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A broadband stacked patch antenna array with high port isolation is presented for in-band full-duplex (IBFD) applications in this article. A co-channel feeding scheme is proposed to simultaneously excite two ports of the patch antenna to achieve ± 45°dual polarization. An antenna system is then designed using a 2 × 2 stacked patch array, a parallel feeding network, and a hybrid coupler. The coupling between the Tx and Rx ports due to mismatch and coupling between the antenna elements is analysed in detail and shown to be eliminated completely. A demonstrator is fabricated and measured to endorse the accuracy of the proposed feeding scheme. The measured results show that the developed prototype can operate from 3.15 GHz to 4.0 GHz. The isolation level between Tx and Rx ports is higher than 45 dB within the operating band. The realized gains of two ports are higher than 10.5 dBi throughout the band of interest with the maximum gain of 13.9 dBi, which are congruent with the simulated ones. [ABSTRACT FROM AUTHOR]

This paper proposes a compact and broadband dual-polarized base station antenna based on current path extension for 2G/3G/LTE base stations. The antenna is miniaturized by bending the end of the radiator to extend the current path. By bending the antenna, a new resonant mode is introduced to increase the bandwidth. In addition, a parasitic patch is placed above the antenna to improve impedance matching, and the introduction of artificial magnetic conductors reduces the profile of the antenna and significantly improves the radiation characteristics. The antenna radiator has a compact size of only 0.207 × 0. 207 λ L 2 at the lowest frequency with a total profile of 0.136 λ L. The measured results indicate that the proposed antenna has a substantial bandwidth of 45.5% and more than 34 dB of high port isolation with a gain of 7.9 ± 0.5 dBi. [ABSTRACT FROM AUTHOR]

A wideband and high-isolation mobile phone antenna pair with low envelope correlation coefficient (ECC) for fifth-generation (5G) smartphone applications based on four orthogonal modes is proposed in this communication. According to the characteristic mode analysis, except for the original two resonant modes, the other two resonant modes are introduced by arranging a metallic strip at the top of the vertical bezel. With the help of dual-mode excitation and orthogonal property, wideband and high-isolation merits are achieved for the shared radiator antenna pair. Finally, four antenna modules are deployed along the long edge of the system circuit board to form an 8 × 8 multiple-input multiple-output (MIMO) system. The measured results prove that the impedance matching bandwidth of the fabricated prototype ranges from 3.3 to 5 GHz while the isolation level is higher than 17.5 dB. The antenna efficiencies are higher than 45% and 48% for the two different antenna elements. Guaranteed by the orthogonal relationship between different characteristic modes, the extremely low ECC (< 0.04) is achieved. [ABSTRACT FROM AUTHOR]

This paper proposes a duplex dual circularly polarized antenna, using four half-Vivaldi antennas to form a sequential rotation array, which can generate circular polarization by sequential feeding. A mental cavity and half of a Vivaldi antenna form a new Vivaldi antenna. The Vivaldi antenna has broadband characteristics to cover the uplink and downlink bands and is compact with an area of 0. 69 λ c × 0. 69 λ c . To achieve duplex dual circular polarization, a feeding network that can sequentially output + 90 ° and − 90 ° is designed. The feeding network, which contains two broadband power dividers, two directional couplers and two phase-shifters, generates the sequential feeding signals for sequential rotation group array with equal amplitude and ± 90 ° phase difference. Both the impedance bandwidth and the 3 dB axial ratio bandwidth of the transmitter and receiver can cover the band of 10–15 GHz. The gain of the antenna is higher than 5.75 dBi. The isolation between the receive and the transmit ports can reach 25.49 dB or higher in the uplink band. [ABSTRACT FROM AUTHOR]