Miniaturised wideband filtering antenna by employing CRLH-TL and simplified feeding structure

A miniaturised three-order wideband filtering antenna by employing a composite right/left handed transmission line (CRLH-TL) and a simplified asymmetric coplanar strip feeding structure is presented. The CRLH-TL resonator resonates at zeroth-order mode and first-positive-order mode, and the meander-line antenna performs not only as a radiator but also as the last resonator of the corresponding bandpass filter. The proposed filtering antenna has four poles in the passband and two radiation nulls at the band edges. Compared with conventional antennas, the proposed filtering antenna shows flat gain responses and flat radiated powers within the passband, and displays good frequency skirt selectivity. Measurement results show that the filtering antenna can operate at from 4.03- to 7.11 GHz, has a 3.08 GHz bandwidth, a 2.5 dBi average gain in the broadside (+Z) direction and nearly 30 dBm average radiated power within the passband.