Differentially fed, dual-band filtering antenna with H-shaped slot

A differentially fed, dual-band microstrip patch antenna with filtering response is proposed in this letter. By etching an H-shaped slot at a rectangle radiating patch, two resonant modes of the patch antenna, as well as an additional radiation null between the two operation bands are generated. Besides, two symmetric open-stub coupling feedlines (OSCFs) are introduced to differentially excite the antenna, which offer two extra radiation nulls outside the two bands. Thus, a dual-band bandpass filtering response for the proposed antenna is obtained. Measurement results of the prototype show good agreement with the simulated ones. Stable radiation patterns with low cross-polarization levels of better than 28 dB are observed. Besides, a deep roll-off of better than 22 dBi for the realized gain is also obtained.