Decoupling of an isosceles triangular three element array with one reactively loaded dummy element

An effective decoupling scheme to reduce the mutual couplings between radiating elements in an isosceles triangular three-element antenna array is proposed in this paper. It is shown from the network point of view that one dummy element with reactive load is sufficient to decouple a compact array with two different mutual couplings. Having had decoupled, each radiating element can be independently matched. The working principle is mathematically proved. A prototype three-monopole compact array working in 2.5 to 2.6 GHz is designed, fabricated and measured. Measured results show that 10 dB return loss and 20 dB isolation bandwidth is around 160 MHz at 2.6 GHz. The radiation efficiency is improved from 70% to nearly 90 % and envelope correlation coefficient is also reduced significantly within the band of interest.