Free space antenna gain measurements by way of tracing the reflected waves in time domain

摘要

There exist reflected waves which obstruct measuring the free space antenna gains or factors in open area test site (OATS). The various methods to measure them with properly treating the reflected wave keep being tried [1,2,3]. Generally, the methods are given in the frequency domain. It was possible to measure the insertion loss S21 between two antennas in the frequency domain and mathematically calculate Inverse Fourier Transform of the data to give the time domain response [4]. There is a gap of the reaching time from Tx to Rx due to a path difference between the direct and reflected signal. If resolution is sufficient to distinguish between them, time domain analysis continues to be an effective tool which selectively removes unwanted responses like a reflected wave on open area test site. The time domain technology using a network analyzer and computer for antenna calibration is proposed for the first time [5]. It is applied to measuring the antenna factors of a dual ridged horn(l ∼ 9 GHz) and a biconical dipole(30 ∼ 300 MHz).