Analysis of the Influence of the Substrate on the Characteristics of Compact Power Dividers

This paper presents the calculations for directional couplers fabricated on substrates with different dielectric constant values (2.5, 4.4, and 7.2). The research focuses on miniaturizing a consistent design using substrates with varying dielectric permittivity. The miniaturization approach involves the use of planar structures in the form of a T-circuit, which includes inductive elements at the edges and a central capacitive element. This design is specifically engineered to achieve a 90-degree phase shift and minimize insertion loss within the coupler's operational frequency band. Through these calculations, we were able to compare the performance of three conventional couplers and three miniaturized versions. After analyzing the results, it was found that significant improvements in miniaturization could be achieved. The study highlights how substrate parameters, particularly dielectric permittivity, influence the coupler's size and performance, offering valuable insights into optimizing compact coupler designs.