Waveguide dual-hole directional coupler is the simplest waveguide directional coupler, the main and the secondary waveguide through its public narrow wall two
Coupler A small hole is separated from the d= (2n+1) ΛG0/4, the λg0 is the waveguide wavelength corresponding to the central frequency, and n is a positive integer, and the general n=0 is taken. Coupling holes are generally circular or other shapes. When working in the center frequency, ΒD=Π/2, at this time d→∞; When deviating from the central frequency, the secβd has a certain number, at which point D is no longer infinite.
In fact, even in the central frequency of the dual-hole coupler, its orientation is not infinite, but only around 30dB. In short, the waveguide dual-hole directional coupler is based on the interference of the wave to achieve the direction of the main waveguide output, on the coupling of the same phase superimposed on the isolation of the reverse phase offset. In order to increase the coupling degree of the directional coupler and widen the working frequency band, the porous directional coupler can be used.