A Millimeter-Wave Triple-Band SIW Antenna With Dual-Sense Circular Polarization

A millimeter-wave (mmWave) triple-band substrate integrated waveguide (SIW) antenna with dual-sense circular polarization (CP) etched on a single substrate is proposed. A SIW cavity operating in TM210 mode is carved with a circular slot to realize upper band radiation. A circular patch is placed in the circular slot for lower band radiation. Middle band radiation is realized by the coupling between the SIW cavity and circular patch. By introducing asymmetry on both circular slot and circular patch, CP is obtained at two bands. The polarization states of the three bands are right-hand circular polarization (RHCP), linear polarization (LP), and left-hand circular polarization (LHCP). Three pairs of vias are introduced in the SIW transmission line to realize good impedance matching for the three bands. A prototype is fabricated and its performances are evaluated. Simulated and measured results agree very well. Small frequency ratios are achieved and each band can be adjusted flexibly. The proposed antenna has characteristics of low-profile and simple structure which will make it easy to be applied in future mmWave wireless communication systems.