A 42 element microstrip parasitic patch antenna is developed in the millimeter-wave band for 5th Generation (5G) mobile communication base stations. A metalized elliptical stripline to embedded microstrip transition with adaptive via hole arrangement as well as a 20dB Chebyshev tapered 6 way power divider is proposed to have an insertion loss of 0.045 dB. To confirm the feasibility of the antenna, the antenna has been measured to provide a 6.2 % impedance bandwidth from 26.83 GHz to 28.56 GHz at VSWR of less than 1.96 dB. The array antenna gains of more than 21.4 dBi has been realized with side lobe levels (SLLs) of less than -19.4 dB operating within 27.5 GHz to 28.5 GHz in both the azimuth and elevation directions.

A novel low-cost, high-gain mmWave antenna has been presented. The antenna is a 6 x 5 proximity-coupled planar array suitable for 5G cellular applications. Good agreement between simulated and measured results achieved shows that the proposed antenna structure is efficient in achieving broadband characteristics and low sidelobe levels with conformal size. The antenna has a gain of 21 dB over a bandwidth of 27.5 GHz to 28.5 GHz. It also exhibits an impedance bandwidth of 9.8% from 26.04 GHz $\times$ 28.78 GHz.

This paper presents a novel wideband microstrip comb-line linear array antenna using end feeding developed in the millimeter-wave. The proposed antenna is designed for 28 GHz and has 12 elements. The reflection-canceling slit structure technique is adopted to develop a broadside beam with low reflections at the input. The proposed array is designed using stub-studded radiating elements that create more resonances to broaden the impedance bandwidth. The structure is a novel comb-line linear array antenna with stub-studded radiating elements and was developed by applying stubs to eight of the radiating elements of the array to increase the input impedance bandwidth. This helps to attain a wideband linear array antenna on a single dielectric substrate, which conventionally has a narrow bandwidth. The input impedance bandwidth is from 23.5 to 33.11 GHz, which is equivalent to a bandwidth of 33.95%. The radiation pattern bandwidth is from 27.5 to 29.25 GHz for sidelobe levels of below -20 dB equivalent to a bandwidth of 6.167%. The proposed antenna array presents features such as a simple structure with low fabrication cost and an enhanced impedance bandwidth with high sidelobe suppression. The feasibility of the proposed antenna array was evaluated by simulation and measurement in the millimeter-wave band.

In this communication, a compact log-periodic dipole array (LPDA) antenna is developed at 0.5 – 10 GHz. This LPDA structure constitutes fewer dipole elements than a conventional LPDA antenna that exhibits similar resonant frequencies. In the design of a miniaturized LPDA antenna, various size-reduction techniques have been proposed in the open literature to decrease the lateral size of a conventional LPDA. However, little or no attention has been focused on reducing the size of the LPDA antenna by shortening the boom or axial length. In pursuit of reducing the total length of a conventional LPDA, a dual-band dipole antenna is proposed as the radiating elements for the LPDA antenna in this communication. The proposed dipole structure is a printed half-wave principal dipole loaded with a pair of resistive structures via sub feeding-lines. The pair of resistive loads forms the auxiliary (secondary) dipole of the proposed dipole antenna. The structure of the proposed dual-band dipole is achieved without a ground plane as opposed to many existing dual-band antenna types. As a result, the dipole antenna has a simple geometry with omnidirectional characteristics. Also, the feeding structure of this dipole can provide extra degree of freedom to tune the antenna for matching purposes. A 25-element LPDA antenna is designed with a much reduced boom length as compared with existing LPDA structures. To confirm the feasibility of the technique, the experimental results of the proposed LPDA prototype were analyzed and juxtaposed with a benchmark LPDA.

A compact planar log‐periodic dipole array (LPDA) antenna operating from 0.55 to 9GHz with high measured gain is proposed to be implemented in a reverberation chamber as a source antenna. To minimise the total size of the LPDA antenna, variants of top‐loading techniques are utilised, and a much smaller spacing factor is opted to specify the spacing between the elements. However, miniaturisation of the LPDA antenna limits the antenna's wideband characteristics over the desired range of frequencies. Hence, a feedline meander and a trapezoidal stub are incorporated into the design as impedance matching techniques to effectively enhance the bandwidth performance especially for the lower band of the antenna's operating frequency range. The LPDA antenna exhibits radiation patterns with and without a radome having the measured gain ranging from 2.48 to 7.89 dBi and from −1.20 to 7.94 dBi, respectively.

The power transfer efficiency (PTE) is a crucial aspect for effective wireless power transfer (WPT) applications. The quality factor (Q) of the WPT coil plays a critical role in ensuring higher PTE. In this paper, a novel method of improving the Q of a WPT coil is proposed. Resistance reduction techniques are presented which involves variation of the trace pitch, width, and thickness. This approach targets the high AC losses centered in the inner turns, which subsequently results in an increased Q. Numerical analysis with respect to the inductance and resistance models are presented, analyzed, and compared to that of the EM simulation results. To verify the efficacy of the proposed coil structure, a prototype is fabricated where good agreement is achieved between the measured and simulated results. The proposed coil attained a quality factor increment of about 19.24% at 85 kHz in comparison to the conventional one. The proposed technique can be used to optimize planar spiral coils to attain higher Q.