claim 10, wherein the at least one first attenuator is arranged between the first connection port of the first circuit and the common connection port of the first frequency dividing unit and / or wherein the at least one first attenuator is arranged between the first connection port of the second circuit and the common connection port of the second frequency dividing unit. [12] Signal amplifier device according to claim 7 and claim 10, wherein the control unit is further configured to control the at least one first attenuator during the bypass mode such that the at least one first attenuator is operated with at least 70% or 80% or 90% of its maximum attenuation at least during the first switching state. [13] A signal amplifier device according to claim 10, wherein each of the at least one downlink and uplink amplifier is configured to operate at a constant gain, wherein the control unit is configured to control the attenuation factor of the at least one first attenuator to keep the output of the signal amplifier device at the at least one second antenna within the limits required by the mobile radio industry standards. [14] The signal amplifier device according to claim 13, wherein the control unit is configured to control the attenuation factor of the at least one first attenuator such that an uplink gain at a donor port to which the at least one second antenna is connected does not exceed -34dB-RSSI + MSCL, where the RSSI is the downlink portion of the received signal power in dBm at the donor port and wherein the MSCL is the minimum coupling loss between the mobile device and an input port of the signal amplifier device to which the at least one first antenna is connected. [15] The signal amplifier device according to claim 5, wherein the signal amplifier device comprises a second downlink power detector for detecting a downlink signal power in the bypass line, wherein the control unit is configured to obtain a measured value from the second downlink power detector, wherein the control unit is configured to control the first and second circuits during the bypass mode with respect to the measured value obtained from the second downlink power detector. [16] A signal amplifier device according to claim 3, wherein the first and second circuits are SPDT (Single Pole Double Throw) semiconductor elements. [17] The signal amplifier device according to claim 1, wherein the at least one downlink amplifier and / or the at least one uplink amplifier are low noise amplifiers (LNA). [18] The signal amplifier device according to claim 1, wherein the signal is a 2G, 3G, 4G and / or 5G signal. [19] Signal amplifier device according to claim 2, wherein the at least one first downlink power detector is arranged in the first downlink path between the first frequency division unit and the at least one downlink amplifier and / or wherein the at least one first downlink power detector is arranged in the first downlink path between the second frequency division unit and the at least one downlink amplifier and / or wherein the signal amplifier device comprises at least one first uplink power detector for detecting an uplink signal power, wherein the at least one first uplink power detector is arranged in the first uplink path, and wherein the control unit is configured to obtain a measured value from the at least one first uplink power detector. [20] The signal amplifier device according to claim 2, wherein the signal amplifier device is configured to transmit different signals corresponding to at least two different mobile radio bands via the first uplink signal path between the first and second frequency dividing units, wherein the signal amplifier device further comprises a first and a second uplink matching network arranged within the first uplink signal path, wherein the first uplink adaptation network is connected to the first frequency division unit and is configured to divide the first uplink signal path into at least two uplink branches, wherein the first uplink adaptation network is further configured to forward each of the two mobile radio bands into a different branch, wherein the second uplink adaptation network is connected to the second frequency division unit and is designed to combine the at least two uplink branches to form the first uplink signal path, wherein at least one other uplink amplifier is arranged in each of the at least two uplink branches and is configured to amplify the communication signal of the respective communication band transmitted via the respective uplink branch. [21] A signal amplifier device according to claim 20, wherein at least one other uplink power detector is arranged in each of the at least two uplink branches before and / or after the respective at least one other uplink amplifier, wherein the control unit is adapted to obtain a measured value from the at least one other uplink power detector in each of the at least two uplink branches. [22] The signal amplifier device according to claim 2, wherein the first part of the signal path from the first frequency dividing unit is also divided into a second downlink signal path and a second uplink signal path, the second downlink signal path being connected to the second downlink port of the first frequency dividing unit and the second uplink signal path being connected to the second uplink port of the first frequency dividing unit; wherein the second part of the signal path is divided by the second frequency division unit into a second downlink signal path and a second uplink signal path, wherein the second downlink signal path is connected to the second downlink port of the second frequency division unit and wherein the second uplink signal path is connected to the second uplink port of the second frequency division unit; wherein the first uplink path and the first downlink path are used for transmitting in a low frequency band comprising different mobile radio bands, wherein the second uplink path and the second downlink path are used for transmitting in a radio frequency band comprising different mobile radio bands. [23] Signal amplifier device according to claim 22, wherein the low frequency band comprises mobile radio bands below 1000 MHz or below 1200 MHz or below 1400 MHz and wherein the high frequency band comprises mobile radio bands above 1000 MHz or above 1200 MHz or above 1400 MHz and / or wherein the low frequency band comprises the mobile radio bands 5, 12, 13, 17 and the high frequency band comprises the mobile radio bands 2, 4. [24] The signal amplifier device of claim 22, wherein the first downlink signal path and the second downlink signal path are partially merged into a single electrical line, wherein the at least one downlink amplifier is arranged within the single electrical line. [25] Signal amplifier device according to claim 2, wherein the signal amplifier device is configured to receive signals corresponding to at least two different mobile radio bands on the first downlink signal path, wherein the signal amplifier device further comprises a first and a second downlink matching network arranged within the first downlink signal path, wherein the second downlink adaptation network is connected to the second frequency division unit and is designed to divide the first downlink signal path into at least two downlink branches, wherein the second downlink adaptation network is further designed to forward each of the at least two mobile radio bands into a different branch, wherein the first downlink adaptation network is connected to the first frequency division unit or the at least one downlink amplifier, and wherein the first downlink adaptation network is configured to combine the at least two downlink branches back to the first downlink signal path, wherein at least one other downlink amplifier is arranged in each of the at least two downlink branches and is configured to amplify the communication signal of the respective communication band transmitted via the respective downlink branch. [26] A signal amplifier device according to claim 25, wherein at least one other downlink power detector is arranged in each of the at least two downlink branches before and / or after the respective at least one other downlink amplifier, wherein the control unit is adapted to obtain a measured value from the at least one other downlink power detector in each of the at least two downlink branches. [27] The means of transport, in particular a vehicle, a ship, a train or an aircraft, wherein the means of transport comprises a signal amplifier device according to claim 1, wherein the at least one first antenna is arranged inside the means of transport and wherein the at least one second antenna is arranged on the outside of the means of transport. [28] Method for amplifying signals in a signal amplifier device, wherein the signal amplifier device comprises at least a first antenna for communicating with a mobile device and at least a second antenna for communicating with a base station, wherein the signal amplifier device provides a signal path for electrically connecting the at least one first antenna to the at least one second antenna for transmitting uplink and downlink signals, wherein the signal amplifier device comprises at least one downlink amplifier for amplifying a downlink signal and at least one uplink amplifier for amplifying an uplink signal, wherein the signal amplifier device comprises at least a first downlink power detector for detecting a downlink signal power, wherein the signal amplifier device comprises a bypass line for directly electrically connecting the at least one first antenna to the at least one second antenna, wherein the signal amplifier device also comprises a control unit configured to receive a measured value from the at least one first downlink power detector, wherein the control unit is further configured to activate the bypass line, the method comprising the following steps for amplifying signals in a signal amplifier device: Obtaining a measured value from the at least one first downlink power detector, Determining whether the measured value of the at least one first downlink power detector exceeds a first limit value, Switching from the normal operating mode to the bypass mode when the measured value of the at least one first downlink power detector exceeds the first limit value, whereby the at least one downlink amplifier and the at least one uplink amplifier are electrically isolated from the at least one first antenna and the at least one second antenna, respectively.

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