A study on active integrated antenna and beam steering using coupling phases of oscillator antenna

Abstract

Electronic beam steering is a key technology for several commercial and defense applications, including radar, air surveillance, collision detection, and smart antennas for wireless communications. Typically, phased arrays rely on devices known as phase shifters to ensure properties of an antenna array for the reception or transmission of electromagnetic radiation. This approach is conceptually simple, but can be complicated in practice, especially in recent efforts to develop monolithic T/R modules where it is difficult to integrate the phase shifter circuitry, RF distribution network, control signals and DC bias lines along with the planar antenna. However, there exist several beam steering alternatives which do not rely on the use of phase shifters, such as frequency scanning and multiple beam forming networks. An attractive feature of injection locking techniques is the ability to manipulate the phase distribution without phase-shifting circuitry, suggesting a potential strong for low cost beam scanning systems. In this dissertation, we propose a new technique for electronic beam scanning without a phase shifter circuitry. A constant phase progression which is independent of both the number of oscillators and the locking range is accomplished by controlling the coupling phase of the outermost coupling circuits only, while that of the innermost coupling circuits is zero and all free-running frequencies of the oscillators are same. A constant phase progression is a piecewise linear function of coupling phases only and is not arcsine nonlinear function of free-running frequency. This technique is tested using an experiment of a six-element oscillator array. The radiation pattern could be continuously steered over a range from -18.5$\deg$ to 17$\deg$ off broadside. This scan range is very close to the theoretically achievable scan range. The active integrated antenna that can be used for subelement of active array antenna was investigated antenna elements f...