Slotfed switched patch antenna for multiple frequency operation

A switchable microstrip patch antenna for multi-frequency operation is presented. The antenna is fed by a coplanar waveguide via capacitive coupling slot. The antenna allows easy reconfigurability of the frequency band of operation by incorporating switches in the coupling slot. The resonant frequency of the antenna can be adjusted by setting the switches on or off. Two prototypes are presented. The first incorporates two PIN diodes and capable of switching between four frequency bands, over a frequency range of 1:23: 1. The second prototype incorporates four PIN diodes and is capable of switching between eight frequency bands, over a frequency range of 1:5: 1. The structure has a compact and simple biasing circuit. Simulation and measurement indicate that the proposed antennas demonstrate very good impedance matching, stable radiation patterns and good gain at all frequency bands.