EP4024613A1 - Verfahren zum einstellen einer antenne, ausrichter und antenne - Google Patents

Verfahren zum einstellen einer antenne, ausrichter und antenne Download PDF

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Publication number
EP4024613A1
EP4024613A1 EP21212463.0A EP21212463A EP4024613A1 EP 4024613 A1 EP4024613 A1 EP 4024613A1 EP 21212463 A EP21212463 A EP 21212463A EP 4024613 A1 EP4024613 A1 EP 4024613A1
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EP
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Prior art keywords
frequency
sub
phase
phase shift
band
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EP21212463.0A
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English (en)
French (fr)
Inventor
Jaki AMAR
Alain BOUEDO
Christian Renard
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Thales SA
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Thales SA
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q3/00—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system
    • H01Q3/26—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture
    • H01Q3/267—Phased-array testing or checking devices

Definitions

  • the invention lies in the field of array antennas having several channels each comprising a radiating element. It relates, in particular, to electromagnetic antennas of the active electronic scanning antenna type used, in particular, to equip radars or seekers.
  • the field of application is that of antennas capable of operating in a narrow band mode of operation on different frequency sub-bands of restricted range, commonly called “instantaneous frequency bands", contiguous having the same width reduced in frequency and allowing a conventional operating mode of the moving target visualization or MTI (Moving target indicator) type and a so-called broadband operating mode, that is to say frequency sweeping over a wide frequency band comprising several of the frequency sub-bands, for example, for a synthetic aperture radar (SAR) or for a pulse compression radar.
  • SAR synthetic aperture radar
  • a frequency sweep is carried out over a wide band of frequencies so as to use measurements made at different frequencies of different frequency sub-bands to calculate a distance from a target and, ultimately, to form the same radar image.
  • the fact of using measurements obtained by scanning a wide band of frequencies makes it possible to increase the resolution in distance.
  • the invention relates to the calibration, that is to say the calibration, of such antennas.
  • an antenna with a wide global frequency band for example of the order of 500 MHz, operates in instantaneous frequency bands (or frequency sub-bands), for example each having a range of a few tens of MHz, for example 50 MHz.
  • a defined phase shift command is applied to each of the antenna channels so as to obtain a pointing of the antenna in a given direction, forming a given angle with a reference direction linked to the network, at a given frequency of one of the frequency sub-bands.
  • the phase shift command applied to each channel is the same regardless of the operating frequency within the frequency sub-band considered.
  • a calibration operation is performed to phase balance the N channels of the antenna array with a view to correcting the phase deviations introduced between the different channels due to differences between the N transmission or reception chains.
  • the phase shifts introduced by the different channels i are measured and stored in the computer, called the computer pointer.
  • the main calibration coefficient CALj i is the phase difference measured, for channel i, between the signal of output of channel i and the signal injected at the input of said channel, in transmission or in reception, at the central frequency Fc j of the sub-band ⁇ F j for the zero angular pointing.
  • a calibration table comprising the M sets CALj is obtained.
  • phase shift commands ⁇ ij are the phase shifts applied by respective phase shifters of the respective antenna channels V i for any operating frequency of the sub-band ⁇ F j .
  • a solution is known for pointing in a predetermined direction defined by a pointing angle ⁇ 0 , consisting in applying to the different antenna channels, for any frequency included in the wide band of frequencies to be covered, the phase shift commands determined, for this angle ⁇ 0 , at the central frequency Fcc of the wide frequency band to be covered.
  • the phase shift commands are adjusted by means of the calibration set defined for the angle ⁇ 0 , at the central frequency Fcc of the central frequency band ⁇ Fc of the wide frequency band to be covered.
  • a second solution consists in replacing the phase shifters used for the angular scanning of the radiated beam by lines of programmable length or LLP introducing time delays (phase shifts) between the different channels. The radiated beam then remains angularly fixed with the frequency.
  • the main defect of this solution consists in the size of the LLPs which depends on the size of the antenna and the maximum pointing angle of the beam.
  • Another limitation consists in the ohmic losses in this type of components.
  • An object of the present invention is to limit at least one of the aforementioned drawbacks.
  • channel insertion phase is meant a phase shift introduced by a channel, between a channel input signal and a channel output signal. This is the phase shift between the channel excitation signal and the signal radiated by the channel in transmission mode and, in reception mode, between the signal sent to the channel and the signal measured at the channel output (c' i.e. a signal generated at the channel output).
  • the signal radiated by the antenna is measured at any predetermined point in the environment and the signal transmitted to the channel is transmitted from any predetermined point in the environment.
  • the signal radiated by the antenna is measured at the same point in the environment at the different frequencies at from the same input signal, or respectively the same signal is transmitted to the channel from the same point in the environment at different frequencies.
  • the signal radiated by the respective channels is measured at identical respective relative positions with respect to the respective channels of the antenna, the antenna input signal being the same, or respectively the same signal is transmitted to the respective channels from identical respective relative positions with respect to the respective channels of the antenna and the signal at the output of the respective channels is measured.
  • the operation of phasing the different channels that is to say the operation of adjusting the phase shifts to avoid the introduction, between the different channels, of phase shifts other than those which must be introduced to point the antenna in the desired direction consists, at first order, in controlling the phase shift of each channel i by a calibration command main (- CALj i ) equal to the opposite of the main calibration coefficient CALj i (or phase shift) measured for channel i.
  • phase shift introduced by channel i does not vary with the frequency in each of the sub-bands and the opposite of the phase shift CALj i measured at the central frequency Fcj is applied so as to maintain this phase shift. constant. This amounts to imposing a zero insertion phase at each central frequency Fcj.
  • the frequencies fk are included in the three contiguous sub-bands ⁇ F x+1 , ⁇ F x +2 and ⁇ F x+3 .
  • the central frequencies Fc x+1 , Fc x+2 , Fc x+3 of the respective sub-bands ⁇ F x+1 , ⁇ F x+2 and ⁇ F x+3 have respective order numbers 80, 96, 112 respectively. There are 16 frequencies per subband in the non-limiting example of the figure 1 .
  • the phase d insertion is substantially zero.
  • the central frequency or calibration frequency is the frequency f80.
  • this calibration does not take into account the fact that the insertion phase measured by a measuring instrument is the sum of a phase shift independent of the frequency and a phase shift linked to a transit time that the signal has taken for propagate in the corresponding channel, i.e. linked to the electrical length of the channel. If it is assumed that these media are not dispersive, which is the case in practice, this so-called transit time is constant in the sense that it does not depend on the frequency. On the other hand, the transit time causes a phase shift which depends on the frequency and, more precisely, which varies linearly with the frequency.
  • the insertion phase is equal to ⁇ phi
  • the insertion phase is equal to 2* ⁇ phi
  • the phase is equal to ⁇ phi.
  • the insertion phase varies sawtooth over the first frequency band consisting of the three contiguous sub-bands Fc x+1 , Fcx+ 2 and Fc x+3 .
  • the absolute value of the phase difference DF between these two consecutive frequencies is much greater than that of ⁇ phi. There is therefore no continuity of insertion phases between the different sub-bands.
  • This discontinuity is incompatible with a broadband application, the measurements used to produce a radar image having to be frequency coherent.
  • phase difference between two consecutive frequencies is caused solely by the transit between these two frequencies.
  • the insertion phase should present the pace represented in figure 2 on which the insertion phases are located on a straight line with a slope equal to ⁇ phi/ ⁇ f where ⁇ f is the difference between two consecutive frequencies, this difference being equal to unity on the figure 1 .
  • phase shift linked to a transit time in the antenna only introduces a small bias in the distance measurement.
  • phase shifts related to the different transit time are introduced at different frequencies by a calibration defect, noise is added to the phase measurements at the different frequencies and the distance can no longer be deduced with good resolution.
  • the present invention therefore proposes to use, in the transmission and/or reception phase, an estimate of the phase shift due to the transit time between two consecutive frequencies to adjust the phase shift commands so as to avoid the introduction of a insertion phase discontinuity when passing from one sub-band to the contiguous sub-band.
  • This calibration method by re-establishing the phase continuity between the different sub-bands, allows use of the antenna in broadband mode.
  • the subject of the invention is a method for calibrating an array antenna with electronic scanning comprising a set of channels each comprising a radiating element, the array antenna being capable of operating in a set of frequency sub-bands contiguous bands forming an overall frequency band, each frequency sub-band comprising a central frequency
  • the calibration method comprising the following step: Generating phase shift commands intended to be applied to the respective channels in the operational phase in an operating mode in transmission or reception, so that the antenna points in a predetermined pointing direction at a first frequency belonging to a first sub-band of the set of sub-bands, the phase shift commands being defined, for each channel, by the difference between a theoretical insertion phase of the channel, in the operating mode, and an overall phase shift being the sum of an insertion phase tion of the channel in the mode of operation at the central frequency of the first sub-band of frequencies, and of a transit phase shift introduced by a transit time, between the central frequency of the first sub-band of frequencies and a reference center frequency, in the operating mode, when the
  • the first insertion phase is measured at a central frequency of one of the sub-bands.
  • the method comprises a step of correcting the first and second insertion phases by eliminating, before the step of estimating the global phase shifts, insertion phases introduced by a device for measuring the first insertion phase and of the second phase of insertion.
  • the invention also relates to a pointer for generating phase shift commands for the channels of an electronically scanned array antenna comprising a set of channels each comprising a radiating element, the array antenna being capable of operating in a set of sub- contiguous frequency bands forming a band of global frequencies, the pointer comprising command generation means configured to generate intended to be applied to the respective channels in the operational phase in a mode of operation in transmission or in reception, so that the antenna points in a direction pointing at a first frequency belonging to a first sub-band of the set of sub-bands, the phase shift commands being defined, for each channel, by the difference between a theoretical insertion phase of the channel, in the operating mode, and an overall phase shift being the sum of an insertion phase of the channel in the operating mode at the central frequency of the first frequency sub-band, and of a transit phase shift introduced by a time transit, between the center frequency of the first frequency sub-band and a reference center frequency, in the operating mode, when the reference center frequency ence does not belong to the first frequency sub-band
  • the pointer comprises a memory storing a calibration table defined for the mode of operation, the calibration table comprising, for each channel of the antenna, a set of global phase shifts defined for the central frequencies of the respective sub-bands, each global phase shift being the sum of an insertion phase of channel i, in the operating mode, at one of the central frequencies of the sub-bands and of a transit phase shift introduced by a transit time between the central frequency and a central reference frequency.
  • the invention also relates to an array antenna with electronic scanning comprising a set of antenna channels each comprising a radiating element, the array antenna being capable of operating in a set of contiguous frequency sub-bands of width forming a band of global frequencies, the electronically scanned array antenna comprising the pointer according to the invention, the commands generated by the pointer being intended to control phase shifters of the antenna channels.
  • the invention relates to a method of calibration, that is to say of calibrating an array antenna.
  • the radiating elements E i form an array R of radiating elements.
  • the network of radiating elements is two-dimensional or three-dimensional.
  • the radiating elements E i are regularly distributed along the straight line D. They are separated two by two by a distance d.
  • the antenna of the picture 3 is able to operate alternately in transmission and in reception.
  • the transmission/reception functions are alternated by switches C1 i , C2 i , C3 i controlled by a synchronization clock H.
  • Array Antenna A is an electronically scanned antenna.
  • a single control module MC 1 configured to control the radiating element E 1 is shown in picture 3 but in reality, each channel comprises a control module of the same architecture as the control module MC 1 .
  • control module MC i comprises a variable attenuator A i and an electronic phase shifter D i respectively making it possible to apply an attenuation and to apply a phase shift to an input signal the channel V i both in transmission and in reception , from an attenuation command and respectively, from a phase shift command.
  • phase shift commands and the attenuation commands are generated by a pointer P.
  • the phase shift commands addressed to the respective phase shifters D i are generated by a computer CP of the pointer from theoretical phase shift commands (or theoretical insertion) and global phase shift commands stored in a memory MEM of the pointer P.
  • a splitter/combiner RC having an input/output ERC supplies the control modules MC i .
  • the phase shift and attenuation are applied to the signal received at the input of the control module MC i by the phase shifter D i and, respectively, the attenuator A i , from the phase shift and attenuation commands generated by the pointer P.
  • the switches C1 i , C2 i and C3 i are controlled by the clock H, and the signal leaving the phase shifter D i is amplified by a power amplifier AP i , before exciting the radiating element E i .
  • the combiner splitter RC receives the signals which are routed by the control modules MC i from the radiating element E i .
  • the signals coming from the radiating elements E i are switched by the switches C1 i , C2 i and C3 i on the reception channel and pass through a low noise amplifier AF i .
  • the phase shift and the attenuation are applied by the phase shifter D i and the attenuator A i , controlled by the pointer P.
  • This array antenna architecture is well known to those skilled in the art but other electronically scanned antenna architectures can of course be envisaged.
  • the antenna is able to operate only in transmission or in reception.
  • phase shifters D i are controlled by the pointer P configured to generate phase shift commands from a pointing setpoint corresponding to a pointing direction.
  • phase shifters D i are controlled by the respective phase shift commands so that the phase shifters apply the respective phase shifts, corresponding to the respective phase shift commands, to the different channels V i , so that the antenna points in the pointing direction.
  • Antenna A is capable of operating alternately in different contiguous frequency sub-bands ⁇ F j , of width ⁇ F, forming an overall frequency band of width ⁇ FG.
  • the present invention relates to a method for calibrating an antenna, or method for generating phase shift commands corresponding to phase shifts intended to be applied, in the operational phase in an operating mode in transmission or in reception, by the respective channels on respective input signals of said channels, so that the antenna points in a predetermined pointing direction at a first frequency belonging to a first sub-band of the set of sub-bands in which one generates, for each channel i, a phase shift command defined by the difference between a theoretical insertion phase of channel i, in the operating mode, and an overall phase shift being the sum of a main insertion phase of channel i, in the mode of operation, at the central frequency of the first frequency sub-band, and of a transit phase shift introduced by the antenna due to a transit time between the central frequency of the first first sub-band of frequencies and a central reference frequency, in the reception mode, when the central reference frequency does not belong to the first sub-band of frequencies.
  • the reference center frequency is the same for all frequencies and all channels.
  • the global phase shift is the main insertion phase of the channel, at the central frequency of the first sub-band of frequencies being the reference center frequency, in the mode of operation.
  • the center frequency of a frequency sub-band is the frequency at the center of the frequency sub-band.
  • phase shift introduced by the transit time is defined from an estimate of the phase shift caused by the transit time between two frequencies separated by a frequency difference equal to ⁇ F .
  • This phase shift is called inter sub-band transit phase shift dphi in the rest of the text.
  • the calibration method according to the invention makes it possible to eliminate the phase jumps between the adjacent frequency sub-bands and thus to obtain phase continuity between the sub-bands, which allows the use of the antenna for broadband applications.
  • a global calibration table comprising the global phase shifts defined, in one mode of operation, for each channel of the antenna, for each frequency sub-band.
  • the calibration table comprises, for each channel of the antenna, a set of global phase shifts defined for the central frequencies of the respective sub-bands, each global phase shift being the sum of an insertion phase introduced by channel i, in the operating mode, at one of the central frequencies and of a transit phase shift induced by a transit time between the central frequency and a reference central frequency.
  • Each global phase shift used to generate the phase shift commands intended for the respective channels is taken from the global calibration table defined for the desired mode of operation (transmission or reception).
  • a calibration table in transmission and a table of reception calibration is determined in transmission or in reception.
  • the calibration method comprises, as shown in figure 4 , a step 100 of estimating the inter-subband transit phase shift.
  • phase shift In order to estimate the transit phase shift, it is necessary to measure a phase shift between two sufficiently close frequencies so that the phase shift introduced by the transit time between these two frequencies is less than 2 ⁇ . Indeed, the phase is modulo 2 ⁇ .
  • the calibration method according to the invention therefore comprises, for at least one of the radiating elements R i , a step 10 of measuring phase shifts d ⁇ ik (or insertion phases) respectively introduced by the channel i considered (when this radiating element of the channel is the only radiating element of the set R of radiating elements to operate, or alternatively, the only radiating element of the set R in electromagnetic visibility of the measurement probe S) at different measurement frequencies fk spaced two to two with a pitch such that the phase shift introduced between these two frequencies is less than 2 ⁇ .
  • the measurement frequencies belong, for example, to the same sub-band, but this is not compulsory.
  • the measurement frequencies are advantageously spaced apart by a frequency difference less than ⁇ F.
  • the phase shift measurement d ⁇ ik (or insertion phase) is, for example, carried out in the near field, that is to say, from a measurement carried out at a distance of the order of the wavelength of the radiating element E i at the frequency fk.
  • the measurement step 10 comprises, for example, for a channel i, a step of measuring the insertion phase d ⁇ ik of the signal transmitted at different measurement frequencies fk regularly spaced by a step ⁇ f in frequency.
  • Each measurement 10 is performed by the same measuring device DM.
  • the measuring device DM comprises, for example, as shown in picture 3 , a measurement probe S connected by a first cable CA 1 to a measurement bay BAI, itself connected by a second cable CA 2 , to the input/output ERC of the combiner splitter RC.
  • the BAI measurement bay comprises measurement means, for example a network analyzer, making it possible to measure, in transmission, the phase of insertion of the channel V i from the phase of the signal received by the probe S and from that the excitation signal injected into the ERC input of the RC combiner splitter and generated, for example, by a microwave signal generator of the BAI measurement rack.
  • the BAI measurement bay also includes a microwave signal generator enabling the antenna to be excited at its ERC input so that it emits a signal towards the probe.
  • the measurement bay BAI measures the insertion phase of the channel V i from a signal emitted by a microwave signal generator of the bay BAI and radiated by the probe S and from a signal delivered at the output ERC of the combiner splitter and measured by a BAI array network analyzer.
  • the BAI measurement bay advantageously comprises a positioner making it possible to move the probe relative to the antenna and to position the probe relative to the array of radiating elements in respective predetermined relative positions relative to the array R of radiating elements so that the insertion phase measurements carried out for each channel in the operating mode are carried out in a predetermined relative position between the radiating element of the channel and the probe, this relative position being the same for all the channels.
  • the positioner is configured to make it possible to move the probe by a pitch equal to d along the line D and to keep it in position with respect to the network R in each of the positions spaced apart by the pitch d.
  • the probe is positioned in the field close to the radiating element of the channel for which the measurement is carried out.
  • the method advantageously comprises a step 20 of correcting each phase shift d ⁇ ik, or insertion phase, by subtracting, from the phase shift d ⁇ ik, a phase shift d ⁇ ck introduced by the measuring device DM at the measurement frequency at which the phase shift is measured d ⁇ ik.
  • the measuring device DM introduces phase shifts related to the transit time of the electrical signals, in particular in the cables CA 1 and CA 2 and in the measurement bay BAI.
  • the phase shifts introduced by the measuring device DM due to the electrical length of the measuring device are different depending on the frequency of the signal and therefore alter the continuity between the frequency sub-bands.
  • the method advantageously comprises a step 15 of prior measurement of the phase shifts d ⁇ ck introduced by the measuring device DM at the frequencies fk.
  • the measuring device DM uses these measurements to calculate the number of measurements to calculate the number of measurements.
  • the radiating element E0 is within of a passive array of charged radiating elements, representing the surrounding radiating element.
  • the method then comprises a step of estimating the average unit transit phase shift ⁇ phi introduced by the antenna, due to the transit time in channel i between two measurement frequencies separated by the pitch ⁇ f.
  • one calculates, for example, during a step 30, from the corrected phase shifts dc ⁇ ik obtained, the average unit transit phase shift ⁇ phi between two transit phase shifts obtained for respective measurement frequencies spaced apart by ⁇ f.
  • This mean unit transit phase shift ⁇ phi is an estimate of a phase difference introduced, under the effect of the transit time, by channel i, between two frequencies spaced apart by ⁇ f.
  • the inter-subband transit phase shift dphi is estimated from average unit transit phase shifts estimated for different channels i.
  • the method then comprises steps of estimating the average unit transit phase shifts for these different channels and a step of calculating an average unit transit phase shift from the average unit transit phase shifts determined for several channels i.
  • the average unit phase shift is estimated from phase shifts measured for a smaller number of measurement frequencies spaced apart by ⁇ f for one or more channels.
  • the average derivative of the unit phase shift is estimated from the estimated phase shifts and the inter-subband transit phase shift is estimated from this derivative.
  • the method then comprises a step 50 of storing the estimated transit phase shift dphi in a memory, for example, a memory of the measurement bay BAI.
  • the calibration method according to the invention also comprises a step 200 of determining a so-called main calibration table comprising M sets of main phase shifts CCALj, where M is the number of central frequencies at which the main phase shifts are determined on the frequency band overall.
  • the main phase shift CCALj i is the phase shift introduced by channel i at the central frequency Fcj of the sub-band ⁇ F j on an input signal of channel i in the operating mode. This is the insertion phase of channel i.
  • Step 200 is carried out as described above with reference to steps 10 to 20, the main phase shift CCALj i being the phase shift introduced by a channel i at a particular frequency fk corresponding to the central frequency Fcj of the band ⁇ F j .
  • the step 200 comprises, for each channel i, a step 210 of measuring phase shifts d ⁇ ij respectively introduced by the considered channel i (when this radiating element of the channel is the only radiating element of the set R of elements elements to operate, or alternatively, the only radiating element of the assembly R in electromagnetic visibility of the measurement probe S), at the various central frequencies Fcj belonging to the frequency sub-bands ⁇ F j .
  • Step 210 is, for example, performed by the measuring device DM.
  • phase shifts introduced by the various channels are measured with respect to the same reference signal for all the channels in the mode of operation considered.
  • the method advantageously comprises a step 220 of correcting each phase shift d ⁇ ij by subtracting, from the phase shift d ⁇ ij, the phase shift d ⁇ cj introduced by the measuring device DM at the frequency Fcj.
  • the method advantageously comprises a step 215 of prior measurement of the phase shifts d ⁇ cj introduced by the measuring device DM at the frequency Fcj as described previously with reference to step 15.
  • the method comprises, for each channel i, the determination 60 of an overall phase shift NCALj i for each central frequency Fcj.
  • This overall phase shift is determined from the main phase shift CCALji determined for the channel considered at the central frequency Fcj and from the transit phase shift dphi.
  • the overall phase shift is the sum of the main phase shift (main insertion phase) and the transit phase shift induced by the transit time between the central frequency Fcj and a central reference frequency Fcr, i.e. the frequency central reference Fcr at the central frequency Fcj.
  • NCALj i CCAL 1 I
  • NCAL 2 I CCAL 2 I + dphi
  • NCAL 3 I CCAL 3 I + 2 * dphi ... .
  • NCALj I CCALj I + I ⁇ 1 * dphi
  • NCALM I CCALM I + M ⁇ 1 * dphi
  • the global phase shifts NCALj i are then used to adjust the phase commands applied to the channels i so that the antenna points in a predefined pointing direction at a frequency fk belonging to one of the sub-bands ⁇ Fcj so as to substantially compensate for the phase shifts introduced between the different channels i by the elements making up the different channels, at the central frequency Fcj of the sub-band ⁇ Fcj and so that a phase shift introduced by a transit time between the central frequency Fcj of the sub-band ⁇ Fcj and a central reference frequency varies linearly with the central frequency Fcj.
  • the global phase shifts NCALj i are used to correct the theoretical phase commands which are the theoretical insertion phases that must actually be introduced by the respective respective channels V i to point the antenna according to a predetermined pointing direction at the frequency fk of the ⁇ Fcj sub-band.
  • the theoretical phase commands are the phase commands to be applied to the respective channels to point the antenna along a pointing direction at the frequency fk in the absence of phase shifts introduced, between the different channels, by the components of the different channels, at the central frequency Fcj of the sub-band ⁇ Fcj, and phase shifts related to the transit time between the central frequency Fcj and a central reference frequency Fcr.
  • the calibration method according to the invention makes it possible to fix the phase difference between two consecutive frequencies fk to fk+1 to ⁇ phi within the same sub-band but also at the passage of a sub-band ⁇ Fj to the next sub-band ⁇ Fj+1.
  • the method comprises a step 80 of determining phase shift commands, in order to point the antenna in a given direction at the frequency fk belonging to a sub-band ⁇ F j , forming a predetermined pointing angle with respect to a direction linked to the network of radiating elements.
  • This step 80 includes, for each channel i, a step of calculating a difference between the theoretical command and the associated global phase shift.
  • the theoretical phase commands can be stored, beforehand, in a memory or calculated in operation by the computer of the pointer by means of an equation stored in a memory then optionally stored in a memory of the pointer.
  • ⁇ t ij is the theoretical phase shift command to be applied at the central frequency Fcj to channel i for angular pointing.
  • the method then comprises a step of applying the phase shifts to the various channels comprising a step 90 of transmitting the phase shift commands ⁇ ij to the phase shifters and a step 91 of applying the corresponding phase shifts by the phase shifters.
  • the figure 7 and 8 illustrate measurements made in the far field on the radiation pattern of an array antenna whose array of radiating elements is two-dimensional, comprising several hundred channels.
  • These figures represent the deviations of the phase of the main lobe between frequencies fk spaced by ⁇ f, measured in an antenna measurement base, on the one hand for a beam pointed in the direction 0° ( figure 7 ), on the other hand for a beam offset by 60° in the circular plane ( figure 8 ).
  • Each main lobe is obtained by the radiation of the set of radiating elements excited by excitation signals whose phase shifts are adjusted by means of the overall phase shifts.
  • the global phase shifts NCALj i are generated during a so-called prior calibration step, prior to the use of the antenna in operational mode.
  • the measurements of the insertion phases can be carried out in the near field as explained previously. As a variant, these measurements are carried out in the far field.
  • the invention also relates to a broadband method for estimating a distance between the antenna and a point at the origin of an echo comprising a step of generating phase shift commands in transmission so that the antenna transmits microwave signals at several emission frequencies included in several emission frequency sub-bands, a step of generating phase shift commands in reception so that the antenna delivers measurements of signals received at several reception frequencies included in several reception frequency sub-bands under the effect of the emission of the microwave signals, and a processing step consisting in estimating a distance, separating the antenna from a point at the origin of an echo (for example , a target or part of a target), from the measurements of the signals received by the antenna, during a reception step and, advantageously, constructing an image representing echo intensities as a function of the distance separating t the antenna of points at the origin of the echoes.
  • a broadband method for estimating a distance between the antenna and a point at the origin of an echo comprising a step of generating phase shift commands in transmission so that the antenna transmits microwave signals at several emission frequencies
  • the method also advantageously comprises the steps of transmission and reception via the antenna channels.
  • phase shift commands intended for the phase shifters of the different channels in the different sub-bands, during the transmission and reception phases are generated by the calibration method according to the invention.
  • the invention also relates to the pointer P comprising a pointer calculator CP comprising a command generator able to generate the phase shift commands from the calibration table and from theoretical insertion phases.
  • the invention also relates to a pointer P, the command generator of which is configured to implement the steps for generating phase shift commands, during a method for estimating a broadband type distance, so that the antenna comprising the pointer implements the transmission and reception steps of this method, and comprising an estimator EST configured to estimate the distance from the measurements delivered during the reception phase.
  • the invention relates to an antenna configured to implement the distance estimation method according to the invention.
  • the distance estimation can be based on linear frequency modulation or on a multicarrier code.
  • An advantage of the invention lies in the fact that the global phase shifts can also be used in a narrow band operating mode to control the phase shifters so as to transmit or receive electromagnetic waves from one or more frequencies belonging to the same sub-band and to use measurements of signals received only in the sub-band to construct an image.
  • the transit phase shifts added to the respective main phase shifts to generate the global command are the same for all the channels in a considered sub-band. They therefore do not affect the radiation pattern of the antenna.
  • a calibration table is stored per mode of operation.
  • the calibration table includes the global phase shifts.
  • the calibration table includes the main phase shifts and the inter-subband transit phase shift or its derivative is stored and the global phase shifts are calculated from the main phase shifts and the transit phase shift or its derivative.
  • Each computer may include one or more dedicated electronic circuits or a general purpose circuit.
  • Each electronic circuit can include a reprogrammable calculation machine (a processor or a microcontroller for example) and/or a computer executing a program comprising a sequence of instructions and/or a dedicated calculation machine (for example a set of logic gates such as an FPGA, DSP or ASIC, or any other hardware module).

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EP21212463.0A 2020-12-30 2021-12-06 Verfahren zum einstellen einer antenne, ausrichter und antenne Pending EP4024613A1 (de)

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FR2014262A FR3118539B1 (fr) 2020-12-30 2020-12-30 Procede de calibration d'une antenne, pointeur et antenne

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EP4024613A1 true EP4024613A1 (de) 2022-07-06

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017060170A1 (fr) * 2015-10-07 2017-04-13 Thales Procédé de calibrage d'une antenne à balayage électronique sectorisée, et dispositif de mesure correspondante
US9923269B1 (en) * 2015-06-30 2018-03-20 Rockwell Collins, Inc. Phase position verification system and method for an array antenna
US10615495B1 (en) * 2017-09-25 2020-04-07 National Technology & Engineering Solutions Of Sandia, Llc Ultra-wideband mutual coupling compensation of active electronically scanned arrays in multi-channel radar systems

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9923269B1 (en) * 2015-06-30 2018-03-20 Rockwell Collins, Inc. Phase position verification system and method for an array antenna
WO2017060170A1 (fr) * 2015-10-07 2017-04-13 Thales Procédé de calibrage d'une antenne à balayage électronique sectorisée, et dispositif de mesure correspondante
US10615495B1 (en) * 2017-09-25 2020-04-07 National Technology & Engineering Solutions Of Sandia, Llc Ultra-wideband mutual coupling compensation of active electronically scanned arrays in multi-channel radar systems

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
FENG FAN ET AL: "Internal Calibration and Range Replica Extraction Scheme for Ultra-high Resolution Spaceborne SAR", 2019 6TH ASIA-PACIFIC CONFERENCE ON SYNTHETIC APERTURE RADAR (APSAR), IEEE, 26 November 2019 (2019-11-26), pages 1 - 4, XP033751365, DOI: 10.1109/APSAR46974.2019.9048533 *

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FR3118539B1 (fr) 2022-12-16

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