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This paper reports the design of a compact branch line coupler based on defected ground structure (DGS) in microstrip medium. Unit cell's (of DGS) equivalent circuit has been used to evaluate the performance of coupler. Based on this approach, a compact coupler has been realized at 2.4 GHz yielding a size reduction of 33% over the conventional coupler. [ABSTRACT FROM AUTHOR]

This paper reports a new design of microstrip directional coupler with high directivity. This directional coupler uses corrugated coupled lines and floating conductor in the ground plane of microstrip to enhance coupling. Based on this structure, directional coupler having 4.4% bandwidth has been designed at 4500 MHz with 10 dB coupling and 35 dB directivity. The designed directional coupler has been fabricated and tested for the validity of the design. Measured results are presented in this paper. [ABSTRACT FROM PUBLISHER]

Closed-form expressions for the propagation characteristics of coupled microstrip lines with a symmetrical aperture in the ground plane are derived. Expressions for the regular microstrip coupled lines have been modified using physical insights to incorporate the effect of the aperture. The accuracy of these expressions has been verified by full-wave simulations and compared with conformal mapping analysis. These expressions are accurate within 5% for a substrate whose thickness varies from 0.2 to 1.6 mm and permittivity in the range of 2–10. Designing a broadband filter based on planar multi-conductor coupled lines with aperture in the ground plane is demonstrated in this paper using the proposed expressions for its practical use. [ABSTRACT FROM AUTHOR]