Abstract: An antenna structure with reduced bulkiness and capable of changing antenna directivity is provided. In order to achieve such an effect, the antenna structure includes a feed element of one of an inverted F type and a loop type, and a passive element of one of the inverted F type and loop type, and having a variable reactor so as to be capable of changing an electrical length, and the feed element and passive element are disposed with a predetermined distance therebetween.

Abstract: A reflector includes a pair or plural pairs of array antennas. Each array antenna is formed of an arrangement of a plurality of antenna elements formed on a surface of a waveguide. The array antennas are placed parallel to each other. Both ends of each array antenna pair are connected through a pair of waveguides. Information adding devices are inserted in the waveguides.

Abstract: A reflector includes a pair or plural pairs of array antennas. Each array antenna is formed of an arrangement of a plurality of antenna elements formed on a surface of a waveguide. The array antennas are placed parallel to each other. Both ends of each array antenna pair are connected through a pair of waveguides. Information adding devices are inserted in the waveguides.

Abstract: An antenna structure with reduced bulkiness and capable of changing antenna directivity is provided. In order to achieve such an effect, the antenna structure includes a feed element of one of an inverted F type and a loop type, and a passive element of one of the inverted F type and loop type, and having a variable reactor so as to be capable of changing an electrical length, and the feed element and passive element are disposed with a predetermined distance therebetween.

Abstract: An adaptive controller for an ESPAR antenna randomly perturbs a bias voltage vector V(n) composed of elements of bias voltage values Vm by a random vector R(n) generated by a random number generator, compares an objective function value J(n) of a cross correlation coefficient for a bias voltage vector V(n) before the perturbation with an objective function value J(n+1) of a cross correlation coefficient for a bias voltage vector V(n+1) after the perturbation, and selects and sets the bias voltage Vm corresponding to that when the cross correlation coefficient increases before and after the perturbation. Then the adaptive controller repeats the random perturbation and setting from the bias voltage of respective varactor diodes. This leads to that it is not necessary to provide a long training sequence signal, and the control process can be executed with learning so that a performance can be improved every iteration for search.

Abstract: An adaptive controller for an ESPAR antenna randomly perturbs a bias voltage vector V(n) composed of elements of bias voltage values Vm by a random vector R(n) generated by a random number generator, compares an objective function value J(n) of a cross correlation coefficient for a bias voltage vector V(n) before the perturbation with an objective function value J(n+1) of a cross correlation coefficient for a bias voltage vector V(n+1) after the perturbation, and selects and sets the bias voltage Vm corresponding to that when the cross correlation coefficient increases before and after the perturbation. Then the adaptive controller repeats the random perturbation and setting from the bias voltage of respective varactor diodes. This leads to that it is not necessary to provide a long training sequence signal, and the control process can be executed with learning so that a performance can be improved every iteration for search.