Influence of Reflection Area on Calibration Accuracy by Single Antenna Method Using Broadband Antenna

We have already proposed the single antenna method for an antenna gain measurement of the log-periodic dipole array antenna (LPDA) and the double ridged guide horn antenna (DRGH). Our proposed single antenna method uses the metal ground plane as the electric mirror. In the measurement, the DRGH is set perpendicularly to the ground plane and electromagnetic absorbing materials are covered the ground plane for changing the reflection area of the ground plane. In the case of 3 m diameter of the reflection area at the antenna height of 5 m above the ground plane, the proposed method can completely separate the direct wave from other undesired waves from the absorbing materials. Further, we show the estimated antenna gain using Friis transmission formula at the phase center distance for our single antenna method.

I. Introduction

According to the Calibration and Measurement Capability (CMC) list, the three antenna method and the substitution method are conventionally used for the calibration of the broadband antenna in many countries. However, these methods need high cost and more time. On the other hand, the single antenna method is possible to calibrate an antenna gain in a shorter time and a lower cost than the conventional method. Furthermore, the measurement by the single antenna method does not need the experimental facility of large size such as the open area test site since it uses the image theory. The single antenna method is firstly proposed by Glimm et. al. [1] in 2000. We also have already proposed the single antenna method for an antenna gain measurement of the broadband antenna such as LPDA (the operating frequency is from 300 MHz to 1 GHz) and DRGH (the operating frequency is from 1 GHz to 6 GHz) [2], [3]. Our method makes it possible to measure separately the reflection wave at the metal ground plane and the intrinsic self-reflection wave of the antenna under test (AUT) using time-domain subtraction. To estimate far field antenna gain, we use the phase center modified Friis transmission formula [4], [5]. In this paper, to investigate the influence of the reflection area of the metal ground plane, the reflection area was changed by setting the absorbers on the metal ground plane. Fig. 1.

Setup for single antenna method.