Abstract: A frequency converter that includes a first low-pass filter and a band-pass filter with a first end operatively connected to a first end of the first low-pass filter. The frequency converter also includes a second low-pass filter with a first end also operatively connected to the first end of the first low-pass filter. The frequency converter, moreover, includes a first waveguide with a first end operatively connected to a second end of the second low-pass filter, with the first waveguide containing at least one frequency-mixing element, and with the first waveguide continuing for a specific length after the one frequency-mixing element and having a second end that is operatively short circuited. The frequency converter, furthermore, includes a second waveguide operatively connected to the one frequency-mixing element. The frequency converter is arranged such that the specific length of the first waveguide extends past the operative connection between the second waveguide and the one frequency-mixing element.