A Frequency and Pattern Reconfigurable Center Shorted Microstrip Antenna
A frequency and pattern reconfigurable antenna based on a center shorted microstrip patch is presented. The novel design utilizes two resonance modes of a microstrip antenna with shorting vias at the patch center. To set up the antenna tuning mechanism, two groups of varactors with a measured tuning range of [0.149, 1.304] pF are placed at two opposite sides of the antenna, followed by open circuited loading stubs. For a particular bias voltage configuration, the structure operates as a dual band antenna with broadside radiation at the upper resonance frequency and monopole like radiation at the lower band. By varying the dc bias voltage, both resonance frequencies can be changed simultaneously. Based on the proposed concept, a demonstration antenna has been designed so that the two types of aforementioned patterns can be reconfigured across a continuous fractional frequency range of more than 20% Experimental results are provided, which validate the proposed concept and design procedure.
IEEE Antennas and Wireless Propagation Letters