EP0588179A1 - Device for operating a wideband phased array antenna - Google Patents

Abstract

The invention relates to a circuit arrangement for operating a wideband phased array antenna. In this case, the associated individual antennas are driven by mixer arrangements which enable highly accurate, reliable and cost-effective phase changing. <IMAGE>

Description

The invention relates to a circuit arrangement for operating a broadband phase-controlled group antenna according to the preamble of patent claim 1.

A phase-controlled group antenna consists of a plurality of individual antennas, generally arranged in a matrix, which are designed as transmitting and / or receiving antennas. If, for example, a common transmission signal is now applied to these individual antennas, the direction of the transmission signal (transmission lobe) emitted by the group antenna depends on the electrical phase differences set between the individual antennas. The same applies to the so-called receiving lobe of the group antenna when receiving electromagnetic signals.

In some applications, e.g. in directional radio and / or radar technology, it is necessary to make the transmitting and / or receiving lobe pivotable. The necessary change in the phase differences is carried out with adjustable phase actuators. Furthermore, it is often necessary to design the group antenna as broadband as possible so that transmission and / or reception band can be transmitted and / or received in the broadest possible range.

The invention is based on the object of specifying a generic circuit arrangement which makes it possible to use a phase actuator which is inexpensive to produce and precisely adjustable to produce the widest possible group antenna with a transmitting and / or receiving lobe which can be pivoted with high precision.

This object is achieved by the features specified in the characterizing part of patent claim 1. Advantageous refinements and / or further developments can be found in the subclaims.

A first advantage of the invention is that a phase actuator is used which is essentially tuned to a frequency. Such a phase actuator can be produced inexpensively and reliably, especially in industrial mass production, and has a high phase and amplitude accuracy in a reproducible manner.

A second advantage consists in the fact that when the phase adjusting element is adjusted, any changes in amplitude that may occur bring about negligible changes in the transmitting and / or receiving lobe.

A third advantage is that the transmission and / or reception lobe (directional characteristic) of the group antenna can be set with high precision and with a high main to secondary lobe ratio, and that this setting is retained essentially over the entire swiveling range of the transmission and / or reception lobe.

A fourth advantage is that several transmitting and / or receiving lobes can be pivoted independently of one another with a single group antenna.

FIG. 1

eine vorgeschlagene Schaltungsanordnung mit einen breitbandig arbeitenden Phasenstellglied;

FIG. 2-5

Ausführungsbeispiele zur Erläuterung der Erfindung.

The invention is explained in more detail below on the basis of exemplary embodiments with reference to schematically illustrated figures. Show it:

FIG. 1

a proposed circuit arrangement with a broadband phase actuator;

FIG. 2-5

Exemplary embodiments for explaining the invention.

FIG. 1 shows a proposed circuit arrangement which works with a broadband phase actuator, which can be produced using monolithic technology and which is particularly suitable for operating an active (transmitting and / or Receiving) single antenna is suitable. Such an active individual antenna consists of a passive transmitting and / or receiving individual antenna which is tuned to the frequency band to be transmitted and / or received, for example the frequency range from 11 GHz to 13 GHz. A transmitting and / or receiving amplifier is coupled to these in the immediate vicinity. Such an active individual antenna, given as an example, can be connected to the input / output port designated P4 below.

To explain the proposed circuit arrangement according to FIG. 1 it is assumed that at the further input / output port P1 a signal to be transmitted in a first intermediate frequency range, e.g. has a center frequency of 3 GHz and a bandwidth of 2 GHz. This intermediate frequency signal passes through an adapted bandpass filter BPZF to an input of a first mixer M1, which e.g. as a bidirectional mixer, e.g. is designed as a diode mixer. At another input of the first mixer M1 there is an oscillator signal generated by an oscillator OSC, which e.g. has a frequency of 9 GHz. A so-called upward mixing takes place in the first mixer M1, so that a signal is generated in the first intermediate frequency range already mentioned. This signal arrives at the input / output port P4 already mentioned via a further bandpass filter BPA and a phase actuator PH and can be connected to an active individual antenna.

The oscillator signal is made available to further transmission / reception modules via a branch VER, so that phase coherence is ensured. This is shown in FIG. 1 represented by the connecting lines starting from the branch VER.

The circuit arrangement can also be used in the reverse direction, that is to say that a received signal present at the input / output port P4 is converted into the first intermediate frequency range by a so-called downmixing in the first mixer M1 and is then at the input / output port P1 for further processing at.

This circuit arrangement has the disadvantage that the phase actuator PH must be very broadband, that is to say it must encompass at least the entire frequency range of the transmission or reception frequency. In addition, a high amplitude and phase accuracy should be achieved when adjusting the phase actuator PH. At the same time, these requirements can only be met at high cost and require a large amount of circuitry and space for the phase actuator PH. Furthermore, a high expenditure for the calibration, i.e. the compensation of possible phase and amplitude errors in the individual modules is necessary.

These disadvantages can be avoided by a circuit arrangement according to FIG. 2. This differs from that according to FIG. 1 in that the phase actuator PH is arranged in the oscillator path. An amplifier V connected downstream of the phase control element PH is only used for impedance matching and / or for decoupling the signals and for generating the power required to control the mixer M1. However, this seemingly minor change has significant advantages. Because that Phase actuator advantageously only needs to be tuned to one frequency, namely the oscillator frequency. Such a phase actuator PH can be used, for example, as a switchable filter structure according to FIG. 5 be formed. Such a phase actuator necessarily has at least a phase shift of 360 °. Furthermore, any changes in the amplitude of the amplitude of the oscillator signal that may occur during a phase adjustment have a negligible effect at all, since an amplitude limitation is necessarily present in the first mixer M1 during the mixing.

FIG. 3 shows a circuit arrangement in which no phase actuator PH corresponding to FIGS. 2 and 5 is required in the oscillator path. The oscillator signal supplied to the first mixer M1 is also generated by mixing. For this purpose, a signal is generated in the oscillator OSC, for example with a frequency of 6 GHz. This is fed to a first input of a second mixer M2, which is also a diode mixer, for example. Furthermore, the signal of the oscillator OSC is also made available to all other active transmit / receive modules, so that phase coherence is ensured. The synthesizer DDS generates a signal, for example at a fixed frequency of 3 GHz, which is coupled to the frequency and the phase of a signal emitted by a reference oscillator REF. This signal is common to all S / E modules (coherence). The output signal generated by the synthesizer DDS is applied to a second input of the second mixer M2. The actual oscillator signal is then generated at its output, which has a frequency of 9 GHz, for example. Because of this mixture, this is the actual oscillator signal within a wide range of frequencies, for example from 8 GHz to 10 GHz, as well as in the phase position, can be changed with high precision. This actual oscillator signal is then fed to the first mixer M1 via a bandpass filter BPOS and a (driver) amplifier V.

The circuit arrangement according to FIG. 3 advantageously enables a precisely repeatable and rapid setting of the frequency and phase position of the actual oscillator signal, e.g. with the help of a data processing system (microprocessor), not shown, through which e.g. the synthesizer DDS and the oscillator OSC is adjusted. With such a circuit arrangement e.g. a quick change in the frequency of the actual oscillator signal is possible, e.g. a so-called multi-beam operation in time-division multiplex operation is possible.

FIG. 4 shows an exemplary circuit arrangement for driving a single (active) individual antenna EA with, for example, three different intermediate frequency signals ZF1 to ZF3, which differ in their center frequency and which are present at the inputs P1 to P3. These intermediate frequency signals pass via associated bandpass filters BPZF 1 to BPZF 3 to first inputs of the first mixers M11 to M13. Oscillator signals OS 1 to OS 3, which are derived from the output signal of a single oscillator OSC, are now present at their second inputs (oscillator inputs). The oscillator signals OS 1 to OS 3 therefore all have the same frequency, but different phase positions, which can be set by the phase actuators PH 1 to PH 3. The amplifiers V 1 to V 3 serve, according to FIG. 2, for decoupling and amplification of the signals. The output signals of the first mixers M 11 to M 13 pass via associated bandpasses BPA 1 to BPA 3 to a coupling element KO, for example a branching arrangement consisting of several couplers. The individual antenna EA is connected to its output P4.

The circuit arrangement described thus consists of a coupling of several, here three, circuit arrangements according to FIG. 2 to a single antenna EA. If several individual antennas controlled in this way are now combined to form a group antenna mentioned at the outset, this can advantageously be operated simultaneously with three different transmitting and / or receiving lobes. These are advantageously completely independent of one another and can therefore e.g. Send and / or receive in three different directions simultaneously. In this case, it is only necessary to set the phase actuators once. Such a group antenna is e.g. can be used as a directional radio antenna, with which simultaneous transmission and / or reception can take place independently in three different fixed directions, provided the first mixers M 11 to M 13 are designed as bidirectional mixers.

If, on the other hand, these are changed as a function of time, pivoting of the three transmitting and / or receiving lobes mentioned as examples is possible, for example. With such a group antenna, which is designed as a radar antenna, it is possible, for example, to monitor a predeterminable spatial area with mutually independent antenna lobes (directional diagrams) in different frequency ranges.

It can be seen that the example according to FIG. 4 can optionally also be modified to a different number of independent mixing arrangements.

In the example according to FIG. 4 are mixed arrangements according to FIG. 2 used. Alternatively, the use of mixing arrangements according to FIG. 3 possible. In this case, especially for a radar system, due to the use of digital synthesizers DDS, very high phase resolutions, e.g. <1 °, possible as well as a highly precise so-called zeroing of the antenna diagram. This means that there are negligible side lobes at most, so that excellent interference suppression is achieved. A radar system equipped in this way can therefore be used advantageously in a very versatile manner.

The decentralized arrangement, that is to say one digital synthesizer per individual antenna, advantageously advantageously simplifies further signal processing, in particular that of the received signal. For example, the existing otherwise very complex signal processor can be replaced by a less expensive version.

The exemplary embodiments described enable an advantageous frequency conversion to a lower IF frequency position, for example 3 GHz, in particular in the case of radar systems operating at high frequencies, for example 12 GHz, in the immediate vicinity of a (single) antenna. This greatly simplifies further signal processing, for example processing of transmit and / or receive signals, because disruptive effects of possibly existing phase errors occur at most in a negligible form. In the low IF frequency position, it is advantageously possible to manufacture the signal processing system mentioned more cost-effectively, since the components and assemblies required are more cost-effective.

Such circuit arrangements can advantageously be integrated monolithically on a chip, so that spatially compact and mechanically robust structural units can be produced which work reliably and reproducibly.

FIG. 5 shows exemplary embodiments for a phase actuator PH (FIG. 2, FIG. 4) which is suitable for a frequency of 5 GHz to 6 GHz and a phase shift of 360 ° and which can also be integrated monolithically. The exemplary embodiments show switched filter structures (left part of FIG. 5) which contain field effect transistors and can therefore be used both as high-pass HP and as low-pass LP. The switching is carried out by switching voltages U₁, U₂. In the right part of FIG. 5 the associated functional principles are shown.

The invention is not limited to the exemplary embodiments described, but can be applied analogously to others.

Claims (11)

Circuit arrangement for operating a broadband phase-controlled group antenna, which consists of a plurality of broadband individual antennas, an associated antenna signal being able to be applied to each individual antenna and the antenna signals belonging to a frequency differing in neighboring individual antennas by a phase difference, characterized in that - That each individual antenna has a mixer arrangement, at least consisting of a mixer (M1), each with one end of an intermediate frequency path (P1, BPZF, M1), an oscillator path (OSC, PH, V, M1) and an antenna path (M1, BPA, P4) is connected, assigned, - That an amplitude limiter circuit is present in the mixer arrangement and - That in the oscillator path (OSC, PH, V, M1) there is a phase actuator (PH) that can be set according to the phase difference. Circuit arrangement according to Claim 1, characterized in that the phase actuator (PH) contains at least one switched filter structure. Circuit arrangement according to claim 1, characterized in that a phase actuator (PH) is present, at least consisting of - A second mixer (M2), the first input of which is connected to the oscillator (OSC) of the oscillator path and the output of which can be coupled to the oscillator input of the first mixer (M1), and - an auxiliary oscillator (DDS),
which is connected to the second input of the second mixer (M2) and whose frequency and phase position are adjustable and coupled to those as oscillators (OSC). Circuit arrangement according to claim 3, characterized in that the auxiliary oscillator (DDS) is designed as a digital synthesizer. Circuit arrangement according to one of the preceding claims, characterized in that - That there are several intermediate frequency paths; - That there is a mixing arrangement for each intermediate frequency path; - That the oscillator paths of the mixing arrangements are combined and connected to an oscillator (OSC) and - That the antenna paths of the mixing arrangements are combined via a coupling element (KO). Circuit arrangement according to one of the preceding claims, characterized in that the first mixer (M1) is designed as a bidirectional mixer. Circuit arrangement according to one of the preceding claims, characterized in that the mixing arrangement is designed as a monolithic circuit arrangement. Circuit arrangement according to one of the preceding claims, characterized in that the group antenna is designed as a radar antenna. Circuit arrangement according to one of the preceding claims, characterized in that the group antenna is designed as a directional radio antenna. Circuit arrangement according to one of the preceding claims, characterized in that the group antenna is designed for multi-frequency operation. Circuit arrangement according to one of the preceding claims, characterized in that one of the intermediate frequencies is designed for the radar range.

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