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In this letter, a single-layer compact copolarized shorted TM1/2,0 mode microstrip patch antenna is presented for in-band full-duplex application. Two shorted TM1/2,0 mode patch antennas, used for transmission and reception purposes, make the structure compact. The wideband behavior of the patch antenna is obtained by fusing the two resonances, one because of the shorted TM1/2,0 mode radiating patch and the other because of the λ/4 line resonator. To enhance the isolation between the transmitter and receiver antenna, a novel defected ground structure is used. Slots are introduced into the ground plane to create a weak field region for the basic antenna element. The other antenna element (receiver) is located in the weak field region to enhance isolation. Further enhancement in isolation is achieved by introducing a T-shaped metallic strip into the slots. The structure is proposed with the credits of compactness, enhanced bandwidth, colinear polarization, very less fabrication complexity, low profile, and high isolation. The proposed structure is fabricated and measured. The structure experimentally exhibits a bandwidth (≤ −10 dB) of 2.42–2.52 GHz with the isolation of 25 dB, peak isolation of 36 dB, and an average realized gain of 4 dBi in the entire band. [ABSTRACT FROM AUTHOR]

A compact five-port multi-input multi-output (MIMO) antenna for n79 (4.4–5 GHz) 5G band exhibiting pattern and polarization diversity with good isolation is proposed in this paper. This MIMO antenna system comprises of four linearly polarized (LP) endfire monopole antenna elements and one broadside L-shaped slot circularly polarized (CP) antenna element, which provides both pattern and polarization diversity. A T-shaped slot as a decoupling structure is further used to improve the interport isolation by 4 dB. The return loss bandwidth for all antenna elements is in the desired frequency range, and antenna elements provide isolation better than 23 dB. The pattern and polarization diversity provide a low envelope correlation coefficient and good isolation between any two-port of the MIMO antenna. For experimental verification, the proposed 5-port MIMO antenna system is fabricated and measured, which provides decent agreement with the simulated performance. [ABSTRACT FROM AUTHOR]

A dual‐band, dual‐polarized in‐band full‐duplex antenna with good isolation performance is presented for wireless local area network (WLAN) applications. A neutralization line is connected between the grounds of the transmitter (Tx) and receiver (Rx) antennas to enhance the isolation. Further enhancement in isolation is achieved by using a 180° ring hybrid coupler between receiving antenna elements. Here the dual‐band monopole antennas are used as transmitting and receiving antenna elements. For better isolation, the receiving antenna elements are placed opposite to each other and fed through the differential ports of the 180° ring hybrid coupler. The proposed structure is fabricated, and the comparison of measured results and simulated results are studied. The simulated and measured impedance bandwidths (≤−10 dB) of the antenna cover the entire 2.4 GHz WLAN band (2.4–2.48 GHz), and for this band, the measured isolation is better than 40 dB. For the higher band, the measured isolation is more than 40 dB for 200 MHz (5.15–5.35 GHz) of bandwidth. The simulated radiation patterns of the antenna are well‐matched with the measured patterns at both the frequencies. [ABSTRACT FROM AUTHOR]