A microstrip antenna with small size and light weight is useful for wireless camera. In this paper. the characteristics of stacked microstrip antenna which radiates a circularly polarized wave are investigated experimentally and the utility for wireless camera system is discussed.
A circular ring sicrostrip antenna with an elliptical slot on its center is nuaerically and experimentally analyzed for the circular polarization. In the numerical analysis, the antenna is modelled as a cavity with finite admittance wall on its inner and outer apertures. The electro magnetic fields vithin the dielectric substrate are expressed in terms of Bessel and trigonometric functions. By applying the method of least-square to the impedance boundary condition at apertures. the fields are determined. constructive parameters for clrcular polarization are evaluated.
By investigating several kinds of micro-patch antennas. We have developed so called a modified transmission line antenna (MTLA) or a transmission line sodified loop antenna (TLMLA). These antennas consist of mainly two parts, one is transmission line part which determines input impedance and the other is radiation part to determine directional pattern and gain. In this paper, providing two TLMLAs Which are designed for low band and high band of VHF-TV band respectively, we have developed a VHF-TV receiving antenna with relatively compact size useful for indoor antenna.
For AM/FM B.C. and Cellular mobile telephone (MT) in vehicles, two antennas are usually necessary. However, an AM/FM/MT triway antenna is desired and one with coils is used presently. This paper presents a design of the triway antenna with double sleeves.
In designing of medium wave antenna duplex system, it is considering the SWR variation in the AM transmission bands. When impedance was varied in the antenna systems which makes IPM (incidental phase modulation) distortion in the modulated AM signal. Cause of IPM disiortion makes from amplitude or phase differences between the upper and lower sidebands of AM signal. The medium wave Antenna duplex system design is using the SWR minimize method which is more useful for the AM stereophonic broadcasting.
Describes a new method for measuring the AM signal distortion (IPM : Incidental Phase Modulation) caused by AM to PM conversion at the output of an AM radio transmitter is thus presented together with a measuring instrument for analyzing the IPM distortion. The IPM is important to evaluate the quality of the AM radio transmitter used for stereophonic signal broadcasting since the IPM is occur at the outputs of solid-state and vacuum tube amplifiers in the AM transmitter.
Many FETs used at the radio transmitter of NHK Murasumi Radio Transmitting Station were damaged by lightning in 1989. The major causes of damaging FETs are transient voitage and current due to load change and induced surge voltage by lightning. Described are an analysis of transient voitage and current and some effective measures to protect madium-wave radio transmitter from lightning.
When the load condition of the transmitter changes by the antenna-induced lightning surges, large transfent voltage and current which may damage the power devices occur in the transmitter. In this paper, we analyze them by computer simulation, and show that the load impedance seen from the power amplifier with antenna base sborted should be approximately equal (inductive load), or twice (capacitive load) to the abselute value of the matched load impedance.