Transmission line loss of strip line of receiving antenna for the satellite TV composed of flat antenna(TDLA) with Plane reflector is a cause of reduction of total gain. It is reported effective to load a dielectric material in front of antenna element, in order to improve the gain of the antenna. In this paper, gain characteristics of several type of dielectric load for a antenna is investigated experimentally.
In this paper, Wire-Grid Method is applied for analysis of wire antenna on conducting bodies of arbitrary shape. This calculation procedures is achieved by using a wire-grid model instead of conducting body with a finite size. As the results, the input impedance show good agreement with experimental data.
A microstrip antenna array consisting of basic element radiators covered with dielectric parasitic element is investigated. In this paper, the effect of the parasitic element on the gain and characteristics of the antenna is also investigated. It is found that the parasitic elements increase the overall gain of the antenna.
The input impedance characteristics of the oblate spheroidal antenna is numerically analyzed. This antenna is a circular patch microstrip antenna sandwiched by the oblate spheroidal conductor with the same size of cross-section. The electromagnetic fields within the antenna cavity are expressed by the cavity model and their expansion coefficients are determined by the electric and magnetic-field integral equations on the antenna surface. The expression of input impedance is formulated from Poynting's theorem.
It is important for radar to distinguish target. In this paper, we will deal with one of the analysis for impulse response from the target. We used halfwave-length dipole antenna and calculate for current on the conductor and input impedance using moment method. Fast Fourier Transform is used to Transform frequency-domain to time-domein using algorithm of Cooley-Tukey. We can get quasi impulse response of conductive wire.
This paper describes a mthod of estimating flutter-disturbance to television reception caused by a helicopter. The disturbance is caused by interference between a direct wave to a receiver and scattered waves by a helicopter. The scattered fieldstrength is calculated by using a model of a helicopter, which is a combination of rectangular reflectors. In order to save computing time, intervals of calculation on a flight course is automatically selected on the basis of the direct to scattered fieldstrength ratio.
In this paper, sound attenuation properties of a circular absorptive duct are studied generally by varing the value of a complex reflection coefficient at its surface. In this study, at first, eigenvalue equations are solved by using a complex reflection coefficient and frequency parameter. Next, the sound attenuations between two vertical sections of the duct are shown, after sound intensities arc calculated. On the other hand, the above-mentioned theoretical results are confirmed by the experiments. We measured the complex reflection coefficients, the sound intensities and sound attenuations of two different ducts. The experimental results approximatery coincided with the theoretical ones.
For system design and effective use of frequency bands for mobile communication, it is necessary to know field distribution along roads where mobile stations move. This paper describes a result of calculation of field strengths due to a direct wave and single- and double-reflected waves, and delay times of the reflected waves, when a receiver moves along a road in a configuration model of buildings.
Recently, there is a demand to detect the position of a vehicle for applying to car navigation system. We proposed a position detection system using broadcasting signals which are available in urban area. Determination of position is done by finding the direction of broadcasting signal. As the result, we find it is possible to determine the position of the care by finding MF radio broadcasting signal in Fukuoka area.
All NHK's stations throughout Japan are linked by a program network using microwave circuits owned by NTT, Nippon Telegraph and Telephone Corporation. The network enables exchanging programs among local stations as well. The control of the networke plays an important role in broadcasting services. On top of the NTT circuits, transmission of programs through communications satellites and optical fiber links has become popularized recently, and is sure to be a vital means of NHK's network. In Fukuoka station, 'Kaisen-no-Kanrininsan', a system that functions as 'effective management of the network' has been designed for the purpouse of simplifying the management of the network. The system hasfunctions of the network charge indicator as well as the schedule control of the network. The system, which bears economical effects, now occupies a leading part of the network control.
NTV has created the Japanese characters' on-screen graphics system, using the technical knowledge gained by the experience of the Japanese-English simultaneous on-screen graphic system which was produced/established at the 3rd IAAF World Championships in Atheletics in Tokyo in 1991. This system is operated by receiving the host computers' data at the venue where we transmit from, but actually super-imposing our simultaneously produced Japanese character graphics, all done without This results in the benefit of delay compared to the host broadcaster's English superimposement. viewer in Japan where they can see in Japanese(where it used to be in English or some other language)the athletes' and sport's information of an event that NTV is transmitting from abroad.
As part of HDTV test broadcasting in Japan the commercial broadcasters and NHK jointly aired a special program on the Imperial wedding of Crown prince Hironomia and Masako Owada. The commercial broadcasters installed a temporary switching center in Fuji Television and were responsible for designing and managing a HDTV contribution transmission system through degital satellite and fiber optic circuitry. This report explains the system's technical and optical specifications.