Correcting Instable Signal in Near-Field Antenna Gain Measurement

摘要

This paper describes a technique for correcting errors caused by a signal's drift over time during a near-field antenna gain measurement. Our error correction technique is composed of the following two steps. (1) A near-field signal is corrected by using the reference signal power curve. The reference signal powers at a certain position of the probe antenna are measured during NFM for both a standard gain antenna (SGA) and the antenna under test (AUT). (2) The signal power difference between the end and start of the first antenna measurement is used to correct the signal power of the second antenna measurement. The second step is newly introduced in the paper. When a signal radiated from an offset parabolic-reflector antenna was measured twice consecutively at 28 GHz, the gain difference between the two measurements obtained using error correction techniques (1) and (2) was 0.06 dB; without error correction it was -0.24 dB; with error correction (1) only it was -0.59 dB. The measurement results at 40 GHz indicated a similar trend. The gain differences, which can be measurement errors caused by the signal drift, almost satisfied the requirement for measurement accuracy.