A novel quasi-Yagi antenna is proposed for millimeter-wave (mmWave) 5G cellular handsets operating in the 28-GHz band. The proposed antenna is designed to be compact through modification of the planar folded dipole topology so that it can be mounted inside a compact mobile terminal. A vertically stacked structure utilizing a multi-layer printed circuit board (PCB) and via holes is applied to the antenna topology to minimize the antenna lateral width while maintaining the characteristics of the planar folded dipole antenna. A single antenna yields a -10-dB bandwidth for a return loss of 12.3 % (26.3 to 29.75 GHz) and a gain of 5.51 dBi at 28 GHz. The change in beam patterns due to the chassis effect when 4-element linear arrays are inserted into the upper and side edge inside the terminal is analyzed.

This paper proposes a pattern reconfigurable high gain spherical dielectric resonator antenna (DRA) operating on higher-order mode. Two microstrip patches were used to excite TE301 mode in the different direction. A reconfigurable switch network was designed and it has three switching modes for selecting each patch alone or selecting them simultaneously. The proposed antenna can reconfigure its radiation pattern by using a feeding structure which is consist of two microstrip patches and the reconfigurable switch network. A prototype antenna operating on TE301 mode at 5.8GHz was fabricated by ceramic material. By experiment, we validated the new concept of pattern reconfigurable spherical DRA.

This paper presents the novel design techniques for terahertz (THz) antenna-in-package (AiP) to overcome issues resulting from multilayer PCB-based antenna array integration, fabrication, and measurement. We propose a wideband dual-polarized stub-loaded proximity-coupled stacked patch antenna and vertical power divider as design solutions. Circuit analysis is performed to provide the equivalent circuit model and its design validity. We designed, simulated, and measured a 4×1 subarray, which ultimately builds THz 8×8 AiP for the next generation 6G communications system. The designed proximity-coupled stacked patch antenna employs open and short stubs in via transition of the antenna’s feeding for bandwidth enhancement. The designed power divider is constructed vertically to minimize the size of the 4×1 subarray. This innovative power-splitting architecture significantly decreases the complexity of the feeding network because the divider is designed without conventional T-junctions and quarter wavelength impedance transformers. Thus, the size of the dual-fed dual-polarized 4×1 subarray, limited by two 4-way power dividers can be shrunken considerably. Based on these proposed techniques, we fabricated and measured an 8×8 antenna array package on our custom-built probe station. The measured boresight gain of the 8×8 antenna array package exceeds 17.1 dBi within the operating bandwidth of 136 to 148 GHz.

This paper presents a wide-angle scanning phased array antenna using high gain pattern reconfigurable antenna (PRA) elements. Using PRA elements is an attractive solution for wide-angle scanning phased array antennas because the scanning range can be divided into several subspaces. To achieve the desired scanning performance, some characteristics of the PRA element such as the number of switching modes, tilt angle, and maximum half-power beamwidth (HPBW) are required. We analyzed the required characteristics of the PRA element according to the target scanning range and element spacing, and presented a PRA element design guideline for phased array antennas. In accordance with the guideline, the scanning range was set as ±70° and a high gain PRA element with three reconfigurable patterns was used to compose an 8x1 array antenna with 0.9 λ₀ spacing. After analyzing whether the active element patterns meet the guideline, the array antenna was fabricated and measured to demonstrate the scanning performance. The fabricated array can scan its beam from -70° to 70° by dividing the scanning range into three subspaces. It shows that even if the array antenna has large element spacing, the desired scanning performance can be obtained using the elements designed under the guideline.

This paper proposes a millimeter-wave series-fed coupled split-ring resonator array (SCSRRA) antenna with a wide fan-beam pattern and low sidelobe level (SLL) for automotive radar. The proposed array antenna has the advantages of low cost, low profile, and low manufacturing difficulty. The proposed array antenna uses a split-ring resonator as a radiating element coupled from a microstrip line. The split-ring resonator has the advantage of suppressing cross-polarization due to feed phase errors. To reduce the surface wave through the ground edges and enhance the beamwidth, we added the mushroom-shaped electromagnetic bandgap (EBG) structure. Amplitude tapering to reduce the SLL was implemented by adjusting the distance between each element and the microstrip line. The prototype SCSRRA antennas operating at 79 GHz were fabricated, and the characteristics of the wide fan-beam pattern and low SLL were experimentally verified.

A highly efficient antenna array for unmanned aerial vehicle (UAV) mounted radar applications with a tilted-beam characteristic and a 360° beam coverage is proposed in this paper. The proposed array antenna is configured by four planar super J-pole antennas with 2-dimensional ground reflectors. Each super J-pole antenna element provides a high directivity where the peak gain is tilted about 45° facing toward the ground from the bottom of a UAV body. Thus, the air-to-ground communication difficulty due to the altitude difference between the UAV and ground targets can be effectively solved. Further, the four super J-pole elements with a switched operation can cover the whole 360° areas around the UAV while high antenna gain is maintained. To verify the performance, the proposed structure was implemented at 5.9 GHz with an overall volume of 0.88 × 0.88 × 0.83 λ_o³. The measured 10-dB impedance bandwidths for all four antenna elements were better than 27.2% and the isolation among the four antenna ports was also always better than 13 dB. The measured peak gain was better than 7.4 dBi and tilted at 45° in the elevation angle. Lastly, the measured half power beam widths in elevation and azimuth planes were more than 60° and 87°, respectively.