Decoupling of Isosceles Triangular Array by Loaded Parasitic Element in Combination With Decoupling and Matching Network

In this paper, decoupling of a compact isosceles triangular array is performed by a hybrid method consisting of loaded parasitic element (LPE) in combination with decoupling and matching network (DMN). By introducing a reactively loaded parasitic element at a suitable position on the axis of symmetry of the isosceles triangle, not only are the mutual couplings between the element at the vertex and the two elements on the base eliminated but also the circuit parameters of the base elements are well prepared for a DMN of a simpler form. Thus, the impedance matching of the vertex element and the decoupling and matching of the base elements can be implemented independently. The DMN of base elements comprises two impedance-transforming sections (ITS) and a
$\pi $
-shaped neutralization section (NS). The ITSs inserted between the antennas and NS convert the self-conductance to the system admittance and the trans-conductance to zero. The trans-susceptance is then compensated through the main line of the NS independently, and self-susceptance is canceled out by adjusting the tapped stubs subsequently. With all the explicit formulas derived, the design is systematic and straightforward. The presented compact isosceles triangular array with element separations of
$0.1\lambda $
and
$0.2\lambda $
is fabricated and measured. The results show that sound isolation of 35 dB and return loss of 21 dB is obtained with ECCs less than 0.02, validating the effectiveness of the hybrid decoupling technique.