Keren Li

Gain Enhancement of H-Plane Sectoral Post-Wall Horn Antenna by Connecting Tapered Slots for Millimeter-Wave Communication

We propose a millimeter-wave antenna to serve as an element antenna for a multi-sector switched-beam antenna, which can be fed by a post-wall waveguide. Several tapered slot antennas are connected to an aperture of an H-plane sectoral post-wall horn antenna whose radiation pattern is narrowed in the H-plane to further narrow the pattern in the E-plane. Moreover, the aperture of each tapered slot antenna is loaded with a dielectric to increase the gain. We designed an antenna whose gain is over 16 dBi in the frequency band of 57-66 GHz. The wideband property is experimentally examined.

Wideband planar antennas for millimeter-wave wireless communications

In this paper, we have presented a planar antenna with stacked microstrip patch configuration and a two-driving-patch feeding network for the millimeter-wave wireless applications. The developed antenna exhibits good antenna performance: a wide bandwidth larger than 14 GHz, relatively high gain larger than 9 dBi and stable radiation patterns over the whole band of mmWPAN. The main radiation part of the developed antenna has a small size about 4.5 mm (L) x 2.5 mm (W) x 0.5 mm (H). This antenna can be considered as a suitable antenna for the portable devices used in the millimeter-wave wireless communication systems such as mmWPAN or WirelessHD.

Implementation considerations of patch antenna array for 60GHz beam steering system applications

Beam steering antenna is expected in 60GHz wireless communication system to improve the signal to noise ratio and obtain high gain with wide cover range for high speed WPAN application. In this paper, patch antenna arrays with planar topology are investigated by synthesizing the network losses and devices such as phase shifters. The investigation results can provide a valuable guide line for the further implementations to the highly integrated beamforming systems. Moreover, the array antenna system perfor-mances, i.e. maximum gain, directivity, radiation patterns, element phase sensitivity, are analyzed under different element number and based on electromagnetic simulation and computational methods. It is found that the half wavelength square patch arrays can obtain maximum ± 45° angle scanning range in E-plane and ± 40° range in Hplane with peak gain variation of 3dB. It can be shown that to achieve 6dBi gain with ± 45° beam steering range, a 13-element array with inter-element spacing of λ0 and full 360° phase shifter are required if only passive components are employed.

Improving gain of H-plane sectoral post-wall horn antenna for millimeter-wave communication by connecting tapered slots

We propose a millimeter-wave antenna that can be assembled using several printed boards. A post-wall horn antenna structure and tapered slots are responsible for the narrowing of the radiation pattern in the H-plane and the E-plane, respectively. Further, to improve the matching with free space and obtain a better radiation pattern, a dielectric projection that tapers is attached to the antenna tip. Numerical results show that a working gain of ≥17 dBi can be obtained in the frequency range 57- 66 GHz.

Wideband stacked microstrip patch antenna on thin PTFE substrate for millimeter-wave personal area network (mmWPAN)

Since FCC released the unlicensed use of 60GHz frequency band, more and more intensive researches and industry interests, including the IEEE standardization of millimeter-wave personal area network (mmWPAN) [1], have been done for the applications of high speed, short distance wireless communication. An antenna with high gain (more than 10dBi) or beam steering feature is the most expected in such a system to provide enough system link budgets [2]. In [3], a simple stacked microstip antenna with two driving patches, fabricated on the Teflon substrate with the thickness of 0.254mm, was reported to have 9 dBi gain covering all frequency bands (57–66GHz), allocated in Japan, US and EU. However, our recent work [4] shows that the basic circuit components, such as bends, folded lines, suffer from quite high losses on the 0.254mm-thick substrate. This will cause serious problems in the future circuit integration. To reduce the losses of feeding networks caused by thick substrate, a thinner substrate with 0.127mm thickness is employed in this paper. However, antenna on the thinner substrate has narrower bandwidth and lower gain. Stacked patch antennas with different configurations based on the work [3] will be presented first to show the frequency bandwidth characteristics and radiation performances on the 0.127mm-thick substrate. Aiming at obtaining wideband and higher gain, a series-parallel mixed stacked patch antenna array is also proposed as in Fig. 1.

Antenna space diversity and polarization mismatch in wideband 60GHz-Millimeter-wave wireless system

This paper presents a study on the fading behavior in wideband 60GHz-Millimeter-wave (MMW) wireless system. The evaluation is carried out based on a two-ray propagation model, with considering the large propagation loss of the multi-reflected waves other than the first reflected wave at 60GHz-millimeter-wave. The study focuses on the strong fading effect due to the large variation of antenna location compared to the short wavelength (about 5mm) and the wide frequency range (about 9GHz) in such MMW wireless system. The influence of the polarization mismatch of antenna is also investigated. To reduce the fading, we employ the technique of space diversity by introducing two or more antennas in receiving side. We perform an optimization of the locations (heights) for these antennas. From the simulation results, we obtain some optimal heights with which the fading effect can be reduced in less than 3dB. The simulation results also reveal how the polarization mismatch, in two different cases of antenna rotations, influences the system performance, and how space diversity reduce the fading as well. The antenna used in simulation is a planar patch antenna which is considered suitable for portable wireless handset. The radiation pattern is obtained from electromagnetic simulation. This paper demonstrates that by employing multiple antennas with optimized antenna locations can significantly reduce the fading for the 60GHz-MMW wireless system.

Proposal and design of Yagi-Uda antenna for UHF-ITS mobile terminal

A Yagi-Uda antenna with a small short interelement distance (d) of approximately 0.025λ is proposed for use as a UHF-band ITS in-vehicle antenna. A distributed constant line is added to the center of the reflector dipole as a reactor. It is shown that a Gw of more than 4.7 dBi can be achieved in the 10-MHz bandwidth. The antenna can be placed near the body of a car without any significant deterioration in the gain. Moreover, Gw can be made to exceed 6.7 dBi by suitably adjusting the distance of the antenna from the body of the car.

60 GHz wideband antena with air filled stacked patch structure

A wideband antenna is designed and implemented by using air filled stacked structure on thin PTFE substrate for millimeter wave personal network area (WPNA) application. The optimized antenna achieves more than 22% impedance bandwidth and more than 9 dBi gain over the frequency band 57 – 66 GHz.

Research and development on UHF band inter-vehicle communication systems

In Japan, the current analogue terrestrial TV broadcasting service is scheduled for retirement on July 24, 2011. It was considered that the 10 MHz band on the UHF band from 715 to 725 MHz band would be used for the use of ITS. This paper summarizes the latest research and development results on IV communication systems on UHF band regarding use case, PHY and MAC layers and a prototype.

Measurement of transmission line characteristics using linear resonator technique in millimeter-wave/Terahertz-wave regions

This paper presents a measurement technique and measured results of transmission line characteristics in millimeter-wave and Terahertz frequency regions. Linear resonator technique was employed in the measurement. Formulas for transmission performance of the resonator with gaps coupling to the measurement system, and a simple formula for compensation of the resonant frequency shift from the true resonance due to the coupling have been presented. Microstrip lines fabricated on a 50um-thick liquid crystal polymer (LCP) substrate were used in our experiment. Measured results of transmission line characteristics such as effective dielectric constant, attenuation constant and Q-factor from 220 GHz to 330 GHz, have been provided.