Yokowo Co., Ltd.

Yusuke Suzuki

Hirotoshi Mizuno

Tadashi Oshiyama

A multi-band antenna is adapted to operate in a first frequency band and a second frequency band which is lower than the first frequency band. In the multi-band antenna, an antenna element has an electrical length of &#xbe; wavelength of the first frequency band. The antenna element has a first end adapted to be electrically connected to a power feeding point, and a second end. An inductor is electrically connected between the second end of the antenna element and a ground in a serial manner. The inductor has such an inductance that an electrical length of the antenna element and the inductor corresponds to &#xbd; wavelength of the second frequency band.

Multi-band antenna with inductor and/or capacitor

The present invention provides an antenna for multiple bands employing a single antenna element, capable of operating in multiple frequency bands, and ideal for size reduction purposes. One end A of an antenna elementis electrically connected to a feeding pointand intermediate points B and C and the other end thereof is electrically connected via switches SWb, SWc, and SWd to a ground conductor. The electrical lengths of the antenna elementfrom the terminal to the intermediate points B and C plus connection lines from these points via the switches SWb and SWc to the ground conductor 14 and the electrical length from the one end A to the other end D plus a connection line from the other end via the switch SWd to the ground conductorare set to be capable of resonating different desired frequency bands. By closing one of the switches SWb, SWc, and SWd, one of the desired frequencies can be selected and the antenna can resonate with that frequency. Thus, the antenna employing the single antenna elementcan operate in multiple frequency bands.

Antenna for a plurality of bands

The present invention provides a broad-band antenna for mobile communication in which a desired antenna characteristic is obtained in plural frequency bands of a portable phone or the like. A metal platehaving a suitable shape is disposed on an upper surface of a carrierprovided on a circuit boardand a first and a second antenna elements functioning as inverted-F antennas respectively resonant at a first frequency band and a second frequency band higher than the former are formed by electrically connecting the metal plateto a grounding plateand the circuit boardby an earthing terminaland a feed terminalrespectively. A third antenna elementhaving a base end electrically connected to the feed terminaland resonant at a third frequency band higher than the second frequency band is provided on a side surface of the carrierends of the second antenna element and the third antenna elementare disposed to be spaced from each other by a distance of 0.1 wavelength or more of the third frequency band, and the end of the third antenna elementis disposed to be spaced from the grounding plateby a distance of 0.01 wavelength or more of the third frequency band. Besides, the third antenna element may be made resonant at a fourth frequency band higher than the third frequency band, and a matching circuit to perform matching for the third frequency band may be provided.

Growing community of inventors

Tomioka, Japan

Yusuke Suzuki