Design of a CPW fed compact bow-tie microstrip antenna with versatile frequency tunability

A compact coplanar waveguide (CPW) fed frequency reconfigurable bow-tie microstrip antenna is proposed and experimentally verified which can be tuned at different bands between 1.94 and 3.27 GHz in single-band and dual-band modes. Two slots are carefully introduced on the ground plane of the antenna where two active varactor diodes are placed to vary its fundamental mode of radiation by variation of capacitance. To validate the antenna design, a fully functional prototype is fabricated and measured which ensures that the device can be operated at different frequencies of 2.02, 2.19 and 2.37 GHz with 35.9, 30.8 and 24.6% of impedance bandwidth, respectively, in the single-band mode. In dual-band reconfigurability mode, the resonant frequency of the antenna can be varied at 2.08, 2.17 and 2.3 GHz with a higher mode band within 2.7 and 3.3 GHz. The antenna shows maximum gain of 1.33 dB with 96.9% efficiency and 1.5 dB with 95.4% efficiency for single-band and dual-band reconfigurability mode, respectively. More importantly, the antenna has a compact dimension (0.31λ×0.32λ×0.0103λ at 1.94 GHz) and it produces symmetrical monopole type radiation pattern at all tunable bands.