Synthesis of symmetric lumped element quadrature hybrids

Abstract

The synthesis of a class of lumped element quadrature hybrids is described. The circuits are applicable to RF systems, and have wide operating band potential. The circuits possess symmetry in both horizontal and vertical planes. Two examples have been designed and constructed; one, a second-order example, operates over a 50–150 MHz band, exhibiting 0.3 dB loss, 23 dB return loss and isolation and 0.2° phase accuracy, the other, a third-order example operates over a 2–30 MHz band exhibiting 0.3 dB loss, 25 dB return loss, 30 dB isolation and 2° phase accuracy.