Microstrip directional couplers with ideal performance via single-element compensation

Using Phase Relations in Microstrip Directional Couplers to Achieve High Directivity

“…But for higher directivity values, a modification in values is necessary to take care of the parasitic effects such as transmission line bends, junction discontinuities, via hole inductors, unintended couplings and the parasitics of the lumped elements. An optimization is performed using the microwave circuit simulator and an electromagnetic simulator 5 for the final values.…”

“…Dielectric overlays [3], [4] achieves a velocity equalization as the overlay brings the quasi-TEM mode propagation closer to a pure TEM mode. Lumped element compensation is explored in several works [5]- [7]. Moderate bandwidth and directivity levels were achieved using these methods.…”

High Directivity Microstrip Coupler Using Variable Width Structure

“…The wiggly line coupler [1] improves the directivity and suffers due to lack of design equation. The capacitive compensation was used to improve the directivity [2]; however the capacitor has to be placed in the narrow spacing between the coupled lines. The inductive compensation improves the isolation and needs the iteration design process [3,4].…”

A directivity enhancement for directional couplers using additional coupled lines

“…In a coupled-line directional coupler formed on thin multi-layered substrates, there are manufacturing constraints, such as the relatively narrow space between signal conductors and ground conductors. This constraint often prevents the matching of a coupled-line characteristic impedance Z C [1,2,3,4,5] with a load impedance Z L . This impedance mismatch causes undesired forward coupling in the directional coupler, thus degrading the directivity [6].…”