Directional Coupler Compensation With Optimally Positioned Capacitances

Planar Directional Couplers and Filters

“…To overcome the tendency of forward wave coupling present in waveguides with inhomogeneous cross sections, wiggly-line technique originated from [45] is used. Many broadband and also high directivity couplers in inhomogeneous media have been reported [26,29,[46][47][48][49][50][51][52][53][54][55][56][57][58][59], but there is little information about maximum operating frequencies beyond 20 GHz and their special design requirements [27,28,30,60]. A comprehensive comparison of reported and commercially available backward wave couplers with the proposed coupler is given in Table 3.2.…”

“…[26]), but operation in the millimeter-wave frequency range could only be demonstrated with monolithic integrated circuit technology [27] and a quite high minimum operating frequency. The same holds true for meandered coupler configurations [28].…”

Using Phase Relations in Microstrip Directional Couplers to Achieve High Directivity

“…It is possible to reach a similar conclusion using the network theory (See Appendix). Hence we can write in this frequency range (24) (8) and the prescribed coupling level. For the 10 dB coupler, the theoretical phase deviation of from is less than 4.2 in .…”

“…Moderate bandwidth and directivity levels were achieved using these methods. A recent work [8] demonstrated a wideband compensation using interdigital capacitors. In another recent work [9] both high directivity and tight coupling were achieved by cascading couplers in a narrow bandwidth.…”

An ultra wideband, high directivity 3 dB coupler

“…In such couplers, good directivity and return loss are contingent upon equality between even and odd mode velocities. To this end, capacitors between the coupled lines were used in [1], [2]. In [2], the capacitors were realized in interdigital configuration.…”