1.9 GHz Compact Low Loss Dielectric Duplexer Designed by Dual Mode Waveguide Transmission Line Method
A new small sized and low loss 1.9 GHz band dielectric duplexer has been developed. 1.9 GHz TM110 dual mode monoblock dielectric resonators, which designed to have much smaller volume (27 cc) and high unloaded Q(5000), have been constructed by using new precise molding techniques. And to insure that we are able to simulate and design optimized electrical performance of the duplexer accurately, we have proposed a dielectric dual mode waveguide transmission line design, method. The duplexer thus designed and manufactured has excellent performanc. The volume is 200 cc, insertion loss is 0.45 dB, and attenuation is 85 dB.
Miniatrzed Dielectric Duplexer Using TM Triple Mode Resonators For 800MFHz Band Cellular Base Station
This paper describes a new technology of very compact 800MHz band dielectric duplexer. We has developed a dielectric TM triple mode resonator, that consists of monoblock high K ceramics. By using this, a much size-reduced dielectric duplexer has been designed and manufactured at 800MHz band. The duplexer which has each 6 poles has elliptic function characteristics and low insertion loss of about 0.8dB, high attenuation of 90dB. The volume is about 222cc, that is 1/5 of conventional cavity duplexer. This duplexer is very useful for cellular base station.
In search of optimum chest radiography techniques.
A nation-wide study of chest radiography in Sweden had previously revealed a large variation in the physical and technical factors involved, in particular the radiation dose. In this study the image quality could not be assessed unambiguously. The aim of the present study was to try to establish a correlation between visual grading of radiographs and physical and technical factors in order to find the optimum chest X-ray system. The physical and technical performance of 24 chest units was evaluated. Radiographs were taken of an anthropomorphic chest phantom supplied with test structures simulating various pathologies. Image quality was assessed by visual grading analysis of the radiographs. The physical and technical parameters of the units rated best were used to exemplify good radiographic practice. The results were in agreement with the recommendations issued by the Commission of the European Communities (CEC). It was also shown that low radiation dose is compatible with high-quality radiographic imaging of the chest.