A Novel Miniaturized Branch-Line Coupler With Equivalent Transmission Lines

Abstract

Abstract-In this paper, a novel miniaturized branch-line coupler (BLC) operating at 1.675 GHz is proposed. Partially meandered lines and dual transmission lines equivalent technology are used as the coupler's shunt arms, producing significant reduction by more than 68% compared with the conventional coupler. Moreover, the coupler can equally divide the input signal with 90 • phase of difference while maintaining the initial power from the source with a simple structure. The simulated and measured results are in good agreement, thereby verifying the design concept.

A miniaturized harmonic suppressed 3 dB branch line coupler using H-shaped microstrip line

“…. Several design techniques to reduce the physical size of the BLC and to suppress undesired spurious response have been reported . Coupler of symmetrical structure with four microstrip lines and four chip inductors is used in Ref.…”

“…, a T‐shaped topology with shunt open‐stub with high low has been used for size miniaturization of BLC. To decrease the size of the coupler different transmission line models like square‐split resonator , reduced transmission line using recursive loaded stubs , and dual‐transmission line have been reported. In Ref.…”

Compact microstrip branch-line coupler with wideband quadrature phase balance

“…Photonic band gap structures and other slow wave structures were used to reduce the size based on slow‐wave effect, with a maximum size reduction of 72%. Artificial transmission lines (ATLs) , dual‐transmission lines , discontinuous transmission lines and incorporation of stubs in transmission lines are few methods reported in literature for bringing in compactness. Meandering of transmission lines has been proven to be a very effective method for size reduction especially at lower frequencies .…”

Realization of Miniaturized Quadrature Hybrid Coupler With Reduced Length Branch Arms Using Recursively Loaded Stubs

“…With a T-model approach in one set of branch arms and implanting high low impedance based open stubs in the other pair of arms a miniaturized branch line hybrid is achieved in [9]. Branch arms are replaced by equivalent dual transmission lines where one of the lines is meandered resulting in a reduction of 68% in circuit size as reported in [10]. A technique of miniaturization of BLC by loading branch arms by complementary split ring resonators resulting in 66.14% size reduction is demonstrated in [11].…”

“…Therefore, numerous methods have been proposed to miniaturize these conventional designs of BLCs [3][4][5][6][7][8][9][10]. Fractal space filling shapes like Sierpinski curve has been used to design miniaturized branch line hybrid, rat race couplers and coupled line hybrids as reported in [3].…”