Matsushita Electric Industrial Co., Ltd.

Takayuki Matsumoto

Hiroaki Kosugi

Hisashi Adachi

Makoto Sakakura

Takashi Enoki

Yoshio Horiike

Yoshishige Yoshikawa

Yoshiyuki Yokoajiro

An antenna apparatus includes a minute loop antenna and at least one antenna element. The minute loop antenna is provided to be electromagnetically close to a dielectric substrate including a grounding conductor, has a predetermined number N of turns and a predetermined minute length, operates as a magnetic ideal dipole when a predetermined metal plate is located closely to the antenna apparatus, and operates as a current antenna when the metal plate is located apart from the antenna apparatus. The antenna element is connected to the minute loop antenna, and operates as a current antenna. In the antenna apparatus, one end of the antenna apparatus is connected to a feeding point, and another end of the antenna apparatus is connected to the grounding conductor of the dielectric substrate.

Antenna apparatus utilizing minute loop antenna and radio communication apparatus using the same antenna apparatus

In accordance with a loop open/close control signal, an analog switch closes or opens a loop including a voltage controlled oscillator, a variable frequency divider, a phase comparator, and a first loop filter, the analog switch, and a second loop filter. In order to reduce the change of frequency caused when the open loop state is set immediately after the output frequency is changed, the second loop filter uses a capacitor which shows properties of a small change of capacitance in response to an applied voltage and a small hysteresis. In another embodiment, the voltage controlled oscillator includes a second diode, one terminal of which is grounded, connected in reverses parallel to a first diode switch which switches the output oscillation frequency ranges of the voltage controlled oscillator.

Frequency synthesizer with controllable loop filter

A power amplifier amplifies a modulated carrier signal having an amplitude modulation component and a phase modulation component to generate a transmission signal. Part of the transmission signal is extracted by a monitor circuit. The detection signal detected by an envelope detector is compared with a burst control signal by a differential amplifier. The resulting error signal is input to a gain control terminal of a power amplifier through a sample and hold circuit, thus forming a feed-back loop. The sample and hold circuit outputs a sample signal during the transmission signal ramping-up and ramping-down periods, thus effectively turning ON the feed-back loop to an ON to control the transmission signal ramping-up and ramping-down. The sample and hold circuit outputs the hold signal during a modulated data transmission period, effectively turning OFF the feedback loop. As a result, a burst transmission output with a stable transmission power level can be obtained.

Burst signal transmitter

In a feedback loop, a modulation carrier signal is amplified or attenuated by a variable gain amplifier (2). A part of a transmission signal amplified by a power amplifier (3) is extracted by a monitor circuit (4) , and is detected by an envelope detector (6). This transmission envelope signal and a distortion-free standard envelope signal produced from a standard envelope generator (7) are compared in an error detector (8). An error signal obtained by amplifying the error of the two signals and a DC voltage are added in an adder (9). A gain control terminal (11) of the variable gain amplifier (2) is controlled by using this adder output signal as the control signal. The envelope detector (6) is capable of varying the attenuation quantity of the variable high frequency attenuator (61) and the load resistance value of the variable load circuit (63). Therefore, the dynamic range of the transmission monitor circuit monitor output corresponding to the output voltage of the envelope detector in a predetermined range can be expanded.

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Kadoma, Japan

Takayuki Matsumoto