A Compact Reconfigurable Antenna With Wide Tunable Frequency and 360° Beam Scanning

A compact microstrip-fed antenna consisting of radiating rings and parasitic strips is proposed for frequency- and pattern-reconfigurability. The 24.7% frequency tuning range is achieved by controlling the input impedance at the rings using two varactor diodes. By regulating the radiation from the rings and changing the role of the strips from reflector to director (vice versa), nearly 360° azimuth beam-scanning is realized. A prototype is built and tested to validate the concept. Despite having a compact size and thin profile (0.27λ
₀
× 0.34λ
₀
× 0.005λ
₀
,λ
₀
at the lowest frequency), the antenna with its simplified mechanism possesses multiple functions that are comparable with array antennas for similar purposes.