Patent ID: 7439918

Claim:
An adaptive antenna apparatus comprising: N number of antenna elements for receiving radio signals, said antenna elements including at least a first antenna element and a second antenna element, wherein said first antenna element has an electrical length L 1 larger than λ/2, where λ is a wavelength of a radio signal, wherein said second antenna element has an electrical length L 2 which is different from the electrical length L 1 and equal to or smaller than λ/2, and wherein said adaptive antenna apparatus further comprises: a plurality of A/D converters; N number of antenna switches, each of said antenna switches being operable to (i) receive a radio signal from a respective antenna element, (ii) connect the respective antenna element to any one of said A/D converters and ground, and (iii) transmit the received radio signal to any one of said A/D converters and ground; a plurality of output switches, each of said output switches being (i) connected to a respective A/D converter, (ii) operable to receive a radio signal from any of said antenna elements via the respective A/D converter, and (iii) operable to output the radio signal received via the respective A/D converter to a first output when said output switch is in a first position and to a second output when said output switch is in a second position; an adaptive controller for (i) receiving, from said second outputs of said output switches, each radio signal received by said first and second antenna elements, and (ii) adaptively controlling said adaptive antenna apparatus to form a radiation pattern including a number of nulls substantively in a direction of an interference wave by adjusting at least one of an amplitude and a phase of each radio signal received from said first and second antenna elements, wherein the number of nulls is less than, equal to or greater than N−1 and the degree of freedom of said antenna apparatus is greater than N−1; a controller for controlling whether each of said output switches is in the first position or the second position; and a demodulator for (i) receiving each radio signal adjusted by said adaptive controller and (ii) receiving, from said first outputs of said output switches, each radio signal received by said first and second antenna elements as unadjusted radio signals.