Millimeter-wave Wireless Communication Systems Research Articles

Measurement and Analysis of Propagation Mechanisms at 40 GHz: Viability of Site Shielding Forced by Obstacles

Mitigation of interference among adjacent radio systems is a topic of growing interest as the spectrum occupation increases. Site-shielding techniques appear as a method of improving millimeter-wave wireless communication system design, allowing frequency reuse and reducing cochannel interference. The viability of applying such techniques to systems operating in frequency bands around 40 GHz is the aim of this paper. Several propagation mechanisms are experimentally studied, including transmission across building obstacles, depolarization, reflection, and diffraction. The performance of some theoretical models of the different scattering mechanisms has been compared with measurement results. The measuring and processing procedures have also been improved. Values of the dielectric parameters of the materials in this frequency band have been obtained and are given in this paper. The attenuation results indicate that various materials, such as mortar, brick, and concrete walls, that present large values of attenuation in decibels per centimeter, can be used to shield base stations, reducing the frequency reuse distance in radio cellular networks. It can also be concluded that there is a significant diffracted field in the shadow region of brick corners.

Wideband 3/4 Elliptical Ring Patch for Millimeter-Wave Communication

In this study, a wideband 3/4 elliptical ring patch operating millimeter wave band is proposed. Using this structure, the patch antenna is designed for circular polarization and wide-band operation at about 32.1-40 GHz for millimeter wave communication. Simulated and measured results for main parameters such as voltage standing wave ratio (VSWR), impedance bandwidth, axial ratio, radiation patterns and gains are also discussed. The study shows that modeling of such antennas, with simplicity in designing and feeding, can well meet the requirements of millimeter-wave wireless communication systems.

A W-Band Linear Tapered Slot Antenna on Rectangular-Grooved Silicon Substrate

A W-band (75-110 GHz) coplanar-waveguide (CPW)-fed linear tapered slot antenna (LTSA) on rectangular-grooved silicon substrate is presented. Compared to its ungrooved version, the W-band CPW-fed LTSA shows significantly improved endfire radiation patterns in the whole band. Also, the symmetric patterns together with moderately high gain (8-10 dBi), high front-to-back (F/B) ratio (16-28 dB), and low sidelobe level (SLL; -15 to -17 dB for the E-plane and -11 to -18 dB for the if-plane) are achieved. The proposed CPW-fed LTSA is expected to find applications, such as a transceiver antenna in millimeter-wave wireless communication systems, owing to its easy integration with the uniplanar monolithic millimeter-wave integrated circuits

V-Band Multiport Heterodyne Receiver for High-Speed Communication Systems

A V-band receiver using a MHMIC multiport circuit is presented in this paper. The millimeterwave frequency conversion is performed using a passive circuit, the multiport, and related power detectors, avoiding the conventional millimeter-wave active costly mixers. Basically, the multiport circuit is an additive mixer in which the resulting sum of millimeter-wave signals is nonlinearly processed using millimeter-wave power detectors. This multiport heterodyne receiver is an excellent candidate for the future low-cost high-speed millimeter-wave wireless communication systems. The operating principle of the proposed heterodyne receiver and demodulation results of high-speed MPSK/QAM signals are presented and discussed in this paper. According to suggested datarate of 100-400 Mbps used to prove the operating principle, the IF of this receiver was chosen at 900 MHz. Therefore, this receiver is a possible alternative solution for WPAN applications

Q-band high conversion gain active sub-harmonic mixer

Abstract In this paper, we have designed and fabricated high conversion gain Q-band active sub-harmonic mixers for a receiver of millimeter-wave wireless communication systems. The fabricated active sub-harmonic mixer used second harmonic signals of a low local oscillator (LO) frequency. The fabricated mixer were successfully integrated by using a 0.1 μm GaAs pseudomorphic HEMT’s and a coplanar waveguide structure. We showed that the highest conversion gain of 4.8 dB has obtained at a LO frequency of 17.5 GHz and a RF frequency of 40 GHz. Conversion gain from the fabricated sub-harmonic mixer is one of the best reported thus far. The active sub-harmonic mixer also ensure a high degree of isolations, which are −35.8 dB from LO-to-IF and −40.5 dB from LO-to-RF, respectively, at a LO frequency of 17.5 GHz.

Design of Reconfigurable Millimeter-Wave Patch Antenna

Reconfigurable antenna is a novel concept of antenna. A novel reconfigurable millimeter-wave patch antenna is proposed and simulated by the finite-difference time-domain (FDTD) method. The simulation results demonstrate that the antenna can operate in two states and shift the operation frequency band between 22.8∼30.8GHz and 28.7∼37.3GHz as the state is changed. This antenna is useful for millimeter-wave wireless communication and radar systems.

Constant flux illumination of square cells for millimeter-wave wireless communications

The use of highly shaped-beam base-station antennas in millimeter-wave wireless communication systems may contribute to significantly enhance system performance. Previously proposed axial symmetric dielectric lenses provide a most useful constant-flux circular footprint, but they may fail to cover the regions near the vertices of square or rectangular cells, unless excessive wall illumination is allowed. This paper presents a simplified procedure to design shaped three-dimensional dielectric lenses that produce constant-flux illumination with square or rectangular footprints, suitable for indoor cells. The procedure is based on circular symmetric dielectric-lens design formulation, yet very sharp rectangular-cell boundary is obtained. Calculated and measured antenna performance is presented, not only in terms of radiation pattern, but also in terms of coverage and time-dispersion characteristic. The procedure is demonstrated for a square-cell lens and is extended for the rectangular-cell case.

A broadband and miniaturized V-band PHEMT frequency doubler

We present the design and measured performances of a V-band frequency doubler fabricated using 0.15 μm GaAs pseudomorphic HEMTs and the three-dimensional (3-D) MMIC technology. Thank to the use of an improved 180/spl deg/ rat-race hybrid, the frequency doubler exhibits high spectral purity over a large bandwidth. Isolation better than 30 dB is achieved on a frequency range from 31.736 GHz and fundamental frequency rejection better than 35 dB is achieved between 31.5 GHz and 37.5 GHz. Conversion loss measured at 32.5 GHz is 8.5 dB for an input power of 14 dBm. Both the broadband spectral purity and the small size of 1 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> make it suitable for the realization of high-quality and widely tunable V-band frequency sources. For the future developments of millimeter-wave wireless communication systems, it offers good perspectives toward the fabrication of single-chip V-band transceiver including the frequency source.

Measurements and models for 38-GHz point-to-multipoint radiowave propagation

This article presents results of a wide-band measurement campaign conducted at 38 GHz. The objective of the research was to determine multipath and time varying channel behavior of short-hop millimeter-wave point-to-multipoint radio links during various weather events. 73963 power delay profiles (PDPs) were captured on three links, each comparable to proposed local multipoint distribution systems (LMDS) in a campus environment. Multipath was observed in unobstructed LOS links during rain but not during clear weather. Short-term variation of the received signal over 1-2 min observation periods is described by a Rician distribution with a K factor which varies as a function of rain rate. Measured rain attenuation exceeds Crane's (1996) model predictions by several decibels. A novel prediction technique is presented that applies canonical antenna patterns and site specific information to estimate worst case multipath channel characteristics including relative power, time of arrival (TOA), and angle of arrival (AOA) of each multipath component. New metrics, the excess delay zone and relative power zone, are defined and contour plots are developed to determine potential reflectors from an area site map. These results and models provide useful guidelines for the design of millimeter-wave wireless communication systems.

V-band amplifier using InGaP/InGaAs/GaAs heterostructure MESFETs with asymmetric Au gate head

Self-aligned n/sup +/ i-InGaP/n-InGaAs/i-GaAs heterostructure MESFETs (N-MESFETs) with a gate length of 0.16 /spl mu/m were developed for applications to microwave and millimeter-wave wireless communication systems. A T-shaped Au/WSiN gate was used and the 0.8-/spl mu/m-wide Au gate head was deliberately shifted toward the source in order to reduce the parasitic feedback capacitance. Shifting the Au gate head by 0.2 /spl mu/m, the gate-to-drain capacitance decreased by 43 fF/mm and the maximum stable gain was improved by 1 dB. V-band monolithic microwave integrated circuit (MMIC) amplifiers fabricated with the asymmetric gate head field-effect transistors (FETs) achieved a gain of 9.7 dB at 55 GHz; their chip size is only 0.95/spl times/0.85 mm/sup 2/.

Low-loss micromachined filters for millimeter-wave communication systems

High-performance planar micromachined filters at 37 and 60 GHz are presented. The filters consist of a 3.5% bandwidth two-pole Chebyshev filter with transmission zeros at 37 GHz, 2.7% and 4.3% bandwidth four- and five-pole Chebyshev filters at 60 GHz, and an 8% bandwidth elliptic filter at 60 GHz. Silicon micromachining techniques combined with micropackaging have been applied to allow for very high-Q resonators resulting in low-loss filters. The 37-GHz two-pole filter exhibits a 2.3-dB port-to-port insertion loss. The 2.7% and 4.3% four- and five-pole Chebyshev filters at 60 GHz exhibit 2.8- and 3.4-dB insertion loss, and the 8% elliptic filter exhibits a 1.5-dB insertion loss. These values show a large reduction of insertion loss compared to conventional planar techniques, and can be used for planar low-cost millimeter-wave wireless communication systems.