POLARIMETER APPARATUS

• US 3,836,973 A
• Filed: 09/29/1972
• Issued: 09/17/1974
• Est. Priority Date: 09/29/1972
• Status: Expired due to Term

• Current Assignee: Albert Tashjian, Edward J. Shubel, Harold Shnitkin
• Original Assignee: Albert Tashjian, Edward J. Shubel, Harold Shnitkin
• Inventors: Shnitkin, Harold, Tashjian, Albert, Shubel, Edward J.
• Primary Examiner(s): Wilbur, Maynard R.
• Assistant Examiner(s): Buczinski, S. C.
• Application Number:
  US05/293,443
• Time in Patent Office: 718 Days
• Field of Search: 343/113R,1PE
• US Class Current: 342/362
• CPC Class Codes: G01R 29/0892 Details related to signal analysis or treatment; presenting results, e.g. displays; measuring specific signal features other than field strength, e.g. polarisation, field modes, phase, envelope, maximum value
• CPC Class Codes: H01Q 21/24 Combinations of antenna units polarised in different directions for transmitting or receiving circularly and elliptically polarised waves or waves linearly polarised in any direction circularly polarised patch antennas H01Q9/0428; circularly polarised horns H01Q13/0241; cross-polarised horns H01Q13/0258; polarisation converters H01Q15/242; cross-polarised rear feeds H01Q19/136; crossed polarisation dual antenna H01Q25/001
• CPC Class Codes: H01Q 21/245 provided with means for varying the polarisation polarising devices H01Q15/24; tracking by comparing linear polarisation compounds G01S3/146; reducing depolarisation effects H04B7/00; polarisation diversity H04B7/10

Abstract

An antenna and receiver system measures the polarization characteristics of an incident radio frequency signal. The system employs a signal processor for generating digital output signals indicating the angular orientation of the electric field vector of the arriving wave for a linearly polarized wave, or the degree of ellipticity and the orientation of the major axis for elliptically polarized incident waves. The signal processing is accomplished by means of a signal adder, six channels of log IF amplification and three video difference amplifiers.

Claims

1. Polarimeter apparatus for measuring instantaneously and continuously the polarization characteristics of an incident electromagnetic wave comprising a vertically polarized antenna and a horizontally polarized antenna in orthogonal arrangement for respectively detecting the vertically polarized component and the horizontally polarized component of said incident wave;

mixer means connected to the outputs of said vertically polarized and horizontally polarized antennas to produce at its output first and second voltage signals representing said vertically polarized and horizontally polarized components respectively;

signal adder means having its input connected to said mixer means output operative to simultaneously produce at its output, said first and second voltage signals, including third, fourth, fifth and sixth voltage signals comprising respectively the sums of said first voltage signal and said second voltage signal shifted in phase by first, second, third and fourth phase shift angles respectively;

signal processing means operative to process said third and fourth voltage signals to thereby derive as a function thereof, the axial ratio of said incident wave and to simultaneously process said first, second, fifth and sixth voltage signals to thereby derive as a function thereof, the polarization angle and sense of rotation of said incident wave simultaneously with said derivation of said axial ratio.

2. Apparatus as defined in claim 1 wherein said vertically polarized antenna comprises two vertical log-periodic dipole arrays and said horizontally polarized antenna comprises two horizontal dipole arrays.

3. Apparatus as defined in claim 2 wherein said vertical and horizontal dipole arrays are arranged in a symmetrical pyramid form.

4. Apparatus as defined in claim 3 wherein said two vertical dipole arrays are connected through a symmetrical tee-junction to form said vertically polarized antenna with its phase center on the axis of said pyramid, and said two horizontal dipole arrays are connected through a symmetrical tee-junction to form said horizontally polarized antenna with its phase center coincident with that of said vertically polarized antenna.

5. Apparatus as defined in claim 1 wherein said first phase shift angle associated with said second voltage signal is +90* representing right-handed circular polarization and said second phase shift angle associated with said second voltage signal is -90* representing left-handed circular polarization.

6. Apparatus as defined in claim 1 wherein said third phase shift angle associated with said fifth voltage signal is 0* representing +45* linear polarization and said fourth phase shift angle associated with said second voltage signal is 180* representing -45* linear poLarization.

7. Apparatus as defined in claim 5 wherein the axial ratio is derived by said signal processing means in accordance with the following relationship:

AR 20 log ((V1/V2) + 1 /(V1/V2) -

     1) where AR is the axial ratio, V1 is said third voltage signal and V2 is said fourth voltage signal.

8. Apparatus as defined in claim 6 wherein the polarization angle is derived by said signal processing means in accordance with the following relationship:

Tau 1/2 arctan ((V3/V4)2 + 1/(V3/V4)2 - 1 . (V5/V6)2 - 1/(V5/V6)2 +

     1) where Tau is the polarization angle, V3 is said first voltage signal, V4 is said second voltage signal, V5 is said fifth voltage signal and V6 is said sixth voltage signal.