An offset-fed microstrip antenna with reusable harmonics based on a composite right/left-handed transmission line resonator

In this paper, a new reusable harmonic microstrip antenna with an offset feed is presented. The proposed antenna consists of 9 isotropic arranged square unit-cells with an offset-feed at the centre cell. Based on a composite right/left-handed transmission line (CRLH-TL) resonator and the cavity model of a microstrip antenna, additional resonant frequencies and radiation patterns are analyzed. Moreover, the theoretical approach is discussed for the proposed structure. The multiple resonant frequencies are occurred due to both of CRLH-TL and microstrip patch resonant characteristics. Particularly, the antenna has a gain of about 10 dBi and a patch-like radiation at the harmonic mode.