《A Beam-Steering and -Switching Antenna Array Using a Coupled Phase-Locked Loop Array》.pdfVIP

638 IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 57, NO. 3, MARCH 2009 A Beam-Steering and -Switching Antenna Array Using a Coupled Phase-Locked Loop Array Sheng-Hong Yan, Student Member, IEEE, and Tah-Hsiung Chu, Member, IEEE Abstract—We present the analysis and experimental results of a The array of coupled oscillators synchronized by the injec- beam-steering and -switching antenna array using coupled oscil- tion locking mechanism is commonly named coupled oscillator lators and phase-locked loops. With the use of a type-II coupled array (COA). The output signals of a COA can have a uniform phase-locked loop array and an external reference signal, the an- tenna array can steer its beam by a single control voltage, reduce progressive phase distribution for beam steering by properly the beam-pointing error arising from the phase errors of the oscil- tuning the free-running frequencies of the oscillators [4]–[12]. lator array, and hold its output frequency stably at the reference The COA can also offer its signals with the desired phase rela- signal frequency in operation. Using a double-pole double-throw tionship for the sum or difference radiation pattern through cor- switch and a difference amplifier at the center element of the an- rectly manipulating the coupling phases [13] or tuning the os- tenna array, one can switch the array radiation pattern between cillators [14]. Nevertheless, circuit fabrication inconsistencies the sum pattern and the difference pattern. Moreover, the beam- scanning range is extended to 90 by properly using frequency cause fluctuations in the free-running frequencies and ampli- prescaler