Filmbrid Installation

Merrimac Filmbrid™ Couplers are low cost, four port, stripline networks. As Directional Couplers they appear under the C2F series, and as Quadrature Hybrids under the QHF-2-G and QHF-3-G series.

They are designed to work with both microstrip (ground plane on only one side of circuit) and balanced stripline (ground plane on both sides of circuit), but optimum performance can only be realized when the coupler is properly installed onto the circuit. Needless to say, the degree of care necessary increases with frequency.

Figure 1(a) Ideal Substrate Thickness

Figure 1(b) Excess Substrate Thickness

Balanced stripline installations are handled in much the same manner as microstrip except that clearance for the Filmbrid coupler is made in the upper ground cover plate. Installation then becomes identical to the microstrip case.

Tab terminals on Merrimac’s standard couplers are either 0.052 in. wide or .080 in. wide and are primarily designed to be fastened to printed circuits on soft substrate. For an additional charge tabs may be pre-tinned, however this does limit shelf life to six months. Circuits printed on hard substrates may require narrower terminals which Merrimac can provide on request.

Figure 1(c) Insufficient Substrate Thickness