Described is a new MF radio transmitter using hybrid-modulation system Use of this system result in an AM transmitter with outstanding high over all efficiency (85% or more), audio performance and reliability.
This paper describes an example of the distortion caused by the output circuit, as an impedance transformer, in the MF transmitter for AM stereophonic broadcasting. The frequency response, both amplitude and phase, in the output circuit including the antenna cause to several distortions on the carrier wave modulated by composite AM stereophonic signal. The practical examples of characteristics of the output circuit and antenna are used for this calculations such as frequency response, separation, harmonic distortion and so on.
Lately, the demand of multi-media communications is growing in local area radio networks. However multi media communications needs techniques such as high speed transmission, variable bit rate transmission and the multiple access. In this paper, we propose a new system using a multicarrier modulation technique. Then we show that the proposed system can provide variable bit rate transmission with high frequency utilization efficiency.
By taking into consideration the high gain characteristics of a four-stacked circular-loop antenna and by distributing this antenna in a log-periodic arrengiment, an antenna with a wide bandwidth is proposed and used as receiving antenna of the outdoor antenna gain mesuring system in UHF TV band. The suppression effect, of reflected waves and the error between available and directional gains are experimentally discussed.