A printed bandpass filter is mounted on a precision substrate to eliminate
the need for post-fabrication tuning. The filter input is capacitively
coupled to a series of quarter wavelength resonators and the filter
output. The quarter wavelength resonators are printed as spirals to
reduce filter size. The resonators define the bandpass characteristics of
the filter. The filter also weakly couples the input signal to the filter
output in a manner to cancel the signal image. Mechanical clips mitigate
thermal stress on solder connections when the precision substrate is
mounted on a second printed circuit board.