Effect of Number of Elements of a Reactively Loaded Ring Antenna Array on the Performance of Beamwidth Variation

We herein investigate the effect of the number of elements of a previously studied reactively loaded ring antenna array with respect to electronically variable beamwidth performance. The antenna has a unique ability to increase the effective antenna length by adding parasitic ring elements, which contributes to higher performance with respect to beamwidth variation. Monte Carlo (MC) simulations clarify that variable range of beamwidth can be improved effectively by increasing the number of ring elements M to 5. It is herein demonstrated for the case of M = 5 that the beamwidth toward the broadside direction can be controlled from 40deg to 145deg in the E plane, while maintaining the voltage standing-wave ratio (VSWR) to less than 3.0, where the antenna size is 0.32lambda times 1.32lambda. In addition, it is also confirmed that the number of estimated directions-of-arrival (DOAs) based on the reactance-domain multiple signal classification (MUSIC) algorithm can be also increased by increasing the number of ring elements.