A.A. Gavrilov, O.A. Kurdjumov, V.E. Sagach
In antenna gain measuring practice with elliptically polarized antennas (EPA) it was found that the implementation of different techniques gives different results. Concretely the comparison of two or three antenna etaloning techniques or comparison techniques with etalon antenna gives different results in measurements.
To understand the issues of disagreements in experimental gain measurement results of EPA using different techniques, the evaluation of radio communication formula (RCF) for a pair of EPA and different combinations of randomly polarized antennas was analytically considered. In case when EPA is transmitting antenna and LPA (linearly polarized antenna) and otherwise, a seeming disagreement in duality principle was founded. This «paradox» is eliminates by analyzing the receiving EPA scheme as tourniquet antenna. The tourniquet antenna is presented as two half wave vibrators connected to receiver across the quadrature hybrid coupler. Described scheme of EPA is also presented in, for example, microstrip antennas with two feed points.
Then, different gain measurement techniques with included corrections for RCF were experimentally tested using network analyzer in anechoic camera. The measurements were realized on spiral antennas developed in ISDE on the frequency of 2.212 GHz. The wideband horn LPA «P6-23A» used as etalon antenna.
The same results in gain measurement technique with proposed corrections in RCF, certainly: technique of two LPA and one EPA, technique of three random EPA, techniques of two same EPA, comparison technique using transmitting EPA and etalon LPA, and comparison technique using transmitting LPA and etalon LPA verifies the accuracy of included corrections.
Basing on obtained result, it is possible to make conclusion that the RCF must be modified to the antenna polarization-dependant view. Thus, the gain calculation formulas in measuring techniques by experimental results also must be modified