Measurement of Antenna Gain with Transmitting and Receiving Antennas on a Finite Ground Plane; Interim rept

摘要

The gain of an antenna is usually measured by placing a transmitting antenna in the far field of the antenna under test (AUT) and then comparing the power received by that antenna with that received by a reference antenna (RA). Rather than having a separate power source for the transmitter, it is convenient to utilize the two ports of a Hewlett-Packard 8510C Network Analyzer for the gain measurement. There are however some obstacles that arise when using this approach, particularly if the AUT has low gain and is to be measured over a wide frequency band. In order to overcome the above limitations we investigated an approach where the transmit antenna is a resonant monopole which is mounted on the same ground plane as the AUT and RA, which is also a resonant monopole. The resonant frequency of each monopole can be easily changed by using a telescoping arrangement. We review the theory and then present simulations and measurements when both transmitting and receiving antennas are mounted on a 4-ft x 4(question mark)ft (1.22 m x 1.22m) ground plane for the frequency range from 200 MHz to 1000 MHz. The agreement between theory, simulations and measurements is very good.