Modified Photoimageable Thick-Film Process for Millimeter-Wave Rectangular Waveguide Applications

This paper presents the design and fabrication of a class of dielectric filled rectangular waveguides using a multilayer photoimageable thick-film technique. The original fabrication technique is modified to shorten fabrication time and improve waveguide thickness to reduce transmission structure losses. The materials used are first characterized before the wave-guiding properties are extracted. The fabricated waveguides show excellent results in term of loss and a 1% variation in permittivity over a wide frequency range of 10-100 GHz. To demonstrate the practical applications of this modified fabrication technique, 5th and 3rd order band-pass filters are designed and fabricated. The different incertitude on the fabrication issues is studied showing an effect on the bandwidth and central frequency. The measurement results of the fabricated prototypes agree well with the simulated ones. A broadband 3 dB coupler is designed and fabricated covering both V and W bands. The measurements results for this circuit show good performance with 23% of bandwidth and are in good agreement with the simulations.