Radio frequency lightning protection circuit with feed

Abstract

The invention relates to a radio frequency lightning protection circuit with feed, which comprises a signal input end IN, a signal output end OUT, an inductor L and a transient voltage suppressor TVS, one end of the inductor L is connected between the signal input end IN and the signal output end OUT, the other end of the inductor L is connected with a bidirectional transient voltage suppressor TVS, and the other end of the bidirectional transient voltage suppressor TVS is grounded; the reverse working voltage of the bidirectional transient voltage suppressor TVS is higher than the feed voltage and lower than the lightning voltage. The junction capacitor Cj of the TVS diode is ingeniously adopted, and the inductor L and the junction capacitor Cj are reasonably arranged, so that radio-frequency signals are normally transmitted. And meanwhile, the reverse working voltage of the TVS is higher than the feed voltage, the TVS diode is in an open circuit state during signal transmission, a radio frequency signal and feed current normally pass through, and when lightning pulses are injected, the TVS diode is instantaneously conducted to discharge lightning energy, so that the lightning protection function is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of communication lightning protection, and particularly relates to a feed-through RF lightning protection circuit. Background Art

[0002] Figure 1 Shown in the figure is an existing feed-through lightning protection circuit. This circuit consists of many components, has a complex circuit, occupies a large space, and cannot meet the usage requirements of equipment with a compact structure. When it is necessary to implement the signal transmission of Beidou satellite signals and GPS signals and airborne transient lightning protection in an airborne pod, due to the compact structure, the above-mentioned lightning protection circuit that occupies a large space cannot meet the usage requirements. Summary of the Invention

[0003] To solve the above problems, the present invention provides a feed-through RF lightning protection circuit with a novel structure, which has the characteristics of fewer components, a simple circuit, and a small occupied space while meeting the lightning protection requirements during the transmission of RF signals and DC signals.

[0004] The object of the present invention and the technical problem to be solved are achieved by adopting the following technical solutions. A feed-through RF lightning protection circuit according to the present invention includes a signal input terminal IN, a signal output terminal OUT, an inductor L, and a transient voltage suppressor diode TVS. One end of the inductor L is connected between the signal input terminal IN and the signal output terminal OUT, and the other end is connected to the bidirectional transient suppression diode TVS. The other end of the bidirectional transient suppression diode TVS is grounded; the reverse working voltage of the bidirectional transient suppression diode TVS is higher than the feed voltage and lower than the lightning voltage.

[0005] The object of the present invention and the technical problem to be solved can also be further achieved by adopting the following technical measures.

[0006] In the above-mentioned feed-through RF lightning protection circuit, the inductance of the inductor L is not greater than 50 nH.

[0007] In the above-mentioned feed-through RF lightning protection circuit, the resonant frequency of the LC series circuit formed by the inductor L and the bidirectional transient suppression diode TVS is far from the frequency of the RF signal to be transmitted, so that there are low insertion losses and voltage standing wave ratios during the transmission of the RF signal. In the above-mentioned feed-through RF lightning protection circuit, the resonant frequency of the LC series circuit can be made different by adjusting the parameters of the inductor L and the bidirectional transient suppression diode TVS to meet different RF signal transmission requirements.

[0008] The present invention has obvious advantages and beneficial effects compared with the prior art. By means of the above technical solutions, the present invention can achieve considerable technical progressiveness and practicality, and has wide industrial utilization value. It has at least the following advantages:

[0009] The present invention ingeniously utilizes the junction capacitance Cj of a TVS diode, reasonably sets the inductor L and the junction capacitance Cj, enabling the normal transmission of radio frequency signals. Meanwhile, by taking advantage of the fact that the reverse working voltage of the TVS diode is higher than the feeding voltage, the TVS diode is in an open state during signal transmission, allowing the radio frequency signal and the feeding current to pass through normally. And when a lightning pulse is injected, the TVS diode conducts instantaneously to discharge the lightning energy, thus achieving the function of lightning protection.

[0010] The device components of the present invention are few and the circuit is simple, which can meet the usage requirements of small spaces and has the characteristics of low cost. Brief Description of the Drawings

[0011] Figure 1 is a schematic diagram of the composition of an existing lightning protection circuit with feeding;

[0012] Figure 2 is a schematic diagram of the composition of the lightning protection circuit with feeding and radio frequency of the present invention;

[0013] Figure 3 is an equivalent circuit diagram of the lightning protection circuit with feeding and radio frequency of the present invention;

[0014] Figure 4 is the simulated insertion loss curve of the lightning protection circuit with feeding and radio frequency of the present invention;

[0015] Figure 5 is the simulated reflection coefficient curve of the lightning protection circuit with feeding and radio frequency of the present invention;

[0016] Figure 6 is the actual insertion loss test curve of the lightning protection circuit with feeding and radio frequency of the present invention;

[0017] Figure 7A is the actual voltage standing wave ratio test curve at the input end of the lightning protection circuit with feeding and radio frequency of the present invention;

[0018] Figure 7B is the actual voltage standing wave ratio test curve at the output end of the lightning protection circuit with feeding and radio frequency of the present invention;

[0019] Figure 8 is the level 3 waveform 3 lightning test curve of the lightning protection circuit with feeding and radio frequency of the present invention;

[0020] Figure 9 is the level 4 waveform 4 lightning test curve of the lightning protection circuit with feeding and radio frequency of the present invention. Detailed Embodiment

[0021] To further elaborate on the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following, in combination with the drawings and preferred embodiments, details the specific embodiment, structure, features and effects of the lightning protection circuit with feeding and radio frequency proposed according to the present invention.

[0022] Please refer to Figure 2 , the feed-in radio frequency lightning protection circuit of the present invention includes a signal input terminal IN, a signal output terminal OUT, an inductor L, and a transient voltage suppressor diode TVS. One end of the inductor L is connected between the signal input terminal IN and the signal output terminal OUT, and the other end is connected to the bidirectional transient suppression diode TVS. The other end of the bidirectional transient suppression diode TVS is grounded; the reverse working voltage of the bidirectional transient suppression diode TVS is higher than the feed voltage and lower than the lightning voltage. To prevent the inductive reactance from being too large when the inductor L is too large, resulting in an increase in the protection voltage of the circuit, the impedance of the inductor L in the present invention is not higher than 50 nH. When the feed-in radio frequency lightning protection circuit of the present invention transmits radio frequency signals, the radio frequency signals are input from the signal input terminal IN. Due to the high-frequency blocking effect of the inductor L, the radio frequency signals are directly output from the signal output terminal OUT under the action of the inductor L. At the same time, since the reverse working voltage of the bidirectional transient suppression diode TVS is higher than the feed voltage, the feed current cannot pass through the bidirectional transient suppression diode TVS, and the bidirectional transient suppression diode is in an open state, so that the feed current is also directly output from the signal output terminal OUT together with the radio frequency signals. When a lightning pulse is injected from the signal input terminal IN, due to the low transmission rate of lightning and the inductance of the inductor L not being higher than 50 nH, the inductor L can be short-circuited during the transmission of lightning. And because the voltage of lightning is much higher than the reverse working voltage of the bidirectional transient suppression diode TVS, the bidirectional transient suppression diode TVS conducts instantaneously, discharging the lightning energy to the ground GND to protect the load at the output end and achieving the function of lightning protection.

[0023] In this circuit, the series connection of the inductor L and the bidirectional transient suppression diode TVS forms an LC series circuit based on the junction capacitance Cj of the inductor L and the TVS. The equivalent circuit is shown in Figure 3 . The resonance frequency of this LC series circuit will affect the transmission impedance of radio frequency signals at different frequencies, and thus affect the transmission performance of radio frequency signals. Only when the resonance frequency of this LC series circuit makes the impedance at the frequency of the transmitted radio frequency signal larger, the radio frequency signals will not be transmitted to the ground GND through this LC series circuit, but will be directly output from the signal output terminal OUT. The resonance frequency of the LC series circuit in the present invention changes with the changes of the inductor L and the bidirectional transient suppression diode TVS. By adjusting the parameters of the inductor L and the bidirectional transient suppression diode TVS, an LC series circuit with different resonance frequencies can be obtained, so as to meet the transmission requirements of radio frequency signals at different frequencies.

[0024] Please refer to Figure 4 and Figure , which are respectively the insertion loss and reflection coefficient simulations obtained by software for the feed-in radio frequency lightning protection circuit of the present invention. ​The horizontal coordinate represents frequency, and the vertical coordinate represents insertion loss. The resonant frequency of the LC resonant circuit composed of inductor L and TVS in series is 16.4 MHz. The curve in the figure is the insertion loss of the circuit under different RF signal transmissions. It can be seen from this figure that the closer the frequency of the transmitted RF signal is to the resonant frequency of the LC resonant circuit, which is 16.4 MHz, the greater the insertion loss of the circuit. When the RF signal frequency is equal to the resonant frequency of the LC resonant circuit, the insertion loss reaches the maximum, such as point m1 in the figure. The frequency of its transmitted signal is 16.4 MHz, and the loss is as high as 68.758 dB. When the RF signal frequency is far from the resonant frequency of the LC resonant circuit, the insertion loss approaches zero infinitely, such as point m2 in the figure. The frequency of its transmitted RF signal is 1.600 GHz, and the insertion loss is 0.012 dB. Thus, it can be seen that the present invention can adjust the parameters of the inductor L and the bidirectional transient suppression diode TVS so that the resonant frequency of the LC resonant circuit is far away from the frequency of the RF signal to be transmitted, resulting in a small insertion loss during RF signal transmission and good signal transmission performance. In the embodiment of the present invention, to make the resonant frequency of the LC resonant circuit avoid the frequency of the RF signal to be transmitted, the frequency of the RF signal transmitted by the circuit of the present invention is greater than 30 times the resonant frequency.

[0025] ​ For the reflection coefficient of the circuit transmitting RF signals with different frequencies when the resonant frequency of the LC series circuit is 16.4 MHz. It can be clearly seen from this figure that the closer the frequency of the RF signal is to the resonant frequency, the greater the reflection coefficient of the circuit. When the frequency of the RF signal is equal to the resonant frequency, as shown by point m4 in the figure, the reflection coefficient of the circuit is 1 at this time. When the frequency of the RF signal is far from the resonant frequency, as shown by point m3 in the figure, its frequency is 1.600 GHz, and the reflection coefficient is 0.053.

[0026] From ​ and ​ it can be known that when the resonant frequency of the LC series circuit is 16.4 MHz, the insertion loss of the circuit of the present invention at a frequency of 1.6 GHz is 0.012 dB, and the reflection coefficient Γ = 0.053. The voltage standing wave ratio is calculated by the following formula: VSRW = (1 + Г) / (1 - Г) = 1.11. Thus, it can be seen that the circuit of the present invention has a small insertion loss and a small voltage standing wave ratio, and has good signal transmission performance.

[0027] Build a circuit and actually test the insertion loss and voltage standing wave ratio. ​It is the actual test curve of the insertion loss. At this time, the capacitance of the inductor L in the circuit is 47 nH, and the bidirectional transient voltage suppression diode TVS is the SMBJ6.0CA diode. At this time, the resonance frequency of the LC circuit composed of the inductor L and the bidirectional transient voltage suppression diode TVS is 16.000 MHz. It can be seen from this test curve that when the frequency of the radio frequency signal is 1.600 GHz, the insertion loss is 0.24 dB; when the frequency of the radio frequency signal is 16.000 MHz, the insertion loss is 44.49 dB. Obviously, this circuit has a lower insertion loss when transmitting signals with frequencies far from the resonance point frequency. ​ and ​ are respectively the voltage standing wave ratio test curves at the input end and the output end of the actual measured circuit of the present invention. It can be seen from the above curves that when the frequency of the radio frequency signal is 1.600 GHz, the input end standing wave ratio is 1.08, and the voltage standing wave ratios at the input end and the output end of the circuit signal are both 1.08. When the frequency of the radio frequency signal is 400.000 MHz, the voltage standing wave ratios at the input end and the output end of the circuit signal are both 1.5. When the frequency of the radio frequency signal is 2.500 GHz, the input end voltage standing wave ratio is 1.4, and the output end voltage standing wave ratio is 1.39. It can be seen from the above measured insertion loss and voltage standing wave ratio curves that the circuit of the present invention has a small insertion loss and voltage standing wave ratio. Especially when transmitting radio frequency signals around 1.600 GHz, the insertion loss and voltage standing wave ratio reach the minimum, and the signal transmission effect is the best.

[0028] Please refer to ​ and ​ , which is the curve graph of the lightning actual measurement of the circuit of the present invention. It can be seen from the figure that whether injecting the lightning pulse of level 3 waveform 3 or the lightning pulse of level 3 waveform 4, the circuit of the present invention has a good lightning protection effect.

[0029] The above is only a preferred embodiment of the present invention, and it does not impose any form of limitation on the present invention. Although the present invention has been disclosed above with the preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to it as equivalent embodiments within the scope of the technical solution of the present invention. However, as long as it does not depart from the content of the technical solution of the present invention, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A radio frequency lightning protection circuit with feeder, characterized in that: The device comprises a signal input terminal IN, a signal output terminal OUT, an inductor L and a transient voltage suppressor (TVS). One end of the inductor L is connected between the signal input terminal IN and the signal output terminal OUT, and the other end is connected to a bidirectional transient voltage suppressor (TVS). The other end of the bidirectional transient voltage suppressor (TVS) is grounded. The reverse operating voltage of the bidirectional transient voltage suppressor (TVS) is higher than the feed voltage and lower than the lightning voltage.

2. The radio frequency lightning protection circuit with feeder according to claim 1, characterized in that: The inductance of the inductor L is not greater than 50nH.

3. The radio frequency lightning protection circuit with feeder according to claim 1, characterized in that: The resonant frequency of the LC series circuit formed by the inductor L and the bidirectional transient suppression diode TVS connected in series is far away from the frequency of the radio frequency signal to be transmitted.

4. The radio frequency lightning protection circuit with feeder according to claim 3, characterized in that: The frequency of the radio frequency signal to be transmitted is greater than 30 times the resonant frequency of the LC series circuit.

5. The radio frequency lightning protection circuit with feeder according to claim 3, characterized in that: The parameters of the inductor L and the bidirectional transient suppression diode TVS can be adjusted to enable the LC series circuit to have different resonant frequencies to adapt to different RF signal transmission requirements.

6. The radio frequency lightning protection circuit with feeder according to claim 3, characterized in that: When the frequency of the radio frequency signal is 1.6 GHZ, the capacitance of the inductor L is 47 nH, the bidirectional transient suppression diode TVS is an SMBJ6.0CA diode, and the resonant frequency of the LC series circuit composed of the inductor L and the bidirectional transient suppression diode TVS is 16.000 MHZ.

Images