| Recently, broadband and high frequency communication systems put forward the development of miniaturized and wideband antennas, which are the key components of the communication systems. Therefore, research on the high-performance wideband antennas has become an urgent and significant topic, especially in the aspect of wideband high-efficiency millimeter-wave antenna arrays. Cavity-backed antennas(CBAs) as a good candidate have been widely reported in many papers, due to a lot of advantages, e.g., wide impedance bandwidth, high gain, stable radiation patterns and high aperture efficiency. In this paper, the CBA has been designed as an element in three kinds of millimeter-wave antenna arrays for three different applications.Firstly, one of the key problems of the CBA, i.e. the confliction between electrically large dimensions and applications to antenna arrays, is addressed by partially overlapping the cavity aperture without performance degradation. An 8-element E-plane linear CBA array and a 4 × 8 planar array are designed based on the proposed idea. Considering the loss of feeding network, they can achieve an impedance bandwidth of 79.3%(17.8-41.6 GHz) and 58.3%(23.3-40.8 GHz), a maximum realized gain of 19.8 and 24.4 d Bi, respectively.Secondly, an 8-element series-fed linear CBA array with fixed beams is proposed and investigated in this paper, and an overlapped cavity arrangement is also utilized. In order to eliminate the beam squinting caused by the conventional series feed network, an improved feed network with composite right/left handed transmission lines(CRLH TLs) is proposed. The simulated and measured results are presented to check the validity of this method. Then, the main beam of the proposed CBA array can be stably oriented in the direction(+30o) in a wide frequency band from 19 to 21 GHz, and the gain is from 11.6 to 13.8 dBi over the whole operating band.Finally, in order to reduce the loss and cost caused by the feed network, a novel three-element linear array based on a multi-port CBA is proposed in this paper. The multi-port CBA can function as an “antenna” for radiation as well as a three-way “power divider”. Then, a wide operating frequency band(19-21 GHz) of the proposed antenna array is achieved, the realized broadside gain is from 9.7 to 11.1 dBi, and the aperture efficiency ranges from 99.1% to 123.7%. The proposed array can be used as a subarray in low-cost large antenna arrays due to the simplified feed network. |
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