Active Antenna System for One and Two Dimentional Phased Array Operation

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Phased array operation of active antennas is based on in-phase synchronized oscillation of element antennas. Both analytical and experimental investigation was carried out to obtain the dependence of mutual admittance and synchronization phase differene between two adjacent active antennas on antenna separation, and showed that the ranges of antenna separtaiton for in-phase synchronization are almost independent of the number of antenna elements.For Frequency controlled one- and two-dimensional phased array operation of bi-directionally coupled active antenna arrays, it was annalytically showen that phase differences between adjacent antennas can be varied up to 90 degrees by changing only the free-running frequencies of the edge antennas by the same amount in the opposite direction to each other.Since accurately controlled phased array operation needs uniformity in couplings between adjacent antennas, we proposed a new method to compensate for the nonuniformity in radiative couplings … More using resistor placed transmission-line couplings. It was confirmed in experiments under the compensation for up to four elements one-dimensional arrays and up to 3 * 3 elements two-dimensional arrays that active phase array behaviors almost agreed with the analysis can be obtained.For phased array operation of bi-directionally coupled one-diemnsional arrays which are controlled by injection signals with different phases at both the ends, beam steering angle of <plus-minus> 15 degrees was obtained in an experiment for a three active patch antenna array. It was analytically shown that there are undesired modes in this type of phased array systems. The undesired modes can be effectively suppressed by introducing a little deviation in the free-running oscillation frequency of either of the end active antennas. Suppression of undersired modes enlarges the steering angler. PSK modulation of antenna array outputs by PSK signal injection was also simulated, which clarified that the number of rise cycles of the output phases increases with the number of element antennas and is approxinately 150 cycles for a practical six-element arra Less