High frequency, medium power gyrotrons (Gyrotron FU series) have been developed at the Fukui University as radiation sources convering a broad frequency band from millimeter to submillimeter wave region. We have performed cw operation of the Gyrotron FU IV. However, the output power was not stable (approximately several tens %) due to the fluctuation of the cathode potential (40 V). The output power was stabilized within several percent by controlling the anode potential. Such a technique was also used for amplitude modulation of the gyrotron output. Improved stabilization of output power and effective modulation will be achieved by stabilizing the cathode potential
There is a need for large deployable antennas with diameters larger than 10 m for space‐VLBI satellites and mobile communication satellites. Several deployment mechanisms have been proposed, each of which uses determined lines and points on a smooth prototype reflector surface. The basic structure is to use the reflector surfaces which are located between them as meshes or films.
This paper examines types of mechanical errors of a deployable antenna and its relation with the radiation characteristics. Its effects on the radiation characteristics are shown numerically. As a result, it is shown that the gain reduction is less than 0.18 dB by subdividing the reflector surfaces by equilateral triangles whose side is about one‐eighth the radius for a 2‐GHz band tension‐truss type antenna of 15 m diameter. With a penalty of an additional 0.1 dB, the number of approximating triangles can be reduced by about 30 percent by subdividing the outer portion of the reflector twice as roughly as the interior portion. However, it is important to add phase offsets.
It is shown that grating lobes appear in the sidelobe characteristics due to the periodic errors. The relationship between mechanical error and the effective error of the reflector surface is also clarified.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.