Frequency-Reconfigurable Coplanar Patch Antenna With Conical Radiation

A design for frequency-reconfigurable antennas with conical-beam radiation is described. The design is based on the TM02 mode of a coplanar annular-ring microstrip antenna, and several shorting strips are symmetrically placed along the circumference of the radiating patch to vary its resonant frequency. The effects of the number of the shorting strips on the resonant frequency and radiation characteristic are respectively investigated. The obtained results indicate that the resonant frequency of the microstrip antenna has an increase of 33% when the number of the shorting strips is varied from 0 to 16. In addition, the antenna radiation can remain the conical beam pattern with the increasing of frequency. A frequency-reconfigurable prototype with electrical switching between 4.8 and 6 GHz has also been fabricated, and the experimental results are given.