Naobumi Michishita

FDTD analysis for printed dipole antenna with balun

This paper presents the analysis of the printed dipole antenna on dielectric substrate by FDTD method, and investigates the feed circuit structure.

A polarization diversity antenna by printed dipole and patch with a hole

Uplink diversity reception is mandatory for base station antennas in order to decrease multipath fading and to compensate for power unbalance between uplink and downlink. Mobile telephone services began with vehicular mounted mobile terminals which radiate vertical components. Recently, everyone uses a handset placed near the ear at a tilt angle. This operating condition results in an increase in the horizontal radiation component in the uplink, and polarization diversity is effective for diversity systems. The polarization diversity antenna using vertical and horizontal components has the merit of minimizing the antenna installation space, and has been adopted for Japanese cellular systems. This paper proposes a novel and compact diversity antenna element consisting of a printed dipole for vertical polarization and a patch with a hole for the horizontal component (see Kuga, N. and Arai, H., IEICE Technical Report, vol.AP2000-78, 2000). We analyze this polarization diversity antenna by the FDTD method to optimize its antenna parameters.

Mutual coupling characteristics of binomial and Chebyshev arrays using 16 element patch antennas with choke for repeater systems

Repeater systems will become practical in the IMT-2000 system in order to provide service in locations where presently radio waves cannot reach. We have examined an antenna structure, in the form of a patch array antenna of 4 elements, for a repeater (Michishita, N. et al., IEE 12th Int. Conf. Antennas and Propagation, 2003). At the edge of the ground plane is a choke structure, and this structures parameters effect the FB (front-to-back) ratio. We investigate a 16 element patch array antenna which references the 4 element design method and present the mutual coupling characteristics of the 16 element patch array antennas with chokes. The repression of the FB ratio by a choke is small in the case of the 16 element array, because its side lobe level is large. We examine the effect of restraining the mutual coupling using a binomial and Chebyshev array by controlling the amplitude of each element. The binomial and Chebyshev arrays effect the restraint of the side lobe level, and the mutual coupling can be made less than -100 dB by choosing suitable parameters.