A taper filtering finline at millimeter wavelengths for broadband harmonic multiplication

The design of a taper filtering finline aimed at simultaneously mode matching and frequency selecting multifrequency signal is presented. Based on the superimposition of a smoothly corrugated taper and a sinusoidal-shaped filter, a low insertion loss (L<0.1 dB) at W band [75:110] GHz and a high rejected stop band in the third harmonic range (R band [225:330] GHz) are demonstrated. Both sections are numerically optimized using chain matrix techniques and assessed by means of full three-dimensional electromagnetic simulations.