Performance of circularly polarized patch antennas for personal satellite communications including biological effects

Recently, considerable attention has been focussed on the design and implementation of satellite networks capable of providing world-wide telecommunications coverage. Naturally, an integral component of these systems is the portable transceiver handset which allows convenient communication at any remote location. When designing handsets for use in satellite-based systems one technical challenge is the requirement of supplying an antenna which provides circularly polarized radiation over a broad angular range. Novel antenna designs, such as the microstrip patch antenna presented in this paper, must be designed and evaluated if good engineering solutions are to be found. A key consideration in the evaluation of antennas for transceiver handsets is the effect of the operator´s biological tissue on the antenna radiation performance. This is particularly true for circularly polarized antennas for satellite networks, where the pattern polarization and shape characteristics may be of critical importance. Therefore, this paper uses a previously reported electromagnetic simulation tool based upon the finite difference time-domain (FDTD) algorithm to study the effect of the human body on the handset-mounted circularly polarized patch antenna. Within the FDTD methodology, detailed models of the head and hand are combined with a real-life model of the antenna on the handset to allow investigation of the antenna performance when it radiates in its true operating environment.