Triple slot arm loaded reconfigurable dual frequency microstrip antenna using varactors

A novel design of a varactor controlled electronically reconfigurable dual frequency microstrip antenna is presented. Dual frequency operation is realized by embedding a hexagonal slot with extended slot arms within a square patch. Varactor diodes integrated with the slot arms are used to tune the operating frequencies considerably, by applying reverse bias voltage. High tuning ranges of 20.75% and 14.36%, respectively, are realized for the two resonant frequencies when the bias voltage is varied from 0 to -30V. This design has the added advantage of up to 69.6% and 50.9% size reduction for the two resonant frequencies compared to the standard rectangular patch. Maximum band widths of 2.1486% and 1.2960% for the two frequencies, with the operating frequency ratios varying in the range 1.2031 to 1.2704, are observed.