Far Field Gain Estimation Method for Japanese Broadband Antenna Standard Using Time-frequency Analysis

We are developing a far field gain and antenna factor estimation method for Japanese broadband antenna standards. We have already proposed a method for estimating the free space antenna factor of broadband antennas using a time-domain analysis and a pulse compression technique. However to estimate the antenna factor and gain, we are using fixed antenna distance. In this paper, we propose a new estimation method for determining the antenna distance at each frequency that to estimate the far field antenna gain. Our proposed method is based on the techniques of a time domain analysis and a time-frequency analysis using a short time Fourier transform. In the case of biconical antenna, the difference between far-field gain and the estimated near-field gain using our proposed method is less than 0.05 dB at 10 m antenna distance and less than 0.25 dB at 3m antenna distance in the frequency range from 30 MHz to 220 MHz.