Radio communication apparatus and radio communication method

A radio communication apparatus that down-converts a transmitted radio signal to an intermediate frequency band on a receiving side, the radio communication apparatus comprising:

• a transmitter equipped with an intermediate frequency band modulator for modulating an input signal and outputting it as a modulated intermediate frequency band signal, a local oscillator for outputting an unmodulated carrier, a multiplier for multiplying the modulated intermediate frequency band signal and the unmodulated carrier and outputting a modulated radio frequency band signal, a combiner for combining the modulated radio frequency band signal from the multiplier and the unmodulated carrier output on a branch line from the local oscillator to produce a combined signal and outputting the combined signal, and a transmitting antenna for radio transmission of the combined signal;
• and
• a receiver equipped with a receiving antenna for receiving the combined signal from the transmitting antenna, a band-pass filter for extracting a component of the unmodulated carrier from the combined signal received by the receiving antenna, an injection-locked oscillator for regenerating the unmodulated carrier from an output of the band-pass filter, a multiplier for multiplying the modulated radio frequency band signal in the combined signal from the receiving antenna and the unmodulated carrier from the injection-locked oscillator to produce a modulated intermediate frequency band signal, and an intermediate frequency band demodulator for demodulating the modulated intermediate frequency band signal from the multiplier.

A radio communication apparatus that down-converts a transmitted radio signal to an intermediate frequency band on a receiving side, the radio communication apparatus comprising:

• a transmitting equipped with an intermediate frequency band modulator for modulating an input signal and outputting it as a modulated intermediate frequency band signal, a local oscillator for outputting an unmodulated carrier, a multiplier for multiplying the modulated intermediate frequency band signal and the unmodulated carrier and outputting a modulated radio frequency band signal, a first transmitting antenna for polarizing the modulated radio frequency band signal from the multiplier in one direction and transmitting the polarized modulated radio frequency band signal, and a second transmitting antenna for polarizing the unmodulated carrier output on a branch line from the local oscillator orthogonally to the one direction and transmitting the polarized unmodulated carrier;
• and
• a receiver equipped with a first receiving antenna for receiving the polarized modulated radio frequency band signal from the first transmitting antenna, a second receiving antenna for receiving the polarized unmodulated carrier from the second transmitting antenna, a multiplier for multiplying the polarized modulated radio frequency band signal from the first receiving antenna and the polarized unmodulated carrier from the second receiving antenna to produce a modulated intermediate frequency band signal, and an intermediate frequency band demodulator for demodulating the modulated intermediate frequency band signal from the multiplier.

A radio communication method that down-converts a transmitted radio signal to an intermediate frequency band on a receiving side, the radio communication method comprising the steps of:

• modulating an input signal in an intermediate frequency band to produce a modulated intermediate frequency band signal to a modulated radio frequency band signal;
• using a local oscillation signal on a transmitting side to up-convert the modulated intermediate frequency band signal to a modulated radio frequency band signal;
• transmitting the local oscillation signal and the modulated radio frequency band signal simultaneously from the transmitting side as a radio signal;
• and
• receiving the radio signal at the receiving side;
• down-converting the received signal by multiplying a component of the local oscillation signal that has been used for up-conversation on the transmitting side and transmitted to the receiving side and a component of the modulated radio frequency band signal contained in the received signal to generate a multiplication component and thereby produce a modulated intermediate frequency band signal;
• and
• demodulating the modulated intermediate frequency band signal.