Beam forming antenna
A beam forming antenna in which directivity directions of beams can be controlled at higher resolution of control is provided. The beam forming antenna includes a matrix circuit having multiple final output terminals and multiple antenna elements connected to the multiple final output terminals respectively. The matrix circuit includes a first sub-matrix, a second sub-matric, and adders which combine outputs of the first sub-matrix and outputs of the second sub-matrix. By selecting any input terminal out of the multiple input terminals of the first sub-matrix or the multiple input terminals of the second sub-matrix and inputting a signal, a signal having a predetermined phase difference between output terminals is output at the multiple final output terminals and the phase difference between output terminals has a differing value according to a selected input terminal.
1. A beam forming antenna comprising:
a matrix circuit having multiple final output terminals; and
multiple antenna elements connected to the multiple final output terminals respectively,
the matrix circuit including:
a first sub-matrix which is a Butler matrix having multiple input terminals and multiple output terminals;
a second sub-matrix which is a Butler matrix having multiple input terminals and multiple output terminals; and
adders which combine outputs of the first sub-matrix and outputs of the second sub-matrix,
wherein, by selecting any input terminal out of the multiple input terminals of the first sub-matrix or the multiple input terminals of the second sub-matrix and inputting a signal, a signal having a predetermined phase difference between output terminals is output at the multiple final output terminals and the phase difference between output terminals has a differing value according to a selected input terminal,
wherein when a signal has been input to any one of the multiple input terminals of the first sub-matrix, a signal is output from the multiple output terminals of the first sub-matrix;
wherein when a signal has been input to any one of the multiple input terminals of the second sub-matrix, a signal is output from the multiple output terminals of the second sub-matrix; and
wherein a phase difference between output terminals produced when any one of the multiple input terminals of the first sub-matrix and the multiple input terminals of the second sub-matrix will be one of all different values according to a selected input terminal.
2. The beam forming antenna according to claim 1 ,
wherein the first sub-matrix and the second sub-matrix include 3 dB hybrid combiners and fixed phase shifters.
3. The beam forming antenna according to claim 1 , further comprising:
a transmitting circuit; and
a switch to connect an output of the transmitting circuit to any input terminal of the multiple input terminals of the first sub-matrix and the multiple input terminals of the second sub-matrix.