Satoru Horiuchi

Wideband Planar Folded Dipole Antenna With Self-balanced Impedance Property

A planar folded dipole antenna that exhibits wideband characteristics is proposed. The antenna has simple planar construction without a ground plane and is easy to be assembled. Parameter values are adjusted in order to obtain wideband properties and compactness by using an electromagnetic simulator based on the method of moments. An experimental result centered at 1.7 GHz for 50 impedance matching shows that the antenna has bandwidth over 55% . The gains of the antenna are almost constant (2 dBi) in this frequency band and the radiation patterns are very similar to those of a normal dipole antenna. It is also shown that the antenna has a self-balanced impedance property in this frequency band.

Comparisons of simulated and measured electric field distributions in a cabin of a simplified scale car model

The electric fields inside and outside a car must be carefully determined when designing a wireless communication system to be employed in the car. This paper introduces an effective simulation method and a precise measurement method of electric field distributions in a cabin of a simplified scale car model. A 1/3 car model is employed for ease of measurement. The scaled frequency of 2859MHz, 3 times 953MHz, is employed. The use of a moment method simulator utilizing the multilevel fast multipole method allows calculations to be performed on a personal computer. In order to judge the accuracy of simulation results, convergence of simulation output in accordance with segment size (triangle edge length) changes is ensured. Simulation loads in the case of metallic body only and a metallic body with window glass are also shown. In the measurements, an optical electric field probe is employed so as to minimize the disturbances that would otherwise be caused by metallic feed cable; precise measurement results are obtained. Comparisons of measured and simulated results demonstrate very good agreement which confirms the accuracy of the calculated results. 3-dimensional electric field distributions in the car model are shown and 3-dimensional standing wave shapes are clarified. Moreover, calculated and measured radiation patterns of the car model are shown so the total electric field distributions around a car are clarified.

Design and fabrication of multiband p-i-n diode switches with ladder circuits

Single-pole double-throw switches composed of p-i-n diodes are proposed for multiband operations. A ladder resonance circuit is introduced to simplify their configuration and to reduce the cost. The isolation greater than 20 dB and the insertion loss less than 2 dB are achieved in experiments at three frequency bands: 1.6, 2.5, and 5.8 GHz. Resonance frequency variations are investigated in detail for two types of switches consisting of: 1) lumped circuit elements and 2) semimicrostrip elements. The variations on the semimicrostrip configuration are about 25% of those with lumped circuit elements. The proposed switch does not influence the switching speed and signal distortion characteristics. It also showed good temperature stability from -30/spl deg/C to +85/spl deg/C.

A study on wider bandwidth of bow-tie antenna with folded elements

It has been reported that the bow-tie can be miniaturized by adding folded elements [1]. The addition of folded element can shift the lowest operating frequency to the lower frequency. Consequently, the antenna area can be miniaturized to 31 % of conventional bow-tie antenna area. However, the addition of the two folded elements causes degradations of VSWR characteristics and the bandwidth for VSWR≤2 is narrower than conventional bow-tie antenna. In this paper, we investigate the shape of folded elements for suppressing the VSWR characteristics degradations and wider bandwidth.