Zhaoyang Tang

Wideband, Low-Profile, Dual-Polarized Slot Antenna with an AMC Surface for Wireless Communications

A wideband dual-polarized slot antenna loaded with artificial magnetic conductor (AMC) is proposed for WLAN/WIMAX and LTE applications. The slot antenna mainly consists of two pairs of arrow-shaped slots along the diagonals of the square patch. Stepped microstrip feedlines are placed orthogonally to excite the horizontal and vertical polarizations of the antenna. To realize unidirectional radiation and low profile, an AMC surface composed of 7 × 7 unit cells is designed underneath a distance of ( being the wavelength in free space at 2.25 GHz) from the slot antenna. Both the dual-polarized slot antenna and the AMC surface are fabricated and measured. Experimental results demonstrate that the proposed antenna achieves for both polarizations a wide impedance bandwidth (return loss 10 dB) of 36.7%, operating from 1.96 to 2.84 GHz. The isolation between the two input ports keeps higher than 29 dB whereas the cross-polarization levels basically maintain lower than −30 dB across the entire frequency band. High front-to-back ratios better than 22 dB and a stable gain higher than 8 dBi are obtained over the whole band.

Single-Feed Wideband Circularly Polarized Crossed Dipole Antenna with Bent-Slot Loading

ABSTRACT A novel single-feed crossed dipole antenna with bent-slot loading is proposed for broadband and unidirectional circular polarization operations. This antenna, with a simple structure, is composed of two orthogonal dipoles with kite-shaped arms. To achieve broadband circularly polarized characteristic, two capacitive bent slots are loaded into one pair of crossed dipole arms to realize a 90° phase difference between the dipoles. Moreover, a modified coupling feeding technique is employed to increase the impedance bandwidth. Experimental results show the proposed antenna has a 10-dB impedance bandwidth of 62.6% (1.47–2.81 GHz) and a 3-dB axial ratio bandwidth of 37.0% (1.85–2.69 GHz). Besides symmetrical radiation patterns, desirable antenna gains around 9 dBic over the wide operating bandwidth are also demonstrated.

Wideband Planar Inverted-F MIMO Antenna with High Isolation

A wideband planar inverted-F MIMO antenna with high isolation is proposed in this letter. The proposed MIMO antenna consists of two back-to-back planar inverted-F antennas and a fork- shaped decoupling stub. The two planar inverted-F antennas are merged together with a shorting strip connected to the ground plane. In order to enhance the isolation, a fork-shaped decoupling stub connected to the ground plane through shorting pins is introduced, and the impedance matching is significantly improved simultaneously. The proposed antenna prototype is fabricated and measured, and a compact size of 28 × 26 mm 2 makes the proposed antenna be easily integrated in a MIMO system. Measured results show that the measured bandwidth for |S11| less than −10 dB covers from 5.05 GHz to 6.23 GHz, and the measured isolation is higher than 20 dB in the whole working frequency band.