PLANAR NEAR-FIELD CALIBRATION OF DIGITAL ARRAYS USING ELEMENT PLANE WAVE SPECTRA

• US 20150349420A1
• Filed: 02/13/2015
• Published: 12/03/2015
• Est. Priority Date: 02/13/2014
• Status: Abandoned Application

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: O'Haver, Kenneth W.
• Application Number:
  US14/622,781
• Publication Number:
  US 20150349420A1
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H01Q 3/267 Phased-array testing or checking devices
• CPC Class Codes: H04B 17/12 of transmit antennas, e.g. of the amplitude or phase
• CPC Class Codes: H04B 17/21 for calibration; for correcting measurements
• CPC Class Codes: H04B 5/70 specially adapted for specific purposes
• CPC Class Codes: H04B 7/0617 for beam forming

Abstract

A calibration method, applicable to element-level digital arrays operating in the receive mode, which utilizes the individual element plane wave spectra obtained from a single planar near-field scan. The method generates highly accurate near-field measurement derived amplitude and phase calibration of both large and small digital arrays as a function of array scan. The present disclosure provides digital array calibration methods and their potential uses in satellites and directional arrays.

Claims

1. A method for calibrating phased array antenna system comprising:

performing, by at least one processor of a computing system, a first plurality of calibration activities comprising;

performing a near-field scan of a digital phased array comprising a plurality of elements and recording element digital I &

Q samples for each probe position;

converting the element digital I &

Q samples to amplitude and phase measurements;

computing a unit excitation plane wave spectrum for each element;

computing element amplitude and phase calibration coefficients as a function of steering angle; and

calibrating the digital phased array during operation of said digital phased array by adjusting the array and the array element operation or pattern based on said unit excitation wave spectrum data and element amplitude and phase calibration coefficients.

2. The method of claim 1, wherein the phased array antenna system comprises a digital array.

3. The method of claim 1, wherein said phased array antenna system comprises a satellite communications system.

4. The method of claim 1, wherein said phased array antenna system comprises a directional digital array having replaceable elements.

5. The method of claim 1, wherein the unit excitation plane wave spectrum is computed for each element using equations comprising

6. The method of claim 1, wherein the element amplitude and phase calibration coefficients are computed as a function of the steering angle using equations comprising Phase {ψ

_i(k_xo,k_yo)}=−

Phase {f_p′

ⁱ(k_xo,k_yo)} and