FR2751136A1 - MIXED HYPERFREQUENCY PHASE DEVICE AND ITS APPLICATION - Google Patents

Abstract

The microwave phase shifter device comprises, in series, two diode phase shifters (DD1, DD2), operating respectively on 180 and 90 deg., And followed by a ferrite phase shifter (DF). They are associated with respective control circuits (CD, CF), subject to general digital control (CG), suitable for subdividing 360 deg. in phase increments of determined resolution. The reproducibility is improved by the fact that the control of the ferrite phase shifter (DF) is effected from calibration values, which can be obtained by adjusting, in a calibration state, the values obtained on the phase shifter. of ferrite (DF) from values available using the other two phase shifters (DD1, DD2).

Description

Mixed microwave phase shifting device and its application

cation.

  The invention relates to hyper-phase shifting devices.

  frequency. In this field, we know, among other things, the so-called "ferrite" phase shifters, as well as the so-called "diode" phase shifters. Ferrite phase shifters, which can be made reciprocal, have low losses and low cost. They are capable of a short response time, even at a high rate of repetition. Under specific conditions, the excitation power required to obtain a variation equal to one phase revolution is a few watts. Finally, analog in nature, these ferrite phase shifters are capable of being controlled by steps, that is to say by phase increments with excellent resolution. However, as they are sensitive to many parameters, including the ambient conditions, the reproducibility of the increments

  phase is quite tricky to obtain.

  For their part, diode phase shifters provide natural-

  also a possibility of quantification. But we feel

  a loss due to the diodes, taking into account the stage of communication

  tation which controls them, which goes from 0.4 to 1 db per stage,

  i.e. by desired switching step. Their consumption

  tion can go down to 50 milliwatts per floor. Their commu-

  tion is also very fast, since we can go down to response times of a few hundred nanose- condes. Being naturally quantified, the phase shifters

  diodes pose few reproducibility problems.

  On the other hand, obtaining a high resolution is difficult, given the rapid increase in losses.

  with the number of stages or no switching required.

  It turns out that we do not have a truly satisfactory solution for the manufacture of microwave phase shifting devices which are both

  high resolution and high reproducibility.

  The present invention solves this problem.

  To this end, the invention starts from a microwave phase-shifting device which is of the type comprising phase-shifters proper, capable of operating by phase step, means for direct control of these phase-shifters, and means20 for general digital control of the steps. desired phase shift. It will be noted at this level that the direct control means, which can also be called "drivers", and the aforementioned general control means interpenetrate in practice, as is known to those skilled in the art. According to a general characteristic of the invention, at least the most significant phase step is provided by a diode phase shifter, while the residual phase steps are provided by a ferrite phase shifter. The direct control means thereof are arranged to control it as a function of calibration data and

its instant condition.

  Preferably, the two higher weight phase steps

  are made by diode phase shifters.

  In a basic embodiment of the invention, the calibration data are preen recorded, in particular in non-volatile memory 3, or in read-only memory. It can be done

  from a calibration of the ferrite phase shifter during manufacturing, under different ambient conditions.

  The sensors for these ambient conditions are then installed on the ferrite phase shifter. A microprocessor can, in operation, define the control of the phase shifter at

  ferrite according to its instantaneous condition, and the prerecorded calibration data.

  However, it is currently considered preferable for the phase shifter to have a calibration state, and an operational state.

  roof, which alternate. During the calibration state, the control means align the phase shift obtained by the ferrite phase shifter with at least one reference value15 defined by the diode phase shifter or one of these.

  In practice, the phase shift alignment is performed on

  the values 90, 1800, 2700 and 360, which can be established by two diode phase-shifters of 90 and 180, in connection with the ferrite phase-shifter.

  To this end, and in a particular embodiment, the device comprises a phase measurement channel, coupled upstream and downstream of the chain of phase shifters. 25 This phase measurement channel can contain a phase shifter

  auxiliary, notably to compensate for line lengths.

  The phase measurement channel also contains a phasemeter, the output of which can be sine / cosine, or directly

phase.

  According to another aspect of the invention, the interpolation / extra-

  polation from reference values is performed on the basis of a linear approximation or an approximation

mation by cubic.

  4 Finally, the invention is particularly applicable to the construction of

  tion of the phase shifters that a network antenna comprises.

  Other characteristics and advantages of the invention

  will appear on examining the detailed description below, and the attached drawings, in which:

  - Figure 1 illustrates a particular embodiment of a microwave phase shifter device according to the invention; and

  - Figure 2 illustrates an alternative embodiment of the invention.

  In FIG. 1, a microwave signal included in a predetermined bandwidth can propagate between an input E and an output S. Those skilled in the art will understand that the representation of the path of this signal by a line is schematic, since '' it is actually a guided wave.20 From input E, the signal first meets a first DD1 diode phase shifter, then a second DD2 diode phase shifter, and finally a ferrite phase shifter DF, before reaching output S. In a known manner, the diode phase shifter DD1 comprises in parallel a direct path DD11 having a transit time to which a phase shift value REF1 can be associated, and a path DD12 arranged to provide a phase shift30 equal to REF1 + 180. Diode switches DD13 and DD14, operated in synchronism, allow selection

  one or the other of the channels DD11 and DD12.

  The DD2 phase shifter has a similar structure, with

  the difference that its channel DD22 has a phase shift greater than 90 to the phase shift REF2 of the direct channel DD21.

  For its part, the DF ferrite phase shifter can be of known structure, preferably in microstrip technology (microstrip). It is particularly advantageous to use phase shifters having a ferrite plate mounted on a ground plane, and surmounted by a dielectric support

  on which the control microstrip strips are installed.

  Such a phase shifter is described in more detail in the thesis of M. BOLIOLI, thesis of Doctor Engineer 98-1984, ENSAE, September 27, 1984, entitled "Reciprocal phase shifter in composite microstrip, ferritedielectric structure,

in centimeter waves ".

  As for the diode phase shifters, these can be produced in the manner described in SKOLNIK, Radar Handbook, 1970,

p. 12-45 and following.

  A CD circuit controls the phase shifters with diodes

  DD1 and DD2; a CF circuit controls the DF ferrite phase shifter. The two circuits CD and CF, which act as drivers, are under the control of a general digital command20 CG, which has the essential function of establishing in digital form a subdivision of a phase

  global sage of 360, which is also called "phase turn".

  The control of the diode phase shifters can be established very simply, since these intrinsically provide a quantization, respectively at 180 for the

  DD1 phase shifter and 90 for the DD2 phase shifter.

  On the other hand, the DF ferrite phase shifter is analog. We know that such a phase shifter has an area in which its response is monotonous. It is then possible to subdivide

  this zone in steps, which the CF control circuit does here.

  The known drawback of ferrite phase shifters is the lack

  of reproducibility which they present as for the resolution, compared to their full scale.

  This lack of resolution can be compensated according to the invention.

  6 tion, first of all by the fact that the full scale of the

  DF ferrite phase shifter is reduced, since the higher weights are achieved by the DD1 and DD2 diode phase shifters.

  It is then possible to store either in the circuit

  CF command, either in the CG circuit, of standard data

  prerecorded swimming, preferably in non-volatile memory or better in read-only memory. These calibration data are established for the DF phase shifter precisely used, during its manufacture, and under different ambient conditions, in particular temperature. By incorporating a temperature sensor and other relevant ambient conditions into the DF phase shifter, it is then possible to establish its control as a function of these conditions and of the exact desired phase shift value, relative

  to a series of calibration data contained in the memory.

  The preferred embodiments described here operate differently.

  On the input E is mounted a directional microwave coupler CH1. The signal taken by the latter is applied to an auxiliary phase shifter of 180, denoted DDA, and followed by a phase measurement device MP. The other input of this phase measurement device is connected to another directional coupler CH2 connected to the output S. The phase measurement device MP can be of any known type, providing the output information either under

  form of sine and cosine, either directly in the form of phase. The device described in SKOLNIK, op. cit, p. 5- 39 and following.

  The phase shifting device according to the invention is then provided, for example at the level of a logic unit incorporated in these control devices, with two different states, the first being a calibration state, and the second an effective operating state in phase shifter, or operational state. These two states are in principle alternated,

if necessary periodically.

  Note being made immediately that the invention applies to a network antenna, it is known that the operation of such antennas is not permanent, which leaves the

  make way for calibration phases between the operating phases.

  During the calibration state, the following measurements can be made, for which a reference signal is applied to the input E, while the phasemeter MP makes it possible to detect, around zero, the phase difference

enter exit.

  We note edl and ed2 the phase shift errors presented by

  the phase shifters DD1 and DD2, between their two channels.

  a) DD1 is placed on REF1. DD2 is placed on REF2. DF is set to the desired value zero (start of range

  linearity). The measurement of the phasemeter MR is phiO.

  DD2 is now placed on REF2 + 90 + ed2. Measurement

  of MP is denoted phi90 with phi90 = 90 + phiO + ed2.

  DD2 is replaced on REF2. We determine the order

  C90 of DF for which MP gives back phi90.

  b) DD2 remains on REF2. DF is set to zero. DD1 is placed on REF1 + 180 + edl. We measure a phase shift on MP

noted phil80 = 180 + phiO + edl.

  We replace DD1 on REF1. We place DD2 on REF2 + 90 + ed2. We set DF to get MP output

  phil80 value. The DF command is noted C180.

  c) DD1 is placed on REF1 + 180 + edl. DD2 is placed on REF2 + 90 + ed2. DF is set by the command value C180. MP then measures a "zero error" equal to

  twice edl, which is now known.

  d) DD2 is placed on REF2 + 90 + ed2. DD1 is placed on

REF1. DF receives the C90 command.

  MP measures phi0 + 180 + 2.ed2 = phix.

  phix - phi 180 then gives 2.ed2 - 2edl from which we draw

ed2.

  The errors of the diode phase shifters are then known.

  I1 remains to refine the adjustment of the DF ferrite phase shifter.

  e) The comparison of the values C180 and C90 (whose deviation represents edl 2.ed2) makes it possible to determine the slope of the response curve of the ferrite phase shifter, and consequently the command which gives exactly 90, using d '' an interpolation either linear or by

cubic.

  In service, we thus obtain any phase shift value

  desired up to 90, using the only DF ferrite phase shifter.

  Of course, when DD2 and / or DD1 are put into service, the DF command is shifted, according to the equivalent of ed2

and / or edl, respectively.

  Of course, the present invention is not limited to the embodiments described, and it is possible in particular to modify the structure of the auxiliary channel defined between the couplers CH1 and CH2, for example by using a different phasemeter, and / or by removing

  the DDA phase shifter, or by modifying its value.

  In the device described above, with reference to FIG. 1, the calibration takes place for part of the time

  resignation. I1 results in an emission of unfocused energy

  In some cases, this is undesirable. It is

  then preferable to use the variant of FIG. 2.

  The output S of the phase shifting device can be connected to the aerial A or to the phasemeter MP by a CES switch. The input E can be connected either directly to the generator G (operating phase), or to one of the outputs of an amplitude divider by two, denoted DV, in the calibration phase. In this case, the other output of the DV divider

  is connected to the phasemeter assembly (DDA and PM).

  This is achieved by a CEE input switch, controlled like CES, and which, during the calibration phase, connects the input of the DV divider to the generator G. In the calibration phase, it is then possible to carry out the aforementioned calibration with a reduced generator power (typically 10 mW instead of 10 watts), and this without disturbing the operation of the radar by the emission

of unfocused energy.

  Even better, we can then use the assembly of figure 1 (in addition to figure 2), to control the phase

  of the microwave energy emitted.

  Of course, the emission and the reception being reciprocal, the phase shifter according to the invention is used as well during

the capture of radar echoes.

Claims (12)

Claims.   1.- Microwave phase shifting device, of the type comprising phase shifters proper, suitable for operating by phase step (DD, DF), means for direct control of these phase shifters (CD, CE) and general digital control means (CG ) desired phase shift steps, characterized in that at least the most significant phase step (DD1) is provided by a diode phase shifter, while the residual phase steps are provided by a ferrite phase shifter (DF ), and in that the direct control means (CF) of the ferrite phase shifter (DF) are arranged to control the latter according to calibration data and its instant condition.   2.- Device according to claim 1, characterized in that the two phase steps of higher weight are   made by diode phase shifters (DD1, DD2).   3.- Device according to claim 1 or 2, characterized in that the calibration data are prerecorded,   in particular in non-volatile memory or in read-only memory.   4.- Device according to claim 1 or 2, characterized in that the phase shifter has a calibration state and   an operational state, and in that, during the standard state-   swimming, the control means align the phase shift of the ferrite phase shifter (DF) with at least one reference value   frequency defined by a diode phase shifter (DD1, DD2).   5.- Device according to claim 4, taken in combination   naison with claim 2, characterized in that the phase shift alignment is effected on the values 90, 1800, 270 and 360 which allow to establish two diode phase shifters of 90 (DD2) and 180 (DD1), in connection with the ferrite phase shifter (DF).   6.- Device according to one of claims 4 and 5,   characterized in that it includes a phase measurement channel (DDA, MP) coupled upstream and downstream of the chain phase shifters (DD1, DD2, DF).   7.- Device according to claim 6, characterized in that the phase measurement channel contains a phase shifter auxiliary of 180.   8.- Device according to one of claims 6 and 7,   characterized in that the phase measurement channel contains a phasemeter (MP) with sine / cosine output or with output phase.   9.- Device according to one of claims 6 to 8, charac-   terized in that the phase measurement channel is connected   by couplers at the two extreme terminals of the phase shifter.   10.- Device according to one of claims 6 to 9,   characterized in that the phase measurement channel is connected by switches to the two extreme terminals of the phase shifter,   with two-way input, preferably at reduced power.   11.- Device according to one of claims 4 to 10,   characterized in that the interpolation / extrapolation from the reference values is carried out on the basis of a linear approximation or an approximation by cubic.   12.- Application of the devices according to one of the claims   previous cations to a network antenna.