Low-profile Slotted SIW Cavity Backed Antenna for Frequency Agility

The agile frequency antennas are widely used for wireless communication systems. This paper studies and designs a low profile SIW antenna radiating from a circular slot graved in the ground plane, with the ability of alternating the frequency. The antenna is intentionally designed within a range of 1.8 GHz to 2.18 GHz obtained by varying the DC bias voltages from 0 to 26 V, which is able to cover the GSM1800, the LTE, and the UMTS wireless standards. The tuning technique consists in the integration of two varactor diodes across the circular slot. A prototype was manufactured, and the experiment results correspond well to those of the simulations.