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.
We have newly developed a W-band millimeter wave signal generator using an optical second-order harmonic generation technique for a LiNbO3 Mach-Zehnder optical intensity modulator. For generating the millimeter wave from 75 GHz to 110 GHz, our developed signal generation technique uses the signal generator from 18.75 GHz to 27.5 GHz, a microwave amplifier, the LiNbO3 Mach-Zehnder optical intensity modulator, and a photodiode. The system can generate the millimeter wave signal level of more than −30 dBm. We demonstrated antenna radiation pattern measurement for a standard gain horn antenna and an open-ended waveguide probe.
In this paper, the authors proposed an interference suppression method using space diversity of mobile terminal for a millimeter-wave full-duplex MIMO system. As a method of terminal-to-terminal interference suppression, a technique using Eigen-beamforming is studied. Further interference suppression is realized by applying the space diversity technique to the mobile terminal when performing Eigen-beamforming. The effectiveness of this method is confirmed by millimeter-wave radio propagation simulation using the ray-tracing method in an outdoor environment.
A polarisation insensitive transparent metasurface with two pass bands and two stop bands is proposed for 5G outdoor to indoor (O2I) coverage enhancement.Genetic Algorithm (GA) has been applied in order to provide the structural geometry of the unit cell for this metasurface.The proposed periodic structure consists of a unit cell design consisting of five stacked transparent patterned layers of Indium Tin Oxide (ITO) coated on Polyethylene Terephthalate (PET) substrates.The proposed transmission metasurface can be easily mounted on conventional glass windows to assist the O2I 4G/5G signals for the n7 and n78 of the 5G new radio (5G-NR), as well as shielding the 2.4/5 GHz WiFi signals from penetrating outside the building thereby enhancing the security.
This paper introduces a methodology to design a scheme enabling simultaneous near-field focusing and far-field radiation by using multiple lenses. A large-size lens is designed to convert the spherical wave emanating from the feed source to a quasi-plane wave. A small-size lens is located at a parallel plane away from the large-size lens. By imposing proper phase shifts on the small-size lens, it can capture part of the electromagnetic waves from the large-size lens to achieve a focal spot in the near-field region of the small-size lens. The gain of the radiation beam and the intensity of the focal spot can be controlled by either adjusting the area ratio of, or the separation between the large- and small-size lenses. The simulations validate the effectiveness of the proposed methodology. The proposed scheme offers an alternative solution to achieve simultaneous near-field focusing and far-field radiation.
In this paper, we present a novel non-contact distance measurement method using microwave reflection signals and artificial neural networks. Based on data learning, this method can effectively predict the distance of an object placed in a complex environment. In particular, by using a two-step neural network, we propose a method of maintaining precision while reducing the data used for training. Through an experimental test, microwave reflection signals for each distance are acquired and the two-step neural network is trained. Finally, the distance is estimated from the microwave reflection signal measured for an arbitrary distance. Using the proposed method, we have successfully demonstrated the distance measurement of an object placed in an underwater environment.
This paper presents transmission loss characteristics of a gap waveguide composed of a dielectric substrate with EBG elements. The proposed gap waveguide consists of a top conductor plate, a bottom dielectric substrate with mushroom-like EBG elements, and an air layer between them. EBG elements prevent a leakage from the gap waveguide in the air layer and can be manufactured cost-effectively with PCB processes. Transmission loss of the gap waveguide is analyzed by numerical simulation with ANSYS HFSS at 4.7 GHz. It reveals by the simulation that smaller transmission loss of the gap waveguide of less than 1 dB/m is obtained for the cases of a large distance of the EBG elements, a large width of the ridge conductor, and a small height of the air layer in comparison with a microstrip line with the same dielectric substrate.
This paper considers the impact of imperfect channel state information (CSI) on the array antenna layout design in massive multiple-input multiple-output applications. The analysis is based on channel estimation errors resulting from the least squares estimation algorithm in pure line-of-sight channels. We show that signal to interference-plus-noise ratio gains traditionally anticipated with irregular layouts, as compared to regular ones under the assumption of perfect CSI, vanish in case of CSI imperfections for the considered scenario.
This paper presents a dual-layer 180° hybrid coupler design with a wide operating bandwidth. The design can achieve a high isolation level between the sum and difference ports across a 30% bandwidth. The power division can be made equal or unequal between two ports by controlling the impedance of the shunted stubs and connected transmission lines. Based on the proposed hybrid couplers, the configurations of two multi-beam antenna feed networks, which can produce 6 and 12 beams, are synthesized. It is demonstrated that such multi-beam antenna feed networks can be built using only 180° hybrid couplers and phase shifters, and the proposed coupler design is an excellent candidate for building such networks with a wide bandwidth.
This paper presents a hybrid dual-polarized conformal dielectric resonator (DR) antenna (DRA) array for 5G millimeter wave mobile terminals. Each polarization has two resonant modes: the dielectric resonant mode and the slot mode. The combination of these resonant modes realizes wide impedance bandwidth (24.2-36.3 GHz) to cover 5G millimeter (a) wave band n257 (26.5-29.5 GHz), n258 (24.25-27.5 GHz), and n261 (27.5-28.35 GHz). Besides, due to the flexible three-dimensional (3D) structure of DRs, the proposed antenna array can be adapted into the form of a phone frame. Thus, the proposed antenna can be conformably placed in the frame of the mobile terminal. In this design, the curved glass in the frame of the mobile terminal also works as an inherent portion of the DR. Therefore, the glass cover will not place a negative effect on the proposed antenna array as in conventional design approaches.
This paper presents a frequency selective surface design and simulation using intertwined triangular structures.It has been discovered that by using the proposed tessellated intertwined lattice, the reduction of the resonance frequency of a frequency selective surface can be improved by 22.58% compared with other triangular structures.Additionally, this structure is used as a MEFSS to improve the miniaturization of the structure and obtain a compact, angular stable band-pass filter.The simulations presented in this paper have been obtained using CST Microwave Studio.
In this article, we presents a high gain low profile and compact dual band with independent phase control transmitarray unit cell in Ku-band. Independent phase shift and polarization control antenna array develops for many communication applications like satellite communication, mobile communication and SATCOM on the move etc. A dual band independent phase control transmitarray (DIPCTA) develops at 12.5/16.5 GHz with dual linear polarization. There are two pin diode (active) loaded patches are composed to control the uplink and down link frequency bands. Two parasitic off set feed patches place over Receiver (Rx) side to transmit energy through Vias to Transmitter (Tx) side. There are four states available for insertion losses and phase distribution control for each upper band and lower band frequency. Upper band achieved min theoretical insertion losses 0.74 dB approximately. Lower band theoretical minimum insertion losses obtain 1.34 approximately due to four-pin diode at same side. 180-degree phase shift achieve for upper and lower band control states independently.
This communication presents a continuous transverse stub (CTS) array with a gain larger than 38.5 dBi at K/Ka band (17 GHz-31 GHz) for SatCom applications. The CTS array is fabricated in printed circuit board technology (PCB) with a stack-up of 15 layers without any buried and blind vias by resorting to a novel contact-less transition among layers. A very-broadband quasi-optical beamformer made by a pillbox coupler is used as a feeder. Such a coupler is optimized to cover the K/Ka band. A ±65° beam steering angle in elevation is obtained. The steering is achieved through a mechanically moving horn placed in the focal planer of the pillbox coupler. The antenna’s aperture is a square with $62.2\lambda_{0}$ side length and a thickness of approximately $6\lambda_{0}$, where $\lambda_{0}$ is the free space wavelength at 31 GHz.
Accurate and precise measurement of the scattering parameters of a material under test (MUT) is essential for enhancing the measurement uncertainty of material parameter measurement of the MUT. Two one-port calibration methods applicable to a free-space one-port material measurement are described, and their measurement results are compared with those obtained from the two-port TRL method for a glass plate in W-band.
In this paper, a V-shaped wire antenna periodically loaded with lumped capacitors to construct zeroth-order resonators is proposed for wideband operation. The numerical simulation results show the operating band for a reflection loss below -10.0 dB ranging from 2.89 GHz to 5.99 GHz, and the fractional bandwidth of 69.9% is achieved.
This paper presents a switched beam-forming network (SBFN) integrated with a power divider for 5G applications. The proposed design consists of a metamaterial-based $4 \times4$ butler matrix (BM) and $1 \times2$ Wilkinson power (WPD) divider. The simulated results show that the proposed design achieved an outstanding insertion-loss of $-9 \pm 1$ dB and excellent reflection coefficient between the frequency range of 3.2GHz – 3.7GHz. The simulated phase differences achieved between the output ports are $-45^{\circ} \pm 8^{\circ}$ for the excitation of Input Port-1. The proposed design is suited for a 5G switched-beam antenna array (SAA) because of its enhanced bandwidth and compact structure of BM and WPD.
