Abstract
A practical method, which based on eighth-mode substrate integrated waveguide (EMSIW), is investigated in this paper to design low-profile antenna with dual-sense circular polarization (CP) and enhanced bandwidth. First, an eighth-mode radiating cavities is presented and excited by single coaxial probe for size reduction and directional radiation. Then, two EMSIW antennas are placed symmetrically and a triangular parasitic patch is introduced between two EMSIW cavities. Attribute to the weakly coupled effect between the radiation aperture and triangular parasitic patch, dual-sense circular polarization characteristic and an additional resonance are acquired. When the triangular patch is transformed into a square parasitic patch, the current path on the parasitic patch is shortened, and a new resonance point is generated at 3.55 GHz. While the resonant mode of the two eighth-mode radiating cavities are almost unaffected and the CP bandwidth varies with the changed current path. Finally, a dual-sense CP EMSIW antenna with extended bandwidth and simple structure is designed and fabricated. The overall size of the fabricated prototype is only <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.57\lambda _{0} \times 0.54\lambda _{0} \times 0.02\lambda _{0}$ </tex-math></inline-formula> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{0}$ </tex-math></inline-formula> is the free-space wavelength at 3.4 GHz). Measured impedance bandwidth is 10.5% from 3.24 GHz to 3.60 GHz with an isolation up to 11.6 dB and a maximal gain better than 5.74 dBic in two ports is also achieved. Moreover, the characteristics of dual-sense CP and the cross-polarization suppression capability of up to 20 dB in the main beam are obtained in 3.48-3.60 GHz.
Highlights
In recent years, modern wireless communication technology has developed vigorously, followed by an increasingly complex and congested electromagnetic environment
As the shape of the parasitic patch changes, the gradual expansion of the bandwidth and the subsequent dual-sense circular polarization characteristics provide a new idea for the broadbandization and multi-polarization of multi-port eighth-mode substrate integrated waveguide (EMSIW) antenna
A simple structure dual-sense circular polarization broadband antenna based on the utilize of EMSIW technology is designed in this work
Summary
Modern wireless communication technology has developed vigorously, followed by an increasingly complex and congested electromagnetic environment. The SIW technology, which combines printed circuit board and periodically arranged metalized vias, is gradually employed to design the antennas with low profile, low cost, high gain, dual-band, and circular polarization [1], [4]. A simple dual-port circularly polarized EMSIW antenna is designed by combining two compact eighth-mode radiation cavities and a parasitic patch. As the shape of the parasitic patch changes, the gradual expansion of the bandwidth and the subsequent dual-sense circular polarization characteristics provide a new idea for the broadbandization and multi-polarization of multi-port EMSIW antenna. More than 10.5% impedance bandwidth displayed by the antenna prototype, measured gain up to 5.74 dBic, 3 dB axial ratio bandwidth of 120 MHz, port isolation up to 11.6 dB, simple structure and easy-to-process all indicate that the proposed antenna is extremely competitive for wireless communication
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