Electronically switchable slot antenna fed by microstrip line

Switching of antennas can be done with active components like PIN diodes, varactor diodes, or different types of transistors. In this paper varactor diodes were combined with transverse microstrip fed slot antennas to achieve electronic switching of slot antennas. The switching function of the transverse microstrip fed slot antenna was realized by turning the varactor diode on or off. When the diode was with the negative maximum DC bias voltage, the total impedance of the slot antenna was designed to be well matched to the feedline. The signal radiated out efficiently and the slot antenna was switched on. When the diode was with 0 VDC bias, the total impedance of the antenna structure was designed to be mismatched to the feedline. All power was reflected back due to the mismatch and hence the antenna was switched off.