A novel CPW-fed broadband circularly polarised square slot antenna is proposed and fabricated. The proposed antenna is fed by a CPW with a widened L-type strip along the diagonal line of the square slot. Measured results show that the 3 dB axial-ratio bandwidth of the proposed antenna can reach 17%. The proposed antenna has simple coplanar geometry which can be easily fabricated on inexpensive substrate.

A folded slot with open end is introduced to achieve a dual-band coplanar waveguide (CPW)-fed monopole antenna for radio frequency identification (RFID) applications. The designed antenna, which, including the substrate, is only 32 mm in height and 20 mm in width, can operate simultaneously at the 2.45 and 5.8 GHz bands with -1.8 and 2.3 dBi gains, respectively. Its properties make the antenna suitable for RFID tags.

A novel reconfigurable coplanar waveguide (CPW)-fed square slot antenna with switchable polarization is presented. The proposed antenna is fed by a CPW, with two T-shaped metal strips connected to ground plane using pin-diodes. Switching between right-hand circular polarization (RHCP) and left-hand circular polarization (LHCP) is achieved by turning the pin-diodes on or off. The designed antenna is implemented and measured. It shows that the proposed antenna has broad CP bandwidth in both RHCP and LHCP states.

A new method to improve the gain of patch antenna with metamaterial composed of ring aperture lattice is presented. The influences of the number of metamaterial layers and a comparison of electromagnetic characteristics between the conventional patch antenna and the new metamaterial patch antenna are studied by using numerical simulation method. Then, a patch antenna with the metamaterial is fabricated and measured. The simulation and experimental results show that this method is effective and this structure can realize congregating the radiation energy, thus the gain of the antenna with metamaterial can greatly increase when compared with the conventional one.

A novel small CPW-fed T-shaped antenna for MIMO application is presented. The size of the antenna is only 35% of that of conventional CPW-fed T-shaped antenna, which has satisfied return loss bandwidth and omnidirectional radiation characteristics. A multifeed 8-element planar array is fabricated and measured. It shows that the features of small size, uniplanar structure, good radiation characteristics and small mutual coupling are promising for MIMO applications in compact portable devices.