A broadband low cost millimeterwave slotline detector on low permittivity substrate

A broadband low cost millimeterwave slotline detector circuit is proposed that can efficiently be realized on a low permittivity substrate (ε_r= 2.2) which is required for the integration of an antenna. The experimentally approved design achieved a voltage sensitivity of 1660 mV/mW at 77 GHz, with more than 1000 mV/mW between 62 and 85 GHz, a tangential signal sensitivity below -45 dBm and a 1-dB-compression point at -14.8 dBm. The sensitivity is about the same as for commercially available waveguide detectors despite the unfavourably low substrate permittivity. The compact design and the low cost allow the integration of a larger number of such slotline detectors with antennas on a single substrate for a receiver array in a millimeterwave focal plane imaging system.