Antenna gain is an important metric for most modern communication systems. It can be determined several ways, but most commonly by producing an incident plane wave using a reference antenna, and measuring the received power at the antenna of interest. By measuring the received power several wavelengths away in an isolated environment, like an anechoic chamber, the antenna gain can be determined. This and other similar methods work well for frequencies above 2 GHz, but lower frequency measurements can be logistically challenging and expensive due to the large facilities required, as well as the lack of readily available broadband absorber materials. This work presents a new method for determining antenna gain using a transmission line based near field S-parameter measurement in a waveguide. To provide evidence for the proposed method, two monopole antennas are modeled over an infinite ground plane using full wave electromagnetics, and both are experimentally measured within a waveguide. It was found that there is very good agreement between the model and measurement, providing evidence of the validity of the method.
