High Gain Filter Circular Patch Antenna Without Extra Circuits Based on SISL

In this paper, A simple circular patch filtering antenna (CPFA) using substrate integrated suspension line (SISL) technology without extra circuits is proposed. The antenna is evolved from a single-layer circular patch antenna. First, introduction of stacked patch generates a radiation null, the frequency selectivity of the upper band is obtained. Meanwhile, stacked patch produce extra resonance mode broaden the fractional bandwidth. Second, taking advantage of the particularity of SISL structure, a novel through hole grounding method is introduced. In this way, the mode TM
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is generated in the lower band edge, thus introducing the low frequency radiation null. Therefore, three radiation nulls can be achieved without extra circuits, which makes the antenna design optimization simple. The simulation results show that the proposed antenna have an average gain of 9.05 dBi within passband, and out-of-band suppression levels of more than 16 dB. In addition, the antenna design is simple and compact, the height of the antenna is only 0.06λ
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.