A switched polarization dual loop antenna for 2.4 GHz ISM band applications

A dual loop antenna has been designed for a 2.4 GHz ISM band application. The design uses a diode switch to alter the configuration of a single feed, two-loop antenna. One loop is always driven while the other acts as a counterpoise. It is an open or closed loop, depending on the state of the switch, and is simply connected to the ground lead of the antenna port. The pattern of the antenna switches between two significantly different states providing the required directional and polarization diversity. The impedance of the antenna also changes significantly and matching is addressed via a switched network. After the antenna simulations, electromagnetic and circuit simulations were used to model the matching and bias networks and their layout. Results are presented showing a complete design with acceptable performance. The simulation results were verified by comparison to measurements. This work linked several different electromagnetic simulation tools, with coupling of the results generated from them to construct accurate prototypes.