EP-4738731-A1 - TEMPERATURE DRIFT COMPENSATION FOR LOCAL OSCILLATORS IN PHASED ARRAY ANTENNAS

Abstract

A phased array antenna system may include a measurement network. A phased array antenna system may include a first digital beamformer (DBF) coupled to the measurement network and configured to transmit a first radio frequency (RF) calibration signal onto the measurement network. A phased array antenna system may include a second DBF coupled to the measurement network and configured to receive a first RF signal, derived from the first RF calibration signal, from the measurement network, the second DBF comprising a processor configured to: compute, based on the first RF signal, a phase difference between the first RF signal and a second RF signal; and compute a phase compensation to be applied by at least one of the first DBF or the second DBF based on the phase difference.

Inventors

• PEPIN, ERIC
• PARTRIDGE, DAVID
• SMITH, Hui

Assignees

• Space Exploration Technologies Corp.

Dates

Publication Date

20260506

Application Date

20251031

Claims (19)

1. A digital beamformer (DBF) comprising: a first radio frequency input/output (RFIO) channel electrically coupled to a measurement network and configured to receive a first radio frequency (RF) signal over the measurement network; and a processor configured to: compute, based on the first RF signal, a phase difference between the first RF signal and a second RF signal; and apply a phase compensation based on the phase difference to a third signal to be transmitted or received.
2. The DBF of claim 1, wherein the processor is further configured, in applying the phase compensation, to control a digital phase shifter to apply the phase compensation to the third signal at baseband.
3. The DBF of claim 1 or claim 2 further comprising an analog phase shifter configured to apply the phase compensation to the third signal.
4. The DBF of any one of claims 1 to 3, wherein the processor is further configured, in applying the phase compensation, to communicate the phase compensation to an analog phase shifter for application to the third signal transmitted by or to be received by the DBF.
5. The DBF of any one of claims 1 to 4 further comprising a second RFIO channel electrically coupled to the measurement network and configured to transmit a first RF calibration signal, from which the first RF signal is derived, onto the measurement network.
6. The DBF of claim 5, wherein the processor is further configured to: receive phase information for the second RF signal from a second DBF that received the second RF signal, derived from the first RF calibration signal; and compute the phase difference based on the first RF signal and the phase information for the second RF signal.
7. The DBF of claim 6, wherein the processor, in applying the phase compensation, is further configured to communicate the phase compensation to the second DBF for application to RF signals transmitted or received by the second DBF.
8. The DBF of any one of claims 5 to 7, wherein the first RFIO channel is further configured to receive the second RF signal derived from a second RF calibration signal transmitted by a second DBF coupled to the measurement network.
9. The DBF of claim 8, wherein the processor, in applying the phase compensation, is further configured to communicate the phase compensation to the second DBF for application to RF signals transmitted or received by the second DBF.
10. The DBF of any one of claims 1 to 9, wherein the first RFIO channel is further electrically coupled to a distribution network for RF signals (i) to be transmitted by the first RFIO channel for transmission over the air by at least one antenna element, and (ii) to be received over the air by the at least one antenna element and routed to the first RFIO channel.
11. A phased array antenna system including the DBF of any of claims 1 to 10 as a second DBF, the phased array antenna system further comprising: the measurement network; and a first DBF coupled to the measurement network and configured to transmit the first RF calibration signal onto the measurement network.
12. The phased array antenna system of claim 11, wherein the measurement network comprises: a first coupler configured to receive the first RF calibration signal transmitted by the first DBF and propagate the first RF signal into an RF input/output (RFIO) channel of the second DBF.
13. The phased array antenna system of claim 11 or claim 12, wherein a first local oscillator (LO) generation circuit or a first LO distribution circuit of the first DBF and a second LO generation circuit or a second LO distribution circuit of the second DBF exhibit different phase coefficients versus temperature with respect to each other.
14. The phased array antenna system of claim 13, wherein the first DBF is further configured to up-convert a first coded calibration signal to the first RF calibration signal based on a first local oscillator (LO) signal; wherein the second DBF is further configured to down-convert the first RF signal based on a second LO signal; and wherein the first LO generation circuit or the first LO distribution circuit for the first LO signal is asymmetric with respect to the second LO generation circuit or the second LO distribution circuit for the second LO signal.
15. The phased array antenna system of claim 14, wherein the second DBF is further configured to: up-convert a second coded calibration signal to a second RF calibration signal based on the second LO signal; transmit the second RF calibration signal onto the measurement network; receive the second RF signal, derived from the second RF calibration signal, from the measurement network; and down-convert the second RF signal based on the second LO signal.
16. The phased array antenna system of any one of claims 11 to 15, wherein the phased array antenna system further comprises: a third DBF coupled to the measurement network and configured to transmit a fourth RF calibration signal on the measurement network; wherein the second DBF is further configured to: transmit a second RF calibration signal and a third RF calibration signal onto the measurement network; and receive the second RF signal, derived from the second RF calibration signal, a third RF signal, derived from the third RF calibration signal, and a fourth RF signal, derived form the fourth RF calibration signal, from the measurement network; and wherein the processor of the second DBF is further configured to: compute a phase difference between the third RF signal and a fourth RF signal; and compute a phase compensation to be applied by at least one of the second DBF or the third DBF based on the phase difference.
17. The phased array antenna system of claim 16, wherein a first local oscillator (LO) generation circuit or a first LO distribution circuit of the first DBF, a second LO generation circuit or a second LO distribution circuit of the second DBF, and a third LO generation circuit or a third LO distribution circuit of the third DBF exhibit different phase coefficients versus temperature with respect to each other.
18. A method of compensating for phase drift in the phased array antenna system of any of claims 11 to 17, the method comprising: transmitting, from the first DBF, the first RF signal to the measurement network; transmitting, from the second DBF, the second RF signal to the measurement network; obtaining, by the measurement network, a first sample of the first RF signal and a second sample of the second RF signal; receiving the first sample and the second sample at the first DBF; computing the phase difference between the first RF signal and the second RF signal; and applying the phase compensation, based on the phase difference, by at least one of the first DBF or the second DBF.
19. The method of claim 18, wherein applying the phase compensation comprises: encoding, within the first DBF and the second DBF, the phase compensation into digital beam signals to be upconverted to RF and transmitted by the first DBF and the second DBF; and decoding, by the first DBF and the second DBF, phase of beams received over the air by the phased array antenna system employing the phase compensation.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 63/715,434 titled Temperature Drift Compensation for Local Oscillators in Phased Array Antennas, filed on November 1, 2024. TECHNICAL FIELD The present disclosure pertains to phased array antennas for satellite communication systems and, more particularly, systems and methods for temperature drift compensation for local oscillators in phased array antennas. BACKGROUND An antenna (such as a dipole antenna) typically generates radiation in a pattern that has a preferred direction. For example, the generated radiation pattern is stronger in some directions, i.e., the main lobes, and weaker in other directions, i.e., the side lobes. Likewise, when receiving electromagnetic signals, the antenna has the same preferred direction. Signal quality (e.g., signal to noise ratio or SNR), whether in transmitting or receiving scenarios, can be improved by aligning the preferred direction of the antenna with a direction of the target or source of the signal. However, it is often impractical or inefficient to physically reorient the antenna with respect to the target or source of the signal, i.e., to mechanically scan. Additionally, the exact location of the source/target may not be known. To overcome some of the above shortcomings of a mechanically scanned antenna, a phased array antenna can be composed of an array of antenna elements, each having an electronically controlled phase and amplitude. An advantage of a phased array antenna is its ability to transmit and/or receive signals in a preferred direction (e.g., the antenna's beamforming ability) by adjusting each antenna element's phase shift and amplitude to direct the resulting wavefront, that is, without mechanically repositioning or reorientating the array. It would be advantageous to configure phased array antennas and associated circuitry having improved accuracy, stable performance over temperature, reduced weight, reduced size, lower manufacturing cost, and/or lower power requirements. Accordingly, embodiments of the present disclosure are directed to these and other improvements in phased array antennas or portions thereof. SUMMARY In some examples, systems and techniques are described for compensating for temperature dependent phase drift in phased array antenna systems having multiple digital beamformers. In some aspects, the techniques described herein relate to a phased array antenna system including: a measurement network; a first digital beamformer (DBF) coupled to the measurement network and configured to transmit a first radio frequency (RF) calibration signal onto the measurement network; and a second DBF coupled to the measurement network and configured to receive a first RF signal, derived from the first RF calibration signal, from the measurement network, the second DBF including a processor configured to: compute, based on the first RF signal, a phase difference between the first RF signal and a second RF signal; and compute a phase compensation to be applied by at least one of the first DBF or the second DBF based on the phase difference. In some aspects, the techniques described herein relate to a digital beamformer (DBF) including: a first radio frequency input/output (RFIO) channel electrically coupled to a measurement network and configured to receive a first radio frequency (RF) signal over the measurement network; and a processor configured to: compute, based on the first RF signal, a phase difference between the first RF signal and a second RF signal; and apply a phase compensation based on the phase difference to a third signal to be transmitted or received. In some aspects, the techniques described herein relate to a method of compensating for phase drift in a phased array antenna system, the method including: transmitting, from a first digital beamformer (DBF) of the phased array antenna system, a first RF signal to a measurement network; In some aspects, the techniques described herein relate to a phased array antenna system including: a measurement network; a first digital beamformer (DBF) coupled to the measurement network and configured to transmit a first radio frequency (RF) calibration signal onto the measurement network; and a second DBF coupled to the measurement network and configured to receive a first RF signal, derived from the first RF calibration signal, from the measurement network, the second DBF including a processor configured to: compute, based on the first RF signal, a phase difference between the first RF signal and a second RF signal; and compute a phase compensation to be applied by at least one of the first DBF or the second DBF based on the phase difference. In some aspects, the techniques described herein relate to a digital beamformer (DBF) including: a first radio frequency input/output (RFIO) channel electrically coupled to a measurement network and configured to receive a first radio frequenc