Self-powered amplifier device for a transceiver antenna

Abstract

The self-powered amplifier device (100) for transceiver antenna comprises: - a low-noise RF amplifier (2), capable of amplifying an RF signal injected into its own input (IN) and making it available at its own output (OUT); - a first electronic switch (3), electrically connected to a radiating assembly (101 ), to the input (IN) of the RF amplifier (2) and to a bypass signal line (LB); - a second electronic switch (4), electrically connected to an input / output terminal (102) by means of a signal line (104), to the output (OUT) of the RF amplifier (2) and to the bypass signal line (LB); - power supply means (5) of the first (3) and second (4) electronic switches, comprising an RF / DC converter (51 ) connected to the signal line (104), suitable for taking from the same a part of the RF power signal during the transmitting phases and converting it into direct current, and also connected to the first (3) and second (4) electronic switches to supply them with electrical power during the aforementioned transmitting phases.

Description

[0001] SELF-POWERED AMPLIFIER DEVICE FOR TRANSCEIVER

[0002] ANTENNA

[0003] TECHNICAL FIELD

[0004] The present invention falls within the technical sector relating to radio frequency telecommunications.

[0005] More particularly, the invention relates to a self-powered radio frequency low noise amplifier (LNA) device for transceiver antennas.

[0006] BACKGROUND ART

[0007] Civilian and military radiocommunications systems use antennas, including portable ones, for voice and data connections with other terrestrial or satellite stations. The radio link between two stations is more stable and reliable the higher the intensity of the signals arriving at the receiver's input, sufficiently rising above the background noise produced primarily by the receiver's electronics.

[0008] TECHNICAL PROBLEM

[0009] If the signal level received by the antenna and, subsequently, by a radio station's receiver is very low, or even close to the receiver's sensitivity threshold, the connection becomes vulnerable. In these cases, the useful signal may be detected intermittently, resulting in communication being disturbed to the point of being incomprehensible. Or, especially in the case of digital communications, the signal may be detected with errors in the received data, forcing the continuous retransmission of data packets and thus significantly reducing the connection's efficiency. The consequences of this problem can be potentially serious, especially in cases where radio communications are essential for the operator's safety or the success of an operation. This is the case, for example, in the military field, with communications occurring between mobile stations installed on vehicles or used by the military, or between mobile stations and satellites, where the stability and reliability of transmissions in any situation are of the utmost importance.

[0010] Secure connections are guaranteed not only by the performance of the transceiver equipment, but also by the features of the antennas used. Antenna size is typically associated with its receiving and transmitting capacity (gain), but in all cases where communications occur on the move, for example with stations installed on land, sea, or air vehicles or via portable individual transceivers, antennas must be relatively small and generally cannot have directivity gain, as they are necessarily designed for use in conditions where it is not possible to point the correspondent, regardless of whether it is a terrestrial or satellite station. In these cases, it is advisable to increase the receiving gain using a low- noise amplifier (LNA), placed between the antenna and the radio. This amplifier has the sole purpose of amplifying the received signal before it is applied to the receiver's input stage, thus improving the signal-to-noise ratio and resulting in a better receiving margin.

[0011] In some cases, the aforementioned LNA is inserted inside the receiving antenna itself, thus avoiding the presence of an additional external device and thus minimizing the attenuation loss in the transmission line section between the antenna and the LNA input. This attenuation would partially nullify the low-noise amplification effect of the LNA itself. Since the LNA is a unidirectional device that amplifies the very weak signal coming from the antenna and directed to the receiver, it must be excluded when the transceiver radio is put into transmission mode, to avoid damage to it by the high-power signal emitted by the radio and traveling to the antenna, which in this case is used for transmission.

[0012] In currently adopted solutions, LNA bypass — that is, the creation of a path for the RF signal to pass outside the LNA without entering it through its output port — is achieved with electromechanical relays that, during receiving, are powered by a current supplied by the radio itself through the antenna connector and applied to the LNA via the RF cable and an extractor circuit. During this phase, the same current is also applied to the amplifier chip, which represents the active part of the LNA. During transmission, the radio stops supplying DC current through the RF antenna connector; consequently, the relays remain de-energized and return to their rest position, creating the LNA's RF bypass path.

[0013] This solution, which currently represents the state of the art in portable antennas equipped with LNA amplifiers, has several disadvantages: a) the switching time from RX to TX and vice versa depends essentially on the mechanical switching time of the relays, which on average causes a delay of 2 milliseconds in the transition between the two states; this delay could, in the case of digital communications, lead to packet loss; b) since in the case of digital communications, continuous switching between RX and TX is required to send the "acknowledgements" required by the communication protocols, even if the switching speed of the electromechanical relays allows for correct operation of the connection, the relays are subjected to continuous switching, with annoying "buzzing" noise, which in the case of operations in critical conditions can be dangerous as it is easily detectable; c) the continuous switching of the relays, in addition to causing the aforementioned noise, leads to a rapid deterioration of the quality of the contacts which, especially in cases where the switching occurs when a power RF signal is already present, oxidize and become unreliable.

[0014] To solve the entire series of problems described, it is necessary to use switching devices to bypass the LNA during transmission. These devices are not electromechanical, but rather electronic, which are much faster. These devices are commonly available on the market and widely used in RF signal switching, but they present an insurmountable problem when used with transceiver radios that provide power only in the receiving state. These devices, in fact, require power at all times, regardless of whether the radio is in the receiving or transmitting state, requiring one or the other of the ports through which they route the receiving and transmitting signal to be kept conductive.

[0015] Therefore, if the power supply were to fail while the radio was transmitting, the power supplied by the radio itself would not be able to flow normally through the bypass path outside the LNA, as this is not set up. Furthermore, the electronic switching devices would be placed in an undefined state, in which the behaviour of the RF power signal would be unpredictable, which would most likely permanently damage either the switching device itself or the LNA.

[0016] OBJECTS OF THE INVENTION

[0017] The object of this invention is to provide a self-powered, low-noise radio frequency antenna amplifier device, which can be used in particular in conjunction with radio equipment designed to supply direct current power to the antenna only during RF signal reception. To this end, the amplifier device is equipped with means for powering the electronic switching devices that bypass the LNA during transmission of the antenna, without requiring external power sources to the antenna itself.

[0018] Another object of the invention is to provide a low-noise radio frequency amplifier device equipped with means for maintaining the aforementioned power supply of the electronic switching devices even in situations of transition between the receiving and transmitting states and vice versa.

[0019] A further object of the invention is to provide a circuit configuration for the radio frequency signal from the radio equipment to the antenna, and from the antenna to the radio equipment through the aforementioned LNA, capable of ensuring the power supply of the electronic switching devices even during the receiving phase. SUMMARY OF THE INVENTION

[0020] These and other purposes are fully achieved by a self-powered amplifier device for transceiver antenna, which comprises:

[0021] - a low-noise RF amplifier, capable of amplifying an RF signal injected into its input and making it available at its output;

[0022] - a first electronic switch, electrically connected to a radiating assembly, to the RF amplifier input and to a bypass signal line;

[0023] - a second electronic switch, electrically connected to an input / output terminal by means of a signal line, to the output of the RF amplifier and to the bypass signal line;

[0024] - power supply means for the first and second electronic switches, comprising an RF / DC converter connected to the signal line, capable of taking from it a portion of the RF power signal during the transmitting phases and converting it into direct current, and also connected to the first and second electronic switches to supply them with electrical power during the aforementioned transmitting phases.

[0025] BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The features of the invention will become apparent from the following description of preferred embodiments of a self-powered antenna amplifier (LNA) device, in accordance with the content of main claim No. 1 and with the aid of the attached drawing tables, in which:

[0027] - Figure 1 schematically shows a portable transceiver antenna, equipped with a self-powered LNA device made according to the invention;

[0028] - Figure 2 shows a block diagram of the self-powered LNA device of Figure 1 , made according to a preferred embodiment of the invention, in which the paths of the RF signal and the power lines of the electronic switches are highlighted with the antenna in the receiving phase;

[0029] - Figure 3 illustrates the block diagram of Figure 1 in which the paths of the RF signal and the power lines of the electronic switches are highlighted with the antenna in the transmitting phase;

[0030] - Figure 4 illustrates the block diagram of Figure 1 , in which the paths of the RF signal and the power lines of the electronic switches are highlighted in solid lines with the antenna in the transition phase between receiving and transmitting.

[0031] DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

[0032] With reference to figure 1 , and to a preferred embodiment of the invention, 100 indicates a portable transceiver antenna, usable for satellite or terrestrial radio communications, which incorporates a self- powered amplifier device 1 which is the object of the invention.

[0033] In particular, the antenna 100 comprises a body 100a, suitable for supporting the functional components of the antenna 100 itself, and for simultaneously acting as a handle to allow its use in the field by a person who needs to carry out radio communications, for example a soldier during an operational action. It should be understood that both the type of antenna 100 illustrated and its methods of use are described and illustrated purely by way of example. The self-powered amplifier device 1 object of the invention, in fact, can be advantageously installed on any transceiver antenna in which the presence of a low-noise amplifier for the received signal is foreseen.

[0034] In more detail, the antenna 100 comprises a radiating assembly 101 , supported at one end of the body 100a, which in the example illustrated is of the crossed dipole type.

[0035] The self-powered amplifier device 1 is electrically connected to the radiating group 101 , in practice made on a printed circuit board installed inside the same body 100a, which is also connected, by means of a signal line 104, to an input / output terminal 102. The latter is fixed to the opposite end of the body 100a with respect to the radiating group 101 , and is intended to allow connection to a radio device 103, in transmission and receive, via a connection line 105.

[0036] The radio equipment 103 is of a known type, and provides for making a direct current power supply source available on the connection line 105, only during the receiving phases.

[0037] Figure 2 shows the amplifier device 1 in a radio frequency (RF) signal receiving phase, in which the radiating group 101 is excited by an electromagnetic field and produces a low-power RF signal, intended to be amplified before being forwarded to the radio equipment 103 through the input / output terminal 102 and the connection line 105.

[0038] In this regard, the amplifying device 1 comprises a low-noise RF amplifier (LNA - Low Noise Amplifier) 2, a first electronic switching device 3, and a second electronic switching device 4, the latter intended to insert the LNA 2 into a circuit between the radiating group 101 and the input / output terminal 102 during the receiving phases, and to exclude it during the transmitting phases. All the devices listed above are essentially of a known type, and will therefore not be described in further detail.

[0039] In particular, during the receiving phases, an input IN of the LNA 2 is electrically connected to the radiating group 101 with the interposition of the first switch 3; an output OUT of the same LNA 2 is connected to the signal line 104 and, through this, to the input / output terminal 102.

[0040] Figure 3 illustrates a schematic of antenna 100 during transmission. In this case, the output RF signal is routed by the first switches 3 and 4 to a bypass line LB, excluding LNA 2 from the circuit, whose connections are shown in dashed lines as they are inactive. In the diagram in Figure 2, the aforementioned bypass line LB is shown in dashed lines, as it is not used during receiving.

[0041] In this way, RF signal paths are established between the radiating assembly 101 and the input / output connector 102 that include the LNA 2 during the receiving phases, and that exclude it during the transmitting phases. During these phases, the LNA 2 is not powered, since the radio 103 no longer supplies DC on the signal line 104.

[0042] During the RF signal receiving phases, the necessary DC power supply to the LNA 2 and to the first 3 and second 4 switches is supplied on the signal line 104 by the radio 103. The power required for the operation of the LNA 2 and the switches 3, 4 is drawn via completely known power supply circuits.

[0043] According to the invention, the self-powered amplifier device 1 also comprises auxiliary power supply means 5 for the aforementioned first 3 and second 4 switches (see figures 2 and 3), active during the RF signal transmitting phases and intended to supply electrical power to the switches 3,4 during such phases, since the same, like the LNA 2, can no longer be powered by the radio 103.

[0044] In particular, the auxiliary power supply means 5 comprises an RF / DC (radio frequency to direct current) converter 51 , connected to the signal line 104 and capable of taking a portion of this signal, not significant with respect to the power of the RF signal present on the line, to convert it into direct current at the nominal supply voltage of the first switches 3 and second switches 4.

[0045] The RF / DC converter 51 is therefore active only during the transmitting phases, when a high-power RF signal is present on the line, and can be built, in practice, according to one of the various AC / DC conversion techniques known to the average-experienced technician. In particular, it includes an RF signal rectifier, designed to rectify the signal current and transform it into direct current, at a voltage between 3 and 5.5 Vdc, necessary to ensure correct switching of the devices 3,4. The rectifier circuitry is chosen from configurations known to the average- experienced designer, and is appropriately sized to draw only the power strictly necessary to power the switches 3,4. The converter 51 also includes a stabilizing section, to provide them with their nominal supply voltage.

[0046] The output of the RF / DC converter 51 is connected to the power supply inputs of the aforementioned switches 3,4 by means of a very low drop-out “OR” device, also of a type known to the designer, to the circuit for drawing the DC from the line during reception normally provided for such components, with the aid of suitable means designed to allow both power supply via the DC supplied by the radio 103 during reception, and that supplied by the converter 51 during transmission.

[0047] To improve understanding of the power supply paths for power the switches 3,4 in the different operating phases of the antenna 100, in figure 3 the power supply line output from the RF / DC converter 51 is shown in solid lines, active during the transmitting phase, while in figure 2 this line is shown in dashed lines as it is not active.

[0048] It is important to note that switches 3 and 4, which have so far been identified in the text and figures as distinct and separate components, can also be assembled into a single device, typically specifically designed to perform the functions of LNA components, as described above. It is understood that, from a purely functional standpoint, the two components operate independently of each other in this case as well.

[0049] In order to ensure the necessary power supply to the switches 3,4 even during the transitory switching phase of the radio 103 between the receiving and transmitting phases, the power supply means 5 also include (see figure 4) an energy accumulator device 52, connected to the RF signal line 104 and to the first switch 3 and second switch 4, intended to accumulate energy during the receiving phases, and maintain the power supply to the same during the very short transitory periods between the receiving and transmitting phases.

[0050] The aforementioned energy storage device 52 preferably comprises a capacitor 53, connected to the RF signal line 104, in an “OR” configuration with the aforementioned RF / DC converter 51 , and with the interposition of insulating means 54; the latter are constituted by a high frequency impedance, and are intended to take part of the direct current component present on the RF signal line 104 during the receiving phases, to charge the capacitor 53 and therefore make an electrical charge available when, at the moment in which the radio 103 ceases to supply the direct current component at the end of a receiving phase, the aforementioned RF / DC converter 51 is not yet able to supply the auxiliary power to the switches 3,4. In this way, switches 3 and 4 are prevented from being left without power for a few moments, and therefore any risk of them keeping LNA 2 in circuit for a moment longer is avoided when the RF power signal for transmission is supplied on signal line 104, a situation which could seriously damage LNA 2 itself.

[0051] Also in this case, for greater clarity, the power supply lines of the switches 3,4 coming from the energy storage device 52 are shown in figure 4 with a solid line as they are active during the transient, while in figures 2 and 3 they are shown with a dashed line as they are not active.

[0052] It is understood that different solutions for the energy storage device 52 can be adopted without departing from the scope of the invention.

[0053] From the above it is clear that the self-powered amplifier device 1 allows the use, in an antenna equipped with amplification of the received signal by means of an LNA, electronic switches with very high switching speed, low noise and high durability and reliability, even in RF transceiver equipment in which the radio supplies a continuous component in line only during the RF signal receiving phases. However, it is understood that the above description is intended as an example and not as a limitation; therefore, any variations in detail that may be necessary for technical and / or functional reasons are hereby considered to fall within the same scope of protection defined by the claims reported below.

Claims

CLAIMS1. Self-powered amplifier device for a transceiver antenna, said antenna (100) comprising a radiating assembly (101 ) capable of transmitting and receiving radio frequency (RF) signals in the form of radio waves, and an input / output terminal (102) capable of allowing the connection of said antenna (100) to a radio equipment (103), said self-powered amplifier device (1 ) being characterised in that it comprises:- a low-noise RF amplifier (2), capable of amplifying an RF signal injected into its own input (IN) and making it available at its own output (OUT);- a first electronic switching device (3), electrically connected to said radiating group (101 ), to said input (IN) of the RF amplifier (2) and to a bypass signal line (LB);- a second electronic switching device (4), electrically connected to said terminal (102) by means of a signal line (104) internal to said antenna (100), to said output (OUT) of the RF amplifier (2) and to said bypass signal line (LB);- said first (3) and second (4) electronic switching devices being provided to define signal connections between said terminal (102) and radiating group (101 ) to include said RF amplifier (2) during the signal receiving phases, and to exclude it during the transmitting phases, by diverting the transmitted signal towards the aforementioned bypass signal line (LB);- power supply means (5) of said first (3) and second (4) electronic switching devices, comprising an RF / DC converter (51 ) connected to said signal line (104), suitable for taking from the same a part of the RF power signal during the transmitting phases and converting it into direct current, and also connected to said first (3) and second (4) electronic switchingdevices to supply them with electrical power during the aforementioned transmitting phases.

2. Amplifying device according to claim 1 , characterised in that said power supply means (5) further comprise an energy accumulator device (52), connected to said signal line (104) and to said first (3) and second (4) switching devices, intended to accumulate energy during said receiving phases and contribute to powering said first (3) and second (4) switching devices during the transition periods between receive and transmission.

3. Amplifier device according to claim 1 , characterised in that said RF / DC converter (51 ) includes a high frequency rectifier sized to rectify part of the current of said RF power signal and transform it into direct current, at a voltage between 3 and 5.5 VDC.

4. Amplifier device according to claim 2, characterised in that said energy accumulator device (52) comprises at least one capacitor(53), connected in “OR” configuration to the aforementioned RF / DC converter (51 ).

5. Amplifying device according to claim 4, characterised in that said energy accumulator device (52) also comprises insulating means(54), interposed between said capacitor (53) and said signal line (104), suitable for taking the direct component from the latter to charge the aforementioned capacitor (53).

6. Amplifying device according to claim 5, characterised in that, in said first (3) and second (4) switching devices, the transition between the powering of the same during the receiving and transmitting phases occurs by means of the supply of energy by the aforementioned capacitor (53)

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