A communication card or communication device is provided that includes an antenna for transmitting/receiving communication waves; a variable matching unit which can vary a circuit parameter; a directional coupling unit for extracting a reflected signal from the antenna; a detection unit for extracting the amplitude of the reflected signal; a control unit for outputting a control signal; an amplifier for amplifying a high frequency signal at a RF band; a frequency converter for converting an IF band signal into a RF band signal or a RF band signal into an IF band signal; a modulator/demodulator for modulating an IF signal to obtain a baseband signal at the transmission and demodulating an IF signal to obtain a baseband signal at the receiving; a baseband processor for processing the baseband signal; and a card interface for exchanging data with an information device.