Low-Profile Wideband Slot Antenna Using Hybrid Resonant Mode Based on MISL Technology

In this paper, a novel low-profile wideband cavity-backed slot antenna (CBSA) based on the metal integrated suspended line (MISL) structure is proposed. To increase the bandwidth, three different resonant modes are investigated. Initially, an improved antenna based on the patch mode is developed from the MISL structure, and the characteristics of the patch mode are thoroughly studied. To enhance the bandwidth, the cavity mode inherent to the MISL structure is introduced, forming a simple hybrid mode antenna by combining the cavity mode with the patch mode. Moreover, to further extend the bandwidth, a slot is incorporated into the patch, achieving a quad-mode hybrid wideband antenna that integrates slot dual modes, cavity mode, and patch mode. Owing to the inherent all-metallic characteristics of the MISL structure, the antenna is capable of achieving high gain and low-profile while realizing wideband operation. Experimental results demonstrate that the proposed CBSA operates within a frequency range of 7.08-11.5 GHz, achieving a bandwidth of 47.6% and a maximum gain of 10.6 dBi with the size of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\boldsymbol 1.14\lambda \times 1.13\lambda \times 0.17\lambda \unboldmath$</tex-math></inline-formula>. This successfully realizes an excellent balance between wideband performance, high gain, and low-profile.