Reconfigurable Intelligent Surfaces (RIS) have been identified as a potential ingredient to enhance the performance of contemporary wireless communication and sensing systems. Yet, most of the existing devices are either costly or not available for reproduction. To close this gap, a Reconfigurable Intelligent Surface for the frequency range of 5 GHz WiFi is presented in this work. We describe the designed unit cell, which is optimized for the full frequency range of 5.15 to 5.875 GHz. Standard FR4 substrate is used for cost optimization. The measured reflection coefficient of a rectangular RIS prototype with 256 elements is used for RF performance evaluation. Fabrication data and firmware source code are made open source, which makes RIS more available in real measurement setups.
A dual-wideband dual-polarized antenna array is proposed for millimeter-wave systems. Dual bands and dual polarizations are supported by two layers of gridded patches and wideband feeding structures. A 2× 2 array is composed for beam scanning. High isolations and stable radiations are achieved by several groups of fences in the array. A prototype is fabricated and measured to validate the design. The bandwidth is 23.65-31.05 GHz and 41.85-46.00 GHz for both polarizations with isolations better than 19.8 dB. Meanwhile, the average gains achieve 12.1 dBi for the lower band and 11.2 dBi for the higher band, providing a scanning range from -33° to 31° and -22° to 21°.
This paper presents a novel wideband filtering power divider based on a multi-mode dielectric-loaded cylindrical cavity resonator. The resonator is constructed by a metal-embedded cylindrical dielectric disk loaded at the center of a cylindrical cavity, and fed by three probes with 120 -degrees displacement with each other. Three resonant modes (TM010, TE111 e, TE111 o) can be gathered for operation by properly tuning the lengths of feeding probes and the radius of the dielectric disk. Two transmission zeros can be respectively generated at the upper and lower stopband. For demonstration, a prototype operating at 3.5 GHz was designed, fabricated, and measured. A good agreement between the simulation and measurement can be observed. The measured results suggest a wide fractional bandwidth of 33.3%.
In this paper, we evaluate the effect of raindrops on the on-glass antennas in order to make the design more efficient. Automotive glass has a three-layer structure with an interlayer film in between to prevent shattering. A dipole antenna was placed on the lower center surface of a 300 mm $\times300$ mm glass sheet, and the electromagnetic field analysis was conducted using a model in which raindrops adhered to the antenna. The results show that raindrops have little effect on the reflection coefficient of the antenna. However, if the raindrops flow in the same direction as the antenna and form streaks, the reflection coefficient worsens. Both raindrops and rain streaks were found to affect the radiation pattern.
This paper describes the design of a generalized Luneburg lens antenna that can scan $360^{\mathrm{o}}$ in azimuth. The full azimuth scanning is achieved by deploying two identically stacked lenses and 3 dB90o hybrid couplers. The antenna operates in the n260 band, from 37-40GHz. Simulation results of the integrated antenna system are presented illustrating that the antenna can scan $360^{\mathrm{o}}$ in the azimuth plane.
