DE3507779A1 - OVERLOAD PROTECTION FOR HF RECEIVERS - Google Patents

Description

TER MEER · MÖLLER · STEINMEISTER

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DESCRIPTION

The invention relates to overload protection according to the preamble of claim 1 and high-frequency reception sy star with such an overload protection.

There are many cases where a sensitive input circuit is exposed to excessive voltages, currents or currents Benefits must be protected. This applies, for example, to certain field effect transistors or other components to whose input only a voltage • 10 that is not of a certain size may be applied exceeds. The same applies to the receipt of certain recipients. For example, in weather radar systems the input range of a mixer circuit can be damaged by setting it too high Receives power emitted by nearby radio sources or generated by the weather radar system itself and is grasped again by this after reflection. Radar systems are particularly prone to overload, because they have an antenna with a double function, which emits both relatively high-energy pulses and receives very weak signals of the same shape. If such an antenna is damaged or broken, it is it is also possible that the high-energy pulses mentioned are not emitted in the desired manner but can be coupled directly to the input of the radar receiver.

Radar systems of the type mentioned are very difficult to protect against overload. For example, after a known protection method, the weather radar antenna rotated so that it does not cause damage Receives signals from other radar systems operating in the vicinity or as a result of reflections until a

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the aircraft carrying the radar system is relatively strong has left the frequented traffic area. A different and less successful method was used the protection of the radar system by switching off its supply. As soon as this, however, again is turned on, the above problem arises again. The entrance area of the radar system and with it its highly sensitive components in turn, damaged by excessive signals sent from nearby radio frequency sources will.

According to another known technique for protecting the entrance area of radar systems, a or several stages of pin diodes connected in parallel. A relatively high radio frequency signal over the Pin diodes are operated in the forward direction. The operation remains in the forward direction due to the diode capacitance is maintained. However, there are inherent limits to this solution, as the Pin diodes absorb power and therefore have to have a relatively high rated power. This means, that they respond relatively slowly, so that it is possible for a strong signal to break the protected circuit to reach before the diodes switch through. In addition, the pin diodes do not create a perfect one Short circuit, but only reduce the dynamic transverse or parallel impedance over the input area the circuit to be protected.

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It is often desirable in high frequency circuits and also practical to consider the relatively short wavelength of the signals passing through the circuit To make use of. For example, a transmission link can have a short-circuited or open end own while the other end depends on the

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effective electrical length of the transmission path appears as an open or short-circuited circuit. Similarly and according to the distance from gates along the transmission path can be either there is complete or no coupling between the gates. This phenomenon is used in circulators ^ Directional couplers and hybrid couplers exploited. The various effects can be used with Waveguides, cables, micro-striplines, striplines and known equivalent circuits that a corresponding transmission path simulate ^ can be generated.

The invention is based on the object of an overload protection device for securing a sensitive circuit of the type mentioned, through which an impermissibly strong signal is degraded or removed faster and more completely. is interrupted than is possible with the known systems.

The solution to this problem is given in brief in claim 1.

Advantageous developments of the invention are the Refer to subclaims.

According to the invention, an overload protection is created, with the help of which it is prevented that at its entrance adjacent radio frequency signals reach their output with excessively high power. That way will ensures the safe transmission and processing of useful signals in downstream circuits. The overload protection has a load distribution element, a detector device and a diverting or diverting device. The detector device is coupled to the input to a setting current as a function

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a signal exceeding a certain value on the Generate input. The deflection device is also with the input and additionally with the output, the Load distribution element and the detector device of the overload protection coupled - it receives the set current and, depending on this, directs the power appearing at the input from the output to the load distribution element.

The invention also relates to a radio frequency receiving system with an antenna, a high frequency power source and a load sharing element. The receiving system has a device for phase-shifted Control of at least a first, a second and a third gate. The first goal is with the Antenna and the second port connected to the power source. The first gate can be controlled in such a way that a connection can be established between it and the second and third port. Against the second and third gate controlled in such a way that a connection between them is prevented. In the receiving system is further comprising a processor unit that receives and receives signals having a predetermined distribution a detector signal is generated. In addition, an overload protection is provided, which is connected to the load distribution element, the third port and the processor unit is connected to signals supplied by the third port divert from the processor unit to the load balancing element if necessary. In this way, the Processor unit protected from excessively strong signals.

With the help of the overload protection according to the invention, a received signal from an input to a Output can be transmitted selectively. For this purpose, the overload protection uses a diverting device that runs between is arranged at the entrance and the load distribution element,

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in order to convey these signals or power. One The reflection device of the overload protection is connected to the diversion device, so that power at the reflection device is removed from the load distribution element can be reflected. Control means are used to change the extent of the reflection at the reflection device provided so that the overload protection can be adjusted and the power can be diverted from the input or from Output of the overload protection to the load distribution element, which destroys the existing power, is guaranteed.

By using an overload protection device of the type described above, a highly sensitive circuit can be effectively protected in that excessive power that is coupled in is diverted quickly and completely from the circuit to be protected to a load distribution element, which destroys the power. According to a preferred embodiment of the invention d is ^it connected input of the overload protection via a directional coupler to a node, which is the starting point for two quarter-wave branches. One branch extends in the direction of the circuit to be protected and is shunted which is formed by a first limiting diode. The other branch ends in the load distribution element, which is formed, for example, by a resistor. A controllable stub that is connected to the load sharing resistor has a further shunt, which is also formed by a limiting diode. This shunt is located at a point on the stub that is a quarter of a wavelength away from the load sharing resistor. Preferably, said diodes are forward biased with the aid of a Schottky diode detector, which by the

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Directional coupler is controlled. An excessive signal can therefore affect the existing overload protection circuit effectively remodel so that it is diverted to the load distribution element. 5

The overload protection is extremely fast because the Schottky diodes can be designed so that they respond immediately to a received excessive signal and a correction current or setting current produce. As a passive component to be designated overload protection can be designed so that it is in five up to twenty nanoseconds or even less, depending on the choice of the appropriate components, the received Redirects performance. Such an overload protection for 1.5 kilowatts, a pulse width of 16 Microseconds (duty cycle of 0.003) and a recovery time of 1.2 microseconds.

If the existing power is applied to an external terminating resistor switched, so the load distribution element is from the other components of the overload protection arranged separately, the overload protection can be produced using micro-stripline technology otherwise the micro striplines could be damaged. This technique allows about In addition, regardless of any unintentional loads as a result of mismatches, the processing of Signals or powers that are about an order of magnitude higher because the power redirection causes the real power at the diodes is an order of magnitude below the maximum nominal value of the diodes.

The following drawing shows exemplary embodiments of the invention. They show:

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Figure 1
Figure 2
Figure 3
Figure 4A

Figure 4B

a high frequency receiving system with a Overload protection according to the invention, a more detailed representation of the overload protection According to Figure 1, a circuit corresponding to Figure 2 with micro-striplines, a transmission path of the circuit of Figure 3, if signals from its input are passed to their output, and a further transmission path of the circuit of Figure 3, if signals from Input to be routed to a load balancing element.

Figure 1 shows a high-frequency receiving system, as it is used, for example, as a weather radar system in aircraft, and that at a frequency of 9.35 GHz works. Of course, such high-frequency receiving systems can also be used for other purposes used and operated at other frequencies. The embodiment described here works at frequencies (radio frequencies) above the audio range and below the infrared range. The radar system of Figure 1 has one with a first Port 14 connected antenna 10 and a second port 16 connected magnetron 12, the gates 14 and 16 belong to a phase shifter device, for example a waveguide circulator 18. Der Circulator 18 is operated so that the antenna 10 either with the magnetron 12 or with a third Gate 20 can connect, although between the third gate 20 and the magnetron 12, that serves as a high frequency power source, no connection will be produced. The waveguide gate 20 (third gate) is via a waveguide with a

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Coaxial cable connecting transition device 21 with the Input Jl of the overload protection connected, which has a protective device 24 and a load distribution element 26 owns. The interworking facility 21 may be a commercially available facility in which a Waveguide ends with a conductive part that serves as the inner line of a coaxial cable. The exit J2 of the protection device 24 is connected to the input of a processor circuit 28, which in the present case Case is, for example, the mixer stage of the weather radar system carried by an aircraft. These Mixer stage 28 and its associated circuits are intended to be provided by protection device 24 and the load sharing element 2 6 protected against excessive input signals or excessive power.

In FIG. 2, the above-mentioned overload protection is shown in more detail, which consists of the protective device 24 and the load distribution element 2 6, which in this case is an external one which is connected or grounded to ground Resistance is. The load distribution element 2 6 is connected to the protective device 24 via a connector J3 connected, which may be of the OSM type, for example. The input Jl, through the socket of a socket connector formed by the OSM type is connected to a port of the directional coupler 3 0 while the further gate of the directional coupler 3 0 is connected to the node A. The two others Corresponding ports of the directional coupler 13 are each separated by a matching resistor 32 of 50 ohms and connected to the input of a matching network 34. This adaptation network 34 is used to correct impedance mismatches between the individual components of the circuit arrangement. Of the Input Jl has a characteristic input impedance of 50 ohms, while the directional coupler 30

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a coupling loss of -3 3 dB between the input Jl and the input of the matching network 34 has. A directional coupler 30 of the type mentioned is generally known, for example from Members of Staff of the Radar School, M.I.T., Principles of Radar, McGraw-Hill Book Co., Inc. (1952), pages 834-839; Dr. Max Fogiel, Modem Microelectronics, Research and Education Association, New York, 1972, pp. 222-225. It can be seen from these references that Directional couplers made, for example, of waveguides, cables, striplines or microstriplines can exist. On the other hand, you can also use circuits having the same effects Induction coils and capacitors. In this embodiment, the directional coupler is 30 designed so that it allows duplex traffic between the input Jl and the node A.

The output of the adaptation network 34 is connected to a detector device, which also acts as a control device denote, connected, which is made up of a pair of conductive components working in the same direction 36 and 38 consists. The components 36 and 38 are preferably Schottky diodes, such as the DMJ type, their Anodes are each connected to the output of the matching network 3 4.

A low-pass filter has a bypass storage capacitor 39, which lies between ground or a reference potential and a connecting line that a test point TP connects to the two cathodes of the diodes 36 and 38. The filter device has a Induction or choke coil 40, which lies between the test point TP and the node C. About that In addition, there is a 68 ohm direct current return resistor 43 made of a carbon bond between ground and

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-18-arranged the reference potential and the test point.

According to the circuit structure described, a sufficiently large signal at the input Jl the diodes 36 and 38 switch in the forward direction so that they work as detectors and a voltage across the capacitor 3 9 as well generate a set current IB through induction coil 40 to node C.

The node C is parallel to the anodes via a beam guiding capacitor 42 of 10 pF (series connection) lying limiter diodes 44 and 46 connected, the cathodes of which are grounded or are at reference potential. With regard to the specified operating frequency, the diode 44 has a recovery time of 20 nanoseconds, while the Diode 46 has a recovery time of 10 nanoseconds. The diodes 44 and 46 can, for example, pin diodes or other suitable diodes. An induction coil 48 generating a direct current reversal lies between earth and ground. Reference potential and the connection line, which the anodes of the limiter diodes 44 and 46 and the output J2 (Socket of a plug connection) connects with each other.

The circuit arrangement according to Figure 2 has a signal diversion device, which is described in more detail below. The line A-C between the nodes A and C are referred to as the main transmission link and the third transmission link, respectively. This line A-C is preferably constructed as a quarter-wavelength transmission path through micro-striplines, although it goes without saying waveguides, cables, or other equivalent circuitry could also be used. A variable The semiconductor limiter diode 50, which is also referred to as a suppression, quenching or isolating device, forms the impedance can be. The anode of the limiter diode 50 is connected to the node C, while its cathode is grounded or is at reference potential. Example

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wise, the limiter diode 50 may be a pin diode with a Recovery time of 50 nanoseconds. Another quarter-wavelength transmission link A-B lies between nodes A and B and is referred to below as the first transmission link. This transmission line is structured similarly to the transmission path A-C. The node B is through a capacitor 52, which is identical to the capacitor 42, and via the output J3 (connector of the OSM type) with a 50 ohm matching termination connected, which is formed by the load distribution element 2 6. Line B-D forms another quarter-wavelength transmission link between nodes B and D and is referred to as the second transmission link, the similar to the other two A-C and A-B.

A diode 54 has its anode at the node D, while its cathode is connected to ground Reference potential is. Through this diode 54, which is referred to as a relief or reflection device can, another shunt is formed. The diode 54 is a semiconductor diode with variable impedance and may be identical to the aforementioned diode 50. A fourth transmission line, namely the line D-E, lies between the nodes D and E and is connected in series with the second transmission line B-D to to form a line termination. Preferably, the transmission link D-E is effectively half a wavelength long.

FIG. 3 shows a practical embodiment of the circuit according to FIG. 2 using micro-stripline technology. Of course, this circuit can also be constructed with discrete components, with the various Transmission links are formed by equivalent circuits, especially at low levels Frequencies. Alternatively, the circuit can also be constructed by waveguides, although this complicates the manufacture would. -

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The circuit shown comprises an aluminum frame 60 with four walls on which the three aforementioned inputs and Connectors Jl, J2 and J3 of the OSM type are mounted. The outer conductive hoods of connectors Jl, J2 and J3 are connected to the aluminum frame 60 by screwing.

The internal circuitry is on a micro-strip circuit board arranged comprising an aluminum base plate 62 which is electrically and mechanically connected to the frame is connected and has the same external dimensions as this. On the side of the frame opposite the plate 62 60, a correspondingly designed aluminum cover plate (not shown) is connected to the frame 60 by screws. The inner side of the base plate 62 is covered with a thin layer 64 of a low loss dielectric Material, preferably made of polytetrafluoroethylene, connected, which is about 0.254 mm thick. The different striplines on the dielectric layer 64 are formed by metal layers corresponding to the predetermined Circuit arrangement have been generated by a photochemical etching process. The components according to FIG Corresponding elements are provided in FIG. 3 with the same reference numerals as in FIG.

The majority of the striplines shown are like that dimensioned so that a characteristic impedance (or a characteristic impedance) of 50 ohms is obtained. Specifically the Strip line between the connectors J1 and J2 and the aforementioned transmission lines A-B, B-D, D-E and the

3Q path between connector J3 and node B. shaped so that they have the said characteristic impedance of 50 ohms. The width of this 50 ohm stripline is 0.787 mm. The strip line 3OA, which is formed between the elements 34A and 32 of the Directional coupler 30 is located.

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The directional coupler 30 has a strip conductor 30A, which is about 5.7 mm long and about from strip conductor 30B 0.889 mm away. The directional coupler 30 is also designed so that it has a coupling loss of -33 dB at an input frequency of 9.35 GHz has between the input Jl and the element 3 4A. The right end of the strip conductor 30A in Figure 3 is through the previously mentioned resistor 32, which is designed as a plate resistor, and which is connected to a grounded resistor Attenuator 66 is connected. The attenuator 66 consists of a metal layer on the

dielectric layer 64 rests and has a slot which is in connection with the aluminum base plate 62. This slot is approximately 3.3 mm long and 0.787 mm wide and has rounded ends. The slot is connected to the base plate 62 in that the attenuator 6 is soldered to the base plate 62.

The already mentioned matching network 3 4 is shown here as a capacitive shunt element 34A, namely as widening metallic attenuator to capacitively divert signals to the base plate 62 below. A stripline then leads from element 3 4A (shunt capacitor), which is also 0.787 mm wide, to the aforementioned Schottky diodes 36, 38, which represent a parallel combination and in a common housing are hermetically sealed by the manufacturer. Said strip conductor 3 4C between the components 34A and 36 is shunted about two thirds of its way towards diode 36, formed by a stripline induction element 3 4B which is connected to a grounded attenuator 68. The attenuator 68 in turn has a Slot for making a solder connection to the base plate 62. The strip conductor 34B is a quarter-wave DC reversing element, that as a throttle on the radio

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frequency range works. Components 3 4A and 34C form an impedance matching network through which the 50 ohm impedance of the strip line 3OA to the through the Schottky diodes 36, 38 formed lower impedance is adapted. The dimensioning of elements 34A and 34C is therefore carried out taking into account the impedance in the area of the diodes 36, 38.

Of the . Shunt storage capacitor 3 9 is through a

2 attenuator formed, which is about 1 mm in size.

The choke coil 40 between the shunt storage capacitor 39 and the node C consists of one Goldbrand 0.127 mm wide and 0.635 mm thick.

The DC return resistor 43 is between the attenuator 39 and a slot of an attenuator 70, which is used to ground it. A stripline induction element 48 with a width of 0.177 mm and a length of 6.14 mm connects the attenuator 70 with that strip line that runs between the connector J2 and the diode 46, namely on one Point closer to the diode. The diode is a normal cubic component with connection contacts formed on opposite surfaces. Its cathode side is connected to the base plate 62 via a solder joint, through a slot 46A located in the dielectric layer 64. The area 7 2 is grounded to prevent leakage currents or shunt currents from developing. The anode of diode 46 is connected to the micro stripline on each side of slot 46A by a pure gold ribbon (99.99% gold), which has a length of 0.127 mm and a diameter of 0.063 mm. Of course you can do this gold strips of appropriate dimensions can also be provided. A gap in the micro stripline between the diodes 44 and 50 is by means of the beam guiding capacitor 42

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bridged. The already mentioned diodes 44 and 50 are corresponding of diode 46 are also arranged in slots 44A and 50A, which are formed similarly to slot 46A are / so that their respective cathodes are also in corresponding Manner are connected to the base plate 62. The anodes of the diodes 44 and 50 are also the same Connected in a manner similar to diode 46 with a gold wire or strip of gold spanning slots 50A and 44A. The anode of the diode 50 is connected to the already mentioned node C and on the other hand via a line 40 to the Attenuator 39 connected. The micro-stripline between nodes C and A in turn represents the the previously mentioned quarter-wavelength transmission path and is in the illustrated embodiment approximately 4.826 mm long, which is determined by the operating frequency of 9.35 GHz. The is about the same length Micro-stripline running perpendicular to it, which extends from node A to node B. Between The further beam guiding capacitor 52 is soldered into the node B and the strip conductor 7 4. Of the On the other hand, strip conductor 74 is connected to connector J3. Between the nodes B and D is a Strip conductor, the length of which is the length of the between the Points A and B lying stripline corresponds. At node D there is a limiter diode 54, whose Cathode is soldered to the base plate 62 through a slot 54A. The anode of diode 54 is in turn connected to a gold ribbon or strip spanning the slot 54A. A subsequent Micro stripline between nodes D and E is about twice as long as the stripline between open at points B and D and at node E.

FIGS. 4A and 4B serve to explain the mode of operation of the overload protection, which is described below under With the help of Figures 1 to 3 will be explained again.

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According to FIG. 1, the circulator 18 can be controlled in such a way that he the high-frequency signals generated by the magnetron 12 in short pulses to the antenna 10 without a significant signal being coupled into the third gate 20. the Radiation reflected from objects is captured by the antenna and with the help of the circulator 18 into the goal directed. After passing through the connecting device 21, the received signal is transmitted via the input Jl of the protective device 24 supplied.

By a relatively small signal at input Jl of the protective device 24, a sufficient signal is not generated at the storage capacitor 39 '(see FIG. 2). Hence is a setting current JB flowing through induction coil 40

jL5 negligible · As a result, the diodes 54 and 50 cannot be operated in the forward direction and therefore have a very high input impedance, corresponding to the an open circuit. As a result, the circuit is not only at node E but also at Node D still appears to be open. A quarter wavelength away at node B appears the open circuit, however, as short-circuited via resistor 26. This short circuit at node B causes that the strip conductor A-B appears like an open circuit from the node A from. There are no more diodes or components are present via which the power is derived from the micro-stripline between the connectors J1 and J2 could be, the signals are transported between the named connectors without reflection. One

3Q equivalent circuit of the micro stripline below These conditions are shown in Figure 4A with node B grounded for one from node A. to be generated as an open circuit.

In the following it is assumed that the magnetron pulses fed to the antenna 10 are reflected by it into the gate 14 what, for example, if the

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Antenna 10 or a blockage may be the case. These pulses are therefore relatively strong and have a high power level. Corresponding pulses are obtained when the Antenna 10 receives signals from nearby radar stations or other transmitting stations. Also in In these cases, an impermissibly high power is transported via the gate 14. It becomes too strong a signal from gate 20 to the entrance or connector Jl. This signal can typically be around 10 watts per nano-second increase.

In this case, a significant amount of power is passed from the directional coupler 30 through the matching network 34 to the detector diodes 36, 38 transmitted. Due to the very fast rectification with the help of the mentioned diodes rapid charging of the capacitor 39 is achieved. As a result, a setting current IB is generated, the values can reach up to 6OmA, and that by the induction coil 40 and by the operated in the forward direction Diodes 54 and 50 flows. This setting current IB suddenly reduces the dynamic impedance of the diodes 54 and and creates an effective short circuit between their anodes and cathodes. The short circuits thus cause the micro striplines, as shown in Figure 4B, be connected to ground or a reference potential.

The nodes C and D are thus assigned by them Limiter diodes 50 and 54, as shown in Figures 2 and 4B, grounded. Since the transmission path A-C with its grounded node C is a quarter wavelength is ^ it appears from node A seen as open or as an open circuit. The same applies to the transmission link B-D with its grounded Node D, which also appears from node B as an open circuit. As a result, arises an undisturbed signal path from the input connector Jl via the transmission path A-B and the connector J3 to the load

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divider element 26. The power present at the input connector Jl can therefore be external

iin load distribution element 2 6 are destroyed or dismantled. The circuit part, which appears to be effectively open and is formed by the transmission path A-C, thus ensures for excellent isolation in order to avoid signals with impermissibly high power from the circuit 28 to be protected keep away.

Behind the transmission path A-C, that is between the node C and the output J2, there are additional diodes 44 and 46 (FIG. 2) are provided in order to ensure even better protection of a subsequent circuit. These Diodes conduct power leaking through link A-C during the rise of the input signal by operating them in the forward direction through the power leaked through. You own one certain capacitance, so that they remain in this state for power dissipation and each reaches the output J2 Signal is only very small. The diode 44, and particularly the diode 46, can have a very high response as they do not need to be used to derive high performance.

If the impermissibly high signal at the input Jl of the protective device 24 disappears, all diodes return to their relative non-conductive state. For example, the diodes 44 and 46 can be discharged through the inductor 48. The same applies to the capacitor 39 and the diodes 50 and 54, which are discharged via the resistor 43, which is effectively connected in parallel with them.

In the embodiment described above, the setting current IB can be very fast, for example within from 5 to 20 nanoseconds. The return of the circuit to the normal state takes a little longer, for example up to 1.2 microseconds, and is a Function of the pulse width and the power level. the

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The recovery time of the circuit is determined, among other things, by the time constant that is dependent on the resistor 43. About that In addition, however, other factors are also of influence, for example the recovery times of the diodes 44, 46, 50 and 54. In particular, the recovery times of the last-mentioned diodes 50 and 54 are important. Are these elements mentioned discharged, so is with the help of the circuit according to the invention, as described above, power from the input Jl to Exit J2 transported. In this case, no power reaches the load distribution element 2 6.

The circuit according to the invention can of course in be modified or changed in many ways. For processing signals with different levels of power For example, the nominal power of the diodes or more or fewer diodes can be connected in parallel to one another will. In addition, it is possible to change the size of the micro-stripline while changing the dielectric constant of the underlying non-conductive material. While in Figures 2 and FIG. 3 shows a directional coupler 30 for controlling the diode detector for generating the setting current IB is, according to another embodiment, another coupling technique can also be used, for example includes an ohmic connection. In addition, in many cases, the quarter wavelengths or half-wavelength transmission links can be extended by a multiple of half the wavelength, without affecting the effectiveness of the circuit. Instead of a characteristic impedance of 50 ohms, As described, it is of course also possible to use other impedance values in other exemplary embodiments Select. The circuit also does not need to be built up by micro-striplines, discrete and interconnected wired components, waveguide systems, stripline systems or coaxial cable systems can also come into play, which depends on the respective

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Addresses requirements such as processing performance, operational safety, weight and size, etc. The electric and geometric sizes of the individual components can also be used depending on the frequency to be processed, the bandwidth, the power to be processed, the temperature stability, the accuracy, the insensitivity against interference, the requirements for the isolation, etc. are changed. It is also suitable The circuit described is not only used for securing radar systems, but can also be used in general for securing any circuit that receives oscillating signals at its input. The short circuits mentioned within the circuit, not only through the diodes described, but also through other components, including transistors or other fast switches. By a diode short circuit or a In addition, a corresponding through-connection can be generated that appears to be open, so that the Length of an assigned transmission link can be changed by using either an open or a short-circuited diode a circuit that appears to be open or short-circuited is generated.

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Claims (26)

3507773 TER MEER-MÜLLER-STEINMEISTER PATENTANWÄLTE- EUROPEAN PATENT ATTORNEYS Dipl.-Chem. Dr. N. ter Meer Dipl. Ing. FE Müller Mauerkircherstrasse 45 D-8000 MUNICH 80 Dipl. Ing. H. Steinmeister Artur-Ladebeck-Strasse 51 D-4800 BIELEFELD 1 Mü / Ur / b Case: A-1192 March 05, 1985 LITTON SYSTEMS, INC. 360 North Crescent Drive Beverly Hills, California 90210 U.S.A. Overload Protection for RF Receivers Priority: March 15, 1984 U.S.A. No. 589,812 (P) CLAIMS 1. Overload protection for a high frequency receiver, marked by - At least one load distribution element (26), - A detector circuit (36,38) connected to the input (Jl) of the overload protection for generating a Current setting (IB), if the input signal at the overload protection exceeds a predetermined value, and through - one with the input (Jl) and output (J2) of the transfer TER MEER ■ MÜLLER · STEINMEISTER -2- load protection as well as deflection device connected to the load distribution element (26) and the detector circuit (36, 38), the one present at the input (Jl) of the overload protection when the set current (IB) is received Power from its output (J2) reverses to the load distribution element (26). 2. Overload protection according to claim 1, characterized in that the deflection device is connected to the detector circuit (36, 38) Has elements (50,54) with variable impedance to take over the setting current (IB), and that the elements (50,54) additionally with the input '(Jl) for power redirection when receiving the set current (IB) are connected. 3. Overload protection according to claim 2, characterized by a between the detector circuit (36,38) and the elements (50,54) Low-pass filter (39, 40) arranged with variable impedance to separate the low-frequency and direct-current components the set current (IB). 4. Overload protection according to claim 3, characterized in that the detector circuit (36, 38) is conductive in the same direction Contains components. 5. Overload protection according to one of claims 2 to 4, characterized in that the elements (50,54) with variable impedance by Semiconductor components are formed. TER MEER · MÜLLER ■ STEINMEISTER 07 -3- 6. Overload protection according to one of claims 1 to 5, characterized in that the Deflection device contains relief or reflection elements (54) which are connected to the load distribution element (26) are, and when receiving the set current (IB) (26) open the signal path running through the load distribution element. 7. Overload protection according to claim 6, characterized in that the deflection device contains separating means (50) which the Disconnect the input (Jl) of the overload protection from the output (J2) 'when you receive the setting current (IB). 8. Overload protection according to one or more of the claims 1 to 7, characterized in that the deflection device - A first transmission path (A-B) for signal transmission between the input (Jl) and the load distribution element (26) and - A second transmission path (B-D) for signal transmission between the relief element (54) and contains the load distribution element (26) and that - The first and second transmission links each have effective lengths that are greater than one eighth are the wavelength of the signal passing through it. 9. Overload protection according to claim 8, characterized in that the effective length of the first transmission link (A-B) is an odd multiple of the quarter wavelength of the signal. ORIGINAL INSPECTED TER MEER · MÜLLER · STEINMEISTER _ 0773 -4- 10. Overload protection according to claim 8 or 9, characterized in that the effective length of the second transmission path (B-D) an odd multiple of the quarter wavelength of the Signal is. 11. Overload protection according to one or more of the claims 1 to 10, characterized in that the deflection device has a third transmission path (AC) for signal transmission, which is arranged between the separating means (50) and the connection between the input (Jl) and the first transmission path ( ¹ AB), and that the third transmission link (AC) has an effective length that is an odd multiple of the quarter wavelength of the signal. 12. Overload protection according to claim 11,
characterized in that the deflection device has a fourth transmission path (DE) which is open at one end and connected at its other end to the connection point between the relief elements (54) and the second transmission path (BD), and that the fourth transmission path (DE ) has an effective length that is a multiple of half the wavelength of the signal passing through it. 13. Overload protection according to one or more of the claims 1 to 12, characterized in that it has a directional coupler (30) with two pairs of ports has, with duplex traffic occurring between the gates of each pair that the gates of a pair with the Entrance (Jl) and the deflection device are connected, and that separated therefrom at least one gate of the other Pair is connected to the detector circuit (36,38). TER MEER · MÜLLER · STEINMEISTER η π η 14. Overload protection according to claim 13,
characterized in that at least one limiting diode (44, 46) is arranged between the connection of the deflection device to the output (J2) of the overload protection and a reference potential. 15. Overload protection according to one or more of the claims 1 to 14, characterized in that the detector circuit responds quickly Possesses Schottky diodes. 16. Overload protection according to one or more of the claims 6 to 15, characterized in that that the relief elements (54) and the separating elements (50) are impedance variation diodes, which by the Setting current (IB) can be operated in the forward direction. 17. Overload protection according to one or more of the claims 1 to 16, characterized in that it is in stripline, microstrip or Coaxial cable technology is built up. 18. High frequency transmitting and receiving device, with - a high frequency power source (12), - an antenna (10), and - A circulator (18) with at least three gates (14,16,20), of which a first gate (14) with the Antenna (10) and a second port (16) with the high frequency power source (12) is connected, the second and a third gate (20) each being connectable to the antenna (10), but not among themselves are, characterized in that the third gate (20) with an overload protection after a ORIGINAL ii'wFE TER MEER · MÜLLER · STEINMEISTER -6-
or more of claims 1 to 17 is connected. 19. High frequency transmitting and receiving device, with - a high frequency power source (12), - an antenna (10), -a device for the phase-shifted control of at least a first (14), second (16) and third gate (20), the first gate (14) with the antenna (10) and the second gate (16) with the High-frequency power source (12) are connected, the first gate (14) can be controlled so that a Connection between him and the other two gates can be established, and the second and third Gate (16, 20) are controlled so that there is no connection between them, and with - A processor unit (28), which is dependent on generates output signals from received signals with a predetermined distribution, characterized in that between the third port (20) and the processor unit (28) an overload protection according to one or more of claims 1 to 17 is arranged, wherein the third gate (20) with the input (Jl) of the overload protection and its output (J2) with the input the processor unit (28) are connected. 20. High-frequency transmitting and receiving device according to Claim 19, characterized in that the overload protection is provided by a protective device (24) formed and the load distribution element (26) is arranged outside the protective device (24). TER MEER · MÜLLER ■ STEINMEISTER -7- 21. High frequency transmitting and receiving device according to Claim 20, characterized in that the device for the phase-shifted control of the The goal of a waveguide circulator is that the protective device (24) is constructed as a micro-stripline circuit is, and that between the waveguide circulator and the input (Jl) of the protection device (24) a connector (21) is arranged to create a waveguide-microstrip line transition. 22. High frequency transmitting and receiving device according to Claim 21, characterized in that the first and second transmission links (A-B, B-D) Are strip conductors each having an effective length of a quarter wavelength, and that a shunt generating diode is provided as a relief element. 23. High frequency transmitting and receiving device according to Claim 22, characterized in that the third transmission link (A-C) is a stripline is, which has an effective length of a quarter wavelength, and that the fourth transmission link (D-E) is a stripline with an effective Length is a multiple of half the wavelength. 24. High frequency transmitting and receiving device according to Claim 23, characterized in that between the input (Jl) and the output (J2) the Protection circuit (24) a straight main transmission path through a strip conductor, its interruptions TER MEER · MÜLLER. STEINMEISTER - - ■ -8th- are bridged by conduction bands or strips, is formed. 25. High frequency transmitting and receiving device according to a or several of the preceding claims, characterized in that further control means for changing the reflectivity of the relief and / or separating means (54 or 50) are available. 26. High-frequency transmitting and receiving device according to one or more of the preceding claims, characterized in that the second and fourth transmission links (B-D, D-E) form a common stub line (B-E), whose effective length is three quarters of the wavelength of the signal passing therein, and that a shunt (54) is provided in its central region in order to short-circuit it at an effective distance of a quarter wavelength from the load distribution element (26).