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Abstract-A wideband high-isolation two-port antenna of low profile and omni-directional pattern is presented. This 2-port system consists of a collocated antenna pair with a cone antenna in the middle and a ring radiator around the cone, both placed over a rectangular ground plane. The overall dimensions are 0.64λ 0.64λ 0.11λ at the lowest frequency of operation. The isolation between the two ports is more than 37dB and achieved by employing polarization orthogonality. The operational band is from 800 MHz to 2700MHz and the achieved isolation is verified with measurements of a fabricated prototype. Overall, the proposed antenna pair can be employed for simultaneous transmit and receive (STAR) applications or MIMO and diversity systems in commercial wireless communication bands. Index Terms-Ultra wideband antennas, Omnidirectional antennas, MIMO, simultaneous transmit/receive antenna

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The authors report the design of an ultra-wideband (UWB), dual-polarised, tightly coupled dipole array (TCDA) with an integrated balun for wide-angle scanning. A dual-pol dipole design enables massive bandwidth, large scanning volume, and high polarisation purity, concurrently. To achieve wide-angle impedance matching without exciting surface waves, two types of superstrates are evaluated on a finite array: (i) dielectric superstrate and (ii) novel planar frequency-selective surface (FSS). The latter architecture is capable of scanning 70° in E-plane and 65° in H-plane and shows, on average, 5° scanning improvement to the former. The impedance bandwidth is 5.25:1 (0.8-4.2 GHz) at the broadside (voltage standing wave ratio (VSWR)<2). The bandwidth reduces to 4.3:1 (0.9-3.9 GHz) when the maximum scanning angle or θ max increases to 65° for the H-plane and 70°f or the E-plane (VSWR < 3.2). The proposed array is a great candidate for wide-angle wideband scanning applications covering the entire L and S bands.