An Evanescent-Mode Cavity-Backed High-Power Tunable Slot Antenna

In this paper, a new high-power and tunable cavity-backed slot antenna is introduced and experimentally investigated. The proposed antenna is composed of a frequency-tunable evanescent-mode cavity resonator loaded with an annular radiating slot on the cavity back side. Frequency tuning is performed by changing the critical gap size over the resonator's post through a piezotuner disk. A prototype copper-machined fabricated antenna represents about 25% tuning (2-2.57 GHz) of the antenna's 10 dB reflection coefficient when the cavity gap size is varied in the range of 17-171 μm. The introduced antenna depicts ≈5 dBi of gain and radiation efficiency of more than 85%. Moreover, the antenna successfully handles 80 W of input power which can also be increased using a closed loop actuating system. In addition, the proposed antenna shows a good linearity due to the mechanical tuning scheme. Hence, this antenna is promising for high-power applications, which, at the same time, can also be realized on printed circuit boards (PCBs), making it easy for integration with circuits.