Importance

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Abstract

It is an object of the present invention to provide a portable terminal which reduces an antenna standing-wave ratio and absorbs reflected waves without inserting an isolator so that a stable operation can be obtained efficiently with a compact, low-price body. To achieve the above object, there is provided a portable terminal having antenna sharing means for sharing an antenna between transmission and reception, a power amplifier for high-power transmission and a low noise amplifier for reception, which comprises: suppression means for suppressing an antenna standing-wave ratio within a given range; a circulator for use as the antenna sharing means; and a protective circuit connected to an input end of the low noise amplifier for reception, wherein when a signal is transmitted from the power amplifier, a reflected wave output from the power amplifier and reflected by the antenna is suppressed by the suppression means to a given value or less, and losses of reflected wave are increased by extending a path of the reflected wave from the antenna to the power amplifier through the circulator carrying the reflected wave to the protective circuit and returning it from the protective circuit to the power amplifier, whereby the amount of the reflected wave to be sent back to the power amplifier is reduced. Therefore, such an isolator as used in the conventional does not need to be provided at the output end of the power amplifier for protecting the power amplifier, and as a result, the portable terminal can realize high efficiency with a low distortion characteristic.

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First Claim