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This letter presents a compact dual-band dual-polarized loop-slot planar antenna. The antenna consists of a rectangular loop, a coplanar waveguide (CPW), and a microstrip line. The dual-band characteristic is realized using two different type resonant modes of the loop-slot antenna, namely, a loop basic mode in the lower band and a slot basic mode in the higher band. A CPW is used to excite vertical polarization modes and a microstrip line is used to excite horizontal polarization modes to achieve dual-polarized performance. The overall dimension of the prototype is only 2 57 55 mm . The proposed antenna is built and tested. It has two common -10dB impedance bandwidths of 420MHz (2.34-2.76GHz) and 660MHz (3.22-3.88GHz) to cover 2.4GHz WLAN band and 2.5/3.5 GHz WiMAX bands, respectively, and the isolation between the two ports is better than 21dB in the dual-band. The antenna has stable radiation patterns and gains in both bands. The antenna also has the merits of compact dimension, low cross-polarization, and low cost.

A novel planar monopole antenna with dual‐band circularly polarisation (CP) is presented here. The antenna consists of a modified L‐shaped monopole, an inverted‐L strip, and a modified ground. The utilisation of the modified L‐shaped monopole not only generates dual‐band operation, but also excites CP radiation in the lower band. In order to achieve CP in the upper band, a parasitic inverted‐L strip is added on the top plane of the substrate and a modified ground is designed. The proposed antenna has been fabricated and tested, the measured −10 dB reflection coefficient bandwidths are 370 MHz (2.38–2.85 GHz) in the lower band and 2330 MHz (4.05–6.38 GHz) in the upper band. The measured corresponding 3 dB axial ratio (AR) bandwidths are 610 MHz (2.39–3 GHz) and 850 MHz (5.15–6 GHz), respectively. The overlapped −10 dB reflection coefficient and AR bandwidths can totally cover the WLAN bands, Wi‐Fi bands, Bluetooth band, and partly cover the WiMAX bands. The proposed antenna owns bidirectional radiation characteristic and reasonable gain at both the lower band and the upper band.

Meander lines (MLs) in two configurations are presented to reduce the mutual coupling (MC) between two microstrip patch antenna elements. Inserting a slot in the ground plane between the antenna elements is a simple method to reduce the MC, while adding the MLs in the slot of the ground can further reduce the MC. In the first configuration, one ML is inserted in the slot of the ground and a maximum MC reduction of 39 dB throughout the −10 dB bandwidth is achieved. What’s more, the radiation patterns are not changed compared with the dual-element microstrip antenna array with a slotted ground. For the second configuration, two MLs are added in the slot of the ground. It is found that a maximum isolation of 53 dB can be obtained. However, the radiation patterns are slightly changed compared with the dual-element microstrip antenna array with a slot in the ground. Meanwhile, the measured peak gain and efficiency of the dual-element microstrip antenna array in the two configurations are given. Along with this paper, several prototypes have been fabricated and measured. The simulated results are in good accordance with the measurements, which are presented to verify that MC reduction can be achieved between microstrip antenna elements by adding the MLs in the slotted ground.

This article presents a miniaturized ultra-wideband planar monopole antenna with an oval radiator. The proposed antenna is fed by a coplanar waveguide (CPW), and two L-shaped stubs are extended from the ground plane of the CPW. This presented antenna is able to produce resonances in the lower frequency band and realize better impedance matching performance in the middle and higher frequency bands with the aid of the L-shaped stubs. The antenna was built and tested. The total size of the proposed antenna is only 26 × 20 × 1.6 mm 3 . Its measured -10 dB impedance bandwidth is 10.1 GHz (3.1-13.2 GHz). The measured far-field radiation patterns are stable in the whole operating frequency band.