Effect of Measurement Distance on Gain Calibration of Pyramidal Horn Antenna

Numerical simulations of the gain and phase center measurements for a pyramidal horn antenna are carried out. The electromagnetic simulation is based on the finite integration method. The gain of horn antennas varies with the distance between their apertures, even if the antennas satisfy the far-field criterion. This gain variation is shown to correspond with the ratio of the distance between the apertures to the distance between the phase centers. The experimental results also demonstrate the efficacy of considering the location of the phase center for antenna calibration.