Compact Dual-Band Circularly Polarized Stacked Patch Antenna for Microwave-Radio-Frequency Identification Multiple-Input-Multiple-Output Application

Abstract

A compact, low-profile, two-port dual-band circularly polarized (CP) stacked patch antenna for radio-frequency identification (RFID) multiple-input-multiple-output (MIMO) readers is proposed, which employs the shared-aperture technique. The proposed antenna adopts a 1.524 mm thickness Rogers Ro4350b substrate with relative permittivity of 3.48. Two pairs of isolated ports are working at two microwave- (MW-) RFID bands (2.4–2.485 GHz and 5.725–5.875 GHz) with high port isolation of 25 dB and 30 dB, respectively. A shared metal slot layer is designed to separate two feeding structures of the lower band and upper band for port isolation enhancement as well as saving space. Corner-truncated square slot and patch configurations have been designed to obtain CP modes. In the lower and upper MW-RFID bands, the relative impedance bandwidths are 12.2% and 5.7%, and the maximum realized gains are higher than 7.3 dBic. Moreover, two-element configurations have been combined for an RFID MIMO system that occupies a dimension of 119 mm × 119 mm × 12.9 mm. The MIMO antenna performance of envelope correlation coefficient (ECC) is lower than 0.03, and diversity gain is close to 10 dB.

Broadband and Compact Circularly Polarized MIMO Antenna With Concentric Rings and Oval Slots for 5G Application

“…latency, faster mobility, high data throughput, and reliable communication [6], [7]. Therefore, MIMO antenna designs with CP senses have been reported in recent years [8]- [16].…”

“…Stacked patch MIMO antennas have the features of wideband/multiband and performance enhancement. Therefore, the work in [8]- [10] has applied the stacked patch technique to the CP MIMO antennas. In [8], corner-truncated square slot and patch configuration are applied to the MIMO antenna to yield CP radiations in 2.45 GHz and 5.8 GHz bands.…”

“…Therefore, the work in [8]- [10] has applied the stacked patch technique to the CP MIMO antennas. In [8], corner-truncated square slot and patch configuration are applied to the MIMO antenna to yield CP radiations in 2.45 GHz and 5.8 GHz bands. In [9], the CP is achieved by protruding a stub from the right end of the ground plane, whereas the method applied by [10] is to chamfer the two opposite corners of the ring slot as well as the resonant patch.…”

“…In [9], the CP is achieved by protruding a stub from the right end of the ground plane, whereas the method applied by [10] is to chamfer the two opposite corners of the ring slot as well as the resonant patch. However, the MIMO antennas in [8] and [10] have exhibited larger dimensions, and the ones in [8] and [9] have used expensive substrates. Notably, applying the stacked patch technique will inevitably increase the overall profile of the designated antenna, which makes it difficult to integrate into a slim wireless device.…”

“…Notably, applying the stacked patch technique will inevitably increase the overall profile of the designated antenna, which makes it difficult to integrate into a slim wireless device. Even though [11] has introduced a compact CP MIMO antenna designed using two truncated corner square patches with parasitic periodic metallic plates [11], it requires expensive Taconic substrate (same as [8], [9]) that results in higher manufacturing expenses.…”