An improved model for the resonant frequency of tunable rectangular microstrip antenna

An improved model for the resonant frequency of a tunable rectangular microstrip antenna is presented. The influence of fringing fields and air gap between the dielectric substrate and ground plate on the resonant frequency is taken into consideration by introducing effective width W/sub eff/ and effective length L/sub eff/, equivalent permittivity /spl epsiv//sub r,equ/ and dynamic permittivity /spl epsiv//sub r,dyn/. The theoretic values are compared with experimental values, showing good agreement.