Novel Multi-Band SIW Antenna with Filtering Function

In this paper, the basic structure of a quad-band substrate-integrated waveguide (SIW) antenna with filtering characteristics is proposed. The proposed antenna consists of a four-slot SIW and a single-probe feed. Despite having a single feed, it was able to independently control the four resonant frequencies. However, since a basic quad-band SIW antenna has three radiation null frequencies, the left skirt characteristics of f1 and the right characteristics of f4 were not good. To improve this, four pairs of vias and a pair of U-slots were introduced to add two radiation null frequencies to the lower part of f1 and the upper part of f4, respectively. This time, the parameters of the basic structure did not change, except for those of the added structure. The fabricated antenna operated at 3.9, 4.03, 4.2, and 4.3 GHz, and exhibited a radiation null below -15.6 dBi at 3.6, 3.95, 4.09, 4.27, and 5.07 GHz.