Broadband radio frequency imaging surface

Patent metadata

Field	Value
Publication number	US-12287399-B2
Application number	US-202418788577-A
Country	US
Kind code	B2
Filing date	Jul 30, 2024
Priority date	Aug 5, 2022
Publication date	Apr 29, 2025
Grant date	Apr 29, 2025

Abstract

A broadband RF imaging device includes a broadband RF aperture array, at least one RF receiver, and a computer. The at least one RF receiver has short RF connections with the broadband RF aperture array, e.g. length 10 meters or less. The computer has a digital data connection to the at least one RF receiver. Each RF receiver is configured to receive broadband RF signal data over a sampling time interval from the broadband RF aperture array, and to digitize the broadband RF signal data to generate digitized broadband RF signal data, and to store the digitized broadband RF signal data locally at the RF receiver. The computer receives the digitized broadband RF signal data stored locally at the at least one RF receiver, and is programmed to reconstruct an RF image from the digitized broadband RF signal data received from the at least one RF receiver.

First claim

The invention claimed is:

1. A broadband radio frequency (RF) imaging device comprising:
a broadband RF aperture array comprising a differential segmented aperture (DSA) having at least four array elements and having a bandwidth of at least 700 MHZ;
at least one RF receiver; and
a computer;
wherein the at least one RF receiver is configured to digitize broadband RF signal data received by the broadband RF aperture array to generate digitized broadband RF signal data; and
wherein the computer is programmed to reconstruct an RF image from the digitized broadband RF signal data.

2. The broadband RF imaging device of claim 1 wherein the at least one RF receiver generates a local oscillator (LO) signal that is transmitted to the broadband RF aperture array, and the DSA includes:
a two-dimensional array of electrically conductive tapered projections wherein neighboring pairs of the electrically conductive tapered projections form RF pixels; and
RF mixers, wherein each RF mixer is connected to mix the RF signal received by a corresponding RF pixel with the LO signal to generate an RF intermediate frequency (IF) signal, the broadband RF signal data received by the at least one RF receiver being IF signals output by the RF mixers of the DSA.

3. The broadband RF imaging device of claim 2 wherein each RF mixer includes an anti-aliasing filter.

4. The broadband RF imaging device of claim 1 wherein the at least one RF receiver includes a plurality of RF receivers, and the two-dimensional array of electrically conductive tapered projections is disposed on two or more substrates whereby the DSA comprises a corresponding two or more DSA tiles, each DSA tile having RF connections with at least one RF receiver.

5. The broadband RF imaging device of claim 1 wherein the at least one RF receiver includes a plurality of RF receivers, the broadband RF imaging device further comprising a reference oscillator outputting a reference signal to the RF receivers to synchronize the RF receivers.

6. The broadband RF imaging device of claim 5 wherein the reference oscillator comprises a Global Positioning System (GPS) disciplined oscillator.

7. The broadband RF imaging device of claim 1 further comprising:
an Ethernet hub via which the computer is connected to receive the digitized broadband RF signal data from the at least one RF receiver.

8. The broadband RF imaging device of claim 1 further comprising:
a calibration RF signal antenna positioned at a predefined location respective to the broadband RF aperture array and configured to output a calibration RF signal at a predefined time;
wherein the computer is programmed to reconstruct the RF image by operations including performing frequency and/or phase correction of the digitized broadband RF signal data based on the predefined location and a portion of the digitized broadband RF signal data representing the calibration RF signal received at the broadband RF aperture array.

9. A broadband radio frequency (RF) imaging method comprising:
receiving a broadband RF signal from a physical environment with a broadband RF aperture array having a bandwidth of at least 700 MHZ, wherein the broadband RF aperture array comprises a differential segmented aperture (DSA) and the receiving of the broadband RF signal from the physical environment includes detecting RF signals using RF pixels of the DSA wherein each RF pixel comprises a neighboring pair of electrically conductive tapered projections of the DSA;
digitizing the received broadband RF signal with at least one RF receiver to produce a digitized broadband RF signal; and
using a computer, reconstructing an RF image of the physical environment from the digitized broadband RF signal data.

10. The broadband RF imaging method of claim 9 wherein the receiving of the broadband RF signal from the physical environment further includes:
generating a local oscillator (LO) signal using the at least one RF receiver;
transmitting the LO signal from the at least one RF receiver to the DSA;
at the DSA and for each RF pixel of the DSA, mixing the signal RF detected using the RF pixel with the LO signal using a mixer integrated with the DSA to generate an intermediate frequency (IF) signal, wherein the received broadband RF signal data comprises the IF signals output by the RF mixers of the DSA.

11. The broadband RF imaging method of claim 10 wherein generating of the IF signal further includes performing antialiasing filtering of the IF signal.

12. The broadband RF imaging method of claim 9 wherein at least one RF receiver includes a plurality of RF receivers and the receiving of the broadband RF signal from the physical environment further includes:
synchronizing the RF receivers using reference RF signal that is output to the RF receivers by a reference oscillator.

13. The broadband RF imaging method of claim 12 further comprising generating the reference RF signal using a Global Positioning System (GPS) disciplined oscillator in which a crystal oscillator is disciplined by a GPS receiver in a tracking loop.

14. The broadband RF imaging method of claim 12 further comprising:
an Ethernet hub via which the computer is connected to receive the digitized broadband RF signal data from the plurality of RF receivers.

15. The broadband RF imaging method of claim 9 further comprising:
during a predefined time, outputting a calibration RF signal from a predefined location;
wherein the reconstructing of the RF image of the physical environment includes performing frequency and/or phase correction of the digitized broadband RF signal data based on the predefined location and a portion of the digitized broadband RF signal data representing the calibration RF signal received at the broadband RF aperture array.

16. A broadband radio frequency (RF) test device comprising:
a differential segmented aperture (DSA) comprising a two-dimensional array of electrically conductive tapered projections;
at least one RF receiver configured to digitize RF signal data received by the DSA; and
a computer programmed to perform processing of the digitized RF signal data.

17. The broadband RF test device of claim 16 wherein the at least one RF receiver includes a plurality of RF receivers, the broadband RF test device further comprising a Global Positioning System (GPS) disciplined reference oscillator outputting a reference signal to the RF receivers to synchronize the RF receivers.

18. The broadband RF test device of claim 16 further comprising:
a calibration RF signal source positioned at a predefined location respective to the DSA and configured to output a calibration RF signal;
wherein the processing of the digitized RF signal data performed by the computer includes performing frequency and/or phase correction of the digitized RF signal data based on the predefined location and a portion of the digitized RF signal data representing the calibration RF signal.

Assignees

• Battelle Memorial Institute

Inventors

• Engel Mollie A
• Thornton Douglas A
• Welsh Raphael J

Classifications

• H04B1/006

  using switches for selecting the desired band (H04B1/0057 takes precedence) · CPC title

• G01S13/0209

  Systems with very large relative bandwidth, i.e. larger than 10 %, e.g. baseband, pulse, carrier-free, ultrawideband · CPC title

• G01S7/4021

  of receivers · CPC title

• G01S7/03

  Details of HF subsystems specially adapted therefor, e.g. common to transmitter and receiver · CPC title

• H01Q1/02

  Arrangements for de-icing; Arrangements for drying-out {; Arrangements for cooling; Arrangements for preventing corrosion} · CPC title