Method of calculating exciting coefficients for circular array antenna and radio unit utilizing the same

A receiver comprising:

• a circular antenna comprising a plurality of antenna elements disposed circularly;
• a coefficient calculator for calculating excitation coefficients for the circular array antenna based on a beam direction and a beamwidth of a desired antenna pattern;
• a receive frequency converter for converting radio frequency signals received by the circular array antenna to either intermediate frequency signals or baseband signals;
• and
• a plurality of receive beam formers, each of the receive beam formers for respectively multiplying either the intermediate frequency signals or the baseband signals by the coefficients calculated by the coefficient calculator and combining resultant signals,
• wherein the receive beam formers are coupled in parallel to the receive frequency converter,
• wherein the coefficient calculator is commonly coupled to the receive beam formers, and
• wherein the coefficient calculator comprises means for setting the number of beams which is equal to the number of receive beam formers.

A receiver comprising:

• a circular array antenna comprising a plurality of antenna elements disposed circularly;
• a coefficient calculator for calculating excitation coefficients for the circular array antenna based on a beam direction and a beamwidth of a desired antenna pattern;
• a plurality of receive frequency converters, each of the receive frequency converters for converting radio frequency signals received by the circular array antenna to either intermediate frequency signals or baseband signals;
• and
• a plurality of receive beam formers, each of the receive beam formers for respectively multiplying either the intermediate frequency signals or the baseband signals by the coefficients calculated by the coefficient calculator and combining resultant signals,
• wherein the receive frequency converter and the receive beam former are coupled in parallel to the circular array antenna,
• wherein the coefficient calculator is coupled to the receive beam formers, and
• wherein the coefficient calculator comprises means for setting the number of beams which is equal to the number of receive beam formers.

A transmitter comprising:

• a circular array antenna comprising a plurality of antenna elements disposed circularly;
• a coefficient calculator for calculating excitation coefficients for the circular array antenna based on a beam direction and a beamwidth of a desired antenna pattern;
• a plurality of transmit beam formers, each of the transmit beam formers for splitting a transmit signal into signals, the number of which is the same as the number of antenna elements of the circular array antenna, and respectively multiplying the signals by the coefficients thereby to form transmit beams;
• and
• a transmit frequency converter for converting the transmit beams of each of the transmit beam formers to either intermediate frequency signals or baseband signals,
• wherein the transmit beam formers are coupled in parallel to the transmit frequency converter,
• wherein the coefficient calculator is commonly coupled to the transmit beam formers, and
• wherein the coefficient calculator comprises means for setting the number of beams
• which is equal to the number of transmit beam formers.

A transmitter comprising:

• a circular array antenna comprising a plurality of antenna elements disposed circularly;
• a coefficient calculator for calculating excitation coefficients for the circular array antenna based on a beam direction and a beamwidth of a desired antenna pattern;
• a plurality of transmit beam formers, each of the transmit beam formers for splitting a transmit signal into signals, the number of which is the same as the number of antenna elements of the circular array antenna, and respectively multiplying the signals by the coefficients thereby to form transmit beams;
• and
• a plurality of transmit frequency converters, each of the transmit frequency converters for converting the transmit beams of the corresponding transmit beam former to either intermediate frequency signals or baseband signals,
• wherein the combinations of the transmit frequency converter and the transmit beam former are coupled in parallel to the circular array antenna,
• wherein the coefficient calculator is commonly coupled to the transmit beam formers, and
• wherein the coefficient calculator comprises means for setting the number of beams which is equal to the number of transmit beam formers.

A radio unit for use with

• a circular antenna having a plurality of antenna elements disposed circularly, said radio unit comprising:
• a calculator for establishing an antenna pattern of said circular antenna based on at least one of an arbitrary beam direction and an arbitrary beam width of a desired antenna pattern;
• a receive frequency converter for converting radio frequency signals received by the circular antenna to either intermediate frequency signals or baseband signals;
• a receive beam former for respectively multiplying either the intermediate frequency signals or the baseband signals by coefficients calculated by the coefficient calculator and combining resultant signals;
• a transmit beam former for splitting a transmit signal into signals, the number of which is the same as the number of antenna elements of the circular array antenna, and respectively multiplying the signals by the coefficients thereby to form transmit beams;
• and
• a transmit frequency converter for converting the transmit beams of the transmit beam former to either intermediate frequency signals or baseband signals,
• wherein the calculator is commonly coupled to the receive beam former and the transmit beam former.