When it comes to coupling, filters give the designer a window or opening to do something else within a certain frequency range. Both broadwall (uni-directional) and dual-directional (forward and reverse power) can be used in systems to sample power levels. The filter than relies on the impedance mismatching to direct the RF energy.
According to Microwaves101, “The coupled port on a microstrip or stripline directional coupler is closest to the input port because it is a backward wave coupler. On a waveguide broadwall directional coupler, the coupled port is closest to the output port because it is a forward wave coupler. Filters, which usually operate on two port networks come in a variety of options as well, including lowpass filters (LPF), high-pass filters (HPF) and band-pass filters (BPF), among others.
Watch the video above for a preview of Microtech’s waveguide coupler and filter products, presented by Jim McGregor at IMS 2014. Be sure to check out other videos from IMS 2014 over at Engineering TV.