Frequency-Agile Self-Diplexing Antenna

In this paper, a design of a self-diplexing substrate integrated waveguide (SIW) antenna with independently tunable frequencies is proposed. This antenna design has two sets of varactor diodes tuning the effective length of a SIW cavity with three apertures, thereby adding resonance frequency tunability for the diplexing frequencies. Based on the measured results, the lower diplexing frequency varies from 2.64 GHz to 2.82 GHz with the measured maximum realized gain varying from 4.9 dBi to 5.6 dBi. The higher diplexing frequency varies from 3.15 GHz to 3.41 GHz with the measured maximum realized gain varying from 4.6 dBi to 5.5 dBi. The simulated antenna total efficiency in both diplexing bands is better than 60%.