This letter introduces a novel transparent single-layer frequency-selective surface (FSS) design on conventional window glass, which aimed at achieving signal selectivity for 5G millimeter-wave communication (n257; 26.5–29.5 GHz). The unit cell of the FSS layer features a structure formed by square loops and spirals, using small-width metal lines (200 and 250 μm). Additionally, a new approach is presented to enhance the transmission characteristics of the FSS layer by integrating a transparent dielectric slab while maintaining good optical transparency (>60%) in the visible light spectrum. The measurement results validate both the theoretical predictions and the design procedure, confirming the feasibility and transparency for signal filtering on window glass at millimeter waves. These findings hold promising potential for optimizing 5G wireless communication systems and simplifying signal filtering applications.

A high-gain millimeter-wave patch array antenna is presented for unmanned aerial vehicles (UAVs). For the large-scale patch array antenna, microstrip lines and higher-mode surface wave radiations contribute enormously to the antenna loss, especially at the millimeter-wave band. Here, the element of a large patch array antenna is implemented with a substrate integrated waveguide (SIW) cavity-backed patch fed by the aperture-coupled feeding (ACF) structure. However, in this case, a large coupling aperture is used to create strongly bound waves, which maximizes the coupling level between the patch and the feedline. This approach helps to improve antenna gain, but at the same time leads to a significant level of back radiation due to the microstrip feedline and unwanted surface-wave radiation, especially for the large patch arrays. Using the SIW cavity-backed patch and stripline feedline of the ACF in the element design, therefore, provides a solution to this problem. Thus, a full-corporate feed 32 × 32 array antenna achieves realized gain of 30.71–32.8 dBi with radiation efficiency above 52% within the operational band of 25.43–26.91 GHz. The fabricated antenna also retains being lightweight, which is desirable for UAVs, because it has no metal plate at the backside to support the antenna.

This letter details the design of a compact pattern reconfigurable antenna that is based on the analysis of a tunable gap-incorporated band-stop frequency selective surface (FSS) unit cell. By changing the state of the RF PIN diode, the proposed FSS unit cell can demonstrate either a dipole-resonance mode or a circulating-current mode, thus allowing it to behave as a reflective or transparent structure, respectively, around the same frequency. A simple pattern reconfigurable antenna with reduced active switching elements for omnidirectional and directional beam-steering that is created by utilizing the proposed FSS unit cell can fulfill the desired function while avoiding the complexities involved in employing large FSS arrays. A prototype of the proposed antenna is fabricated and measured, and it shows a return loss |S11| < –10 dB from 1.7 – 1.8 GHz along with a peak gain of 6.8 dBi. Ultimately, this proposed antenna is expected to be applicable in various wireless communication systems.

In this Letter, a high‐gain sub‐terahertz lens horn antenna with a metal guide is proposed. In this antenna, high gain is achieved by using a metal guide and dielectric lens. The experimental results show that the impedance bandwidth of the proposed antenna is above 200 GHz, and the measured peak gain of the antenna is 39 dBi at 240 GHz.

This paper presents a substrate-integrated waveguide (SIW)-fed magneto-electric dipole antenna comprising an inclined bridge-connected radiator based on aluminum posts for millimeter-wave broadband applications. The proposed structure creates additional resonant frequencies for the electric and magnetic dipoles by bridging the two metal posts and adjusting their inclination angles, thereby improving the impedance bandwidth. Additionally, it also improves the flatness of the gain while maintaining the maximum realized gain. The impedance bandwidth of S11<–10 dB in the single element is 36.2% with a maximum gain of 9.1 dBi, and the 3 dB gain bandwidth exceeds 40%. Furthermore, an efficient pattern-based matching technique is developed in the array design to mitigate the effect of the bonding film that combines two different SIW layers. The proposed 8 × 8 array antenna demonstrates a measured impedance bandwidth of 25.2% from 33.6 GHz to 43.3 GHz with a maximum gain of 26.2 dBi at 42.5 GHz.

Dual polarised antenna with high isolation for small base‐station applications is proposed. The proposed antenna is composed of two metallic trapezoidal dipole elements, two metallic feed plates, a dielectric substrate, a metallic cube and a radome. The measured −10 dB impedance bandwidth is 2.4 GHz to 2.8 GHz in Port‐1 and 2.5 GHz to 3 GHz in Port‐2. The proposed antenna has an isolation of >45 dB at the centre frequency. The measured average antenna gain is 7.5 dBi, and the cross polarisations are all <30 dB below the co‐polarisation value.