An Active Cavity-Backed Slot Antenna Based on a Parametric Amplifier

In a parametric amplifier, nonlinear and/or time variant characteristics of reactors (capacitors and/or inductors) are exploited to amplify microwave signals. In this paper, an active parametric slot antenna is introduced by integrating varactor diodes as nonlinear capacitors to the radiative slot, which is cut through one side wall of a rectangular cavity resonator. To ease the design and tuning of the antenna, capacitively loaded TE011and TE021modes of the cavity are utilized as filters at signal and pump frequencies, respectively. In the proposed topology, the TE011mode excites a half-period sine-shape magnetic current across the slot leading to maximum radiation in the broadside direction at the signal frequency. At the same time, a full-period sine-shape magnetic current is excited through the slot by the TE021mode to maintain minimum radiation in the broadside direction at the pump frequency. A full-wave simulator [high-frequency structure simulator (HFSS)] alongside a circuit simulator [advanced design system (ADS)] is incorporated to simulate the entire antenna characteristics including radiation patterns and nonlinear parameters. The proposed structure is fabricated and measured to verify the theoretical and simulation results.