Axial Ratio and Gain Measurements for Circularly-Polarized Antenna using Two Identical Antennas

An efficient method of measuring the axial ratio (AR) and realized gain is proposed for circularly-polarized antennas. The setup involves a transmitting-receiving system with two identical antennas and a vector network analyzer. The transmission coefficients of the transmitting-receiving system when the receive antenna is rotated by angle 0° and 90° are sufficient to obtain the AR, the realized gain, and the sense of rotation. A narrowband circular polarized patch antenna is simulated to validate the method over a large AR variation range. The excellent agreement between the simulated and calculated results demonstrates the accuracy of the method.