Abstract: There is provided an antenna device including a substrate, an earth section which is disposed on a portion of the substrate, a feed point which is disposed on the substrate, a loading section disposed on the substrate and constructed with a line-shaped conductor pattern which is formed in a longitudinal direction of an elementary body made of a dielectric material, an inductor section which connects one end of the conductor pattern to the earth section, and a feed point which feeds a current to a connection point of the one end of the conductor pattern and the inductor section, wherein a longitudinal direction of the loading section is arranged to be parallel to an edge side of the earth section.

Abstract: A mobile communication terminal includes: a signal transmission section having a predetermined default value for a transmission characteristic; an antenna to be used at least by the signal transmission section; a separate circuit section sharing ground with the signal transmission section and the antenna, and being different from the signal transmission section; a monitoring section monitoring a change in a use state of the terminal related to the separate circuit section; and when the signal transmission section transmits a signal using the antenna, if the monitoring section detects a change in the use state of the terminal, a transmission-characteristic adjusting section adjusting a transmission characteristic of the signal transmission section from the default value to a characteristic optimized for the use state.

Abstract: There is provided an antenna device including a substrate, an earth section which is disposed on a portion of the substrate, a feed point which is disposed on the substrate, a loading section disposed on the substrate and constructed with a line-shaped conductor pattern which is formed in a longitudinal direction of an elementary body made of a dielectric material, an inductor section which connects one end of the conductor pattern to the earth section, and a feed point which feeds a current to a connection point of the one end of the conductor pattern and the inductor section, wherein a longitudinal direction of the loading section is arranged to be parallel to an edge side of the earth section.

Abstract: The surface acoustic wave device has the surface acoustic wave transducer, which consists of the positive electrode finger 102, the negative electrode finger 204, and the floating electrode 300, which are formed on the surface of the langasite single crystal substrate, where the substrate orientation and the surface acoustic wave propagation direction are chosen so that it may have the natural unidirectional property. When the wavelength of the surface acoustic wave is ?, each above-mentioned electrode is formed along the surface acoustic wave propagation direction, so that the width of above-mentioned positive electrode finger and the negative electrode finger may be about ?/8, the distance g between each center of the positive electrode finger and the floating electrode may be 13/40??g?14/40?, and the width W of the floating electrode may be 11/40??W?13/40?.