A miniaturized switchable SIW-CBS antenna using positive and negative order resonances

A switchable SIW-CBS antenna with two different operating bands using a new switching method is presented. The method uses the reactive loading effect of shortening posts inside the cavity to change the overall resonance order from negative to positive. In order to achieve the negative order resonance, a composite right/left-handed (CRLH) structure is used by inserting an interdigital slot on the top side of a SIW cavity instead of a conventional rectangular slot. Using a two-layer substrate structure the antenna is totally isolated from the biasing circuit. Thus, the operating resonance frequency can be easily tuned by switching the posts using p-i-n diodes. Using this technique and by switching between the negative and positive order resonances, a frequency tuning ratio (f_TR=f_up/f_low) of 2.7 (1.83-4.93 GHz) is achieved. The antenna shows similar radiation patterns with high purity and front-to-back ratio for both operating bands.