A Passive Auto-Switching Amphibian Antenna

An amphibian antenna was constructed that is capable of radiating both above and below the surface of water. The antenna is effectively a dual band PIFA design where each radiating element is tuned to resonate in close proximity of either air or water. A tuning stub was switched into circuit by the use of a passive, water filled, capacitive microstrip switch. The antenna was designed to operate at 433 MHz and good input impedance was observed in both simulation and measurement for both environments.