Contents Introduction
The direct pulse modulation of a carrier wave by incorporating fast-switching semiconductor devices into an antenna structure and biasing them with a baseband information signal has recently emerged as a promising technique for improving communication system bandwidth [1], [2]. In order to refine and expand upon this technique, known as direct antenna modulation, the specific physical mechanisms behind the direct carrier wave pulse modulation must be fully understood. An electromagnetic simulation model of an L-band microstrip patch antenna with integrated PIN diodes [3] is constructed using Ansoft High Frequency Structure Simulator (HFSS) [4] and is analyzed to explore how the antenna's input impedance, center frequency and carrier wave radiation pattern are impacted by biasing the PIN diodes with a baseband modulation signal. By exploring the radiation characteristics of this specific example of direct antenna modulation, as applied to a patch antenna structure, the first steps are taken towards a general model of the direct antenna modulation technique.
