A wideband circularly polarised array antenna consisting of 10-element bowtie dipole antenna and feed network is presented. A narrow patch connecting the pair of bowtie dipoles as an entity is employed to achieve high gain. To obtain wideband and flat-top beam of radiation patterns, amplitude and phase distribution along the feed are optimised by application of the Self-adaptive Differential Evolution algorithm. Particularly, the feed network with broadband phase shift performance is designed to satisfy bandwidth requirement ranging from 1.1 to 1.6 GHz. The proposed antenna can achieve an excellent impedance matching and Axial Ratio characteristics over the entire operating band. Moreover, the ripple of co-polarisation radiation pattern covering ±12°in the elevation plane is better than 0.92 dB; whereas the gain is also better than 11.8 dB and the side lobes are below −13 dB. Measured results validate the design concept and indicate that the proposed array exhibits good radiation characteristics.

An internal antenna for penta‐band wireless wide area network (WWAN 824–960/1710–2170 MHz) operation in the mobile handset is presented. By integrating two monopole slots with a monopole strip printed on the top portion of the main circuit board, the monopole slots generate their quarter‐wavelength slot modes for the antenna's lower band, whereas the monopole strip can contribute quarter‐wavelength resonant modes for the antenna's upper band. The monopole strip serves as a feed for the monopole slots and also functions as an efficient radiator. In this case, the antenna can provide two wide operating bands (795–1035/1700–2205 MHz) to cover the penta‐band WWAN operation.

A novel wideband circularly polarized (CP) antenna is presented in this article. The proposed antenna consists of a four-leaf clover patch, four L-probes, and wideband networks. Based on the tightly coupled mechanism, the four L-probes are formed as a ring with the adjacent ones kept close for strong mutual coupling. Consequently, the proposed antenna realizes a wideband impedance matching. Meanwhile, the fourleaf clover patch is put closely inside of the ring for further improving the impedance bandwidth, which is proximity-coupled fed by the four sequential-rotation L-probes with phase of 08, 908, 1808, and 2708. The four L-probes are connected to the respective ports of a wideband feeding network by a two-stage impedance transforming network. The measured results indicate that the proposed design has an impedance bandwidth of 66.7% from 1.0 to 2.0 GHz for VSWR 2 and a 3-dB axial ratio bandwidth of 56.5% from 1.08 to 1.93 GHz. Furthermore, in the operating bandwidth, stable and symmetry radiation patterns and high gain are obtained. The design has a 3-dB gain bandwidth of 38% from 1.3 to 1.9 GHz with a peak gain of 8.5 dBic.

A new design of a circularly polarised antenna based on the tightly coupled mechanism is presented. The proposed antenna consists of four tightly coupled dipoles, four impedance transforming networks and a wideband feeding network. Owing to the strong mutual coupling between coupled dipole elements, the proposed antenna realises a wide operating bandwidth. A prototype is manufactured and measured to validate the method. The measured results indicate that the proposed design provides a 10 dB return loss bandwidth of 101% (1.7-5.2 GHz) and a 3 dB axial ratio bandwidth of 77% (2.0-4.5 GHz). The design has a 3 dB gain bandwidth of 56% from 2.6 to 4.6 GHz with a peak gain of 10.4 dBic. Acceptable agreements can be obtained between the simulated and measured results.

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