This letter presents a dual-polarized dielectric resonator antenna (DRA) achieving more than 40% fractional bandwidth, thus the 5G bands n257 and n260 are covered with a single antenna. Hence, the system cost is considerably reduced, since only one antenna array system is required. The bandwidth could be reached thanks to the wideband monopoles and differential feeding enabling hybrid operation in monopole and DRA mode. The antenna uses a standard two metal layer printed-circuit-board (PCB) process and 3-D printing for the fabrication of the dielectric resonators, reducing the number of PCB layers and the overall production cost. The prototypes of a single element and 2 × 2 array show a maximal gain of 7.1 and 10.4 dBi, respectively.
A broadband, miniaturised bow-tie antenna array element designed to be used in three-dimensional (3D) microwave imaging systems based on the tomographic approach is proposed. Miniaturisation is achieved by adding inductive strips to the capacitive antenna element and thereby lowering the cutoff operational frequency. Furthermore, the broadband directive radiation characteristic of the antenna with the proposed feeding network is equivalent to that of the same antenna being fed by an ideally symmetrical feeding network. This characteristic assists in the modelling of the antenna in the numerical solver. The proposed broadband antenna covering 0.85-3.25 GHz is a compact, directive element with a simple structure having the potential to be implemented in the numerical solver in 3D microwave tomography without imposing a high computational cost on the solver.
This letter presents a realization method of reconfigurable antenna systems based on smart materials. The reconfigurability is obtained by utilizing shape memory alloy directors. This realization method offers a longer lifetime and lower energy consumption than conventional approaches such as microelectromechanical systems (MEMS) or p-i-n diodes. As a proof-of-concept, a compact reconfigurable antenna for the 2.6-GHz Long Term Evolution (LTE) band was designed. The designed antenna is a quasi-Yagi antenna with its directors made from shape memory alloy. This antenna is made to be installed in a standard car-roof antenna housing. A prototype of the antenna presented here has been fabricated and measured.Index Terms-Automotive antenna, reconfigurable antenna, shape memory alloy (SMA), smart materials, Yagi.
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