We present testing of a 180GHz prototype filter bank spectrometer and report on designs for larger channeled millimeter-wave filter banks at 50-183 GHz. This technology will be utilized in the development of a novel low-SWaP-C microwave sounding sensor. It works by amplifying the broadband signal with an LNA then channelizing with the millimeter-wave filter bank. Each channel of the filter bank is detected by a separate diode. The sensor system enabled by the millimeter-wave filter bank has a great potential for measuring 3D atmospheric water vapor and temperature by detecting the 183 GHz water line. We will report here our progress in utilizing the sensor for on the ground detections of humidity and preliminary designs for the use of the sensor on a small satellite. Satellite based microwave radiometers are the most important driver of global weather forecasting. Current sensors rely on high-Swap-C LO/mixer/RF components. We will demonstrate that the maturation and adoptions of our novel sensor system would greatly improve weather forecasting. The prototype millimeter-wave filter banks were fabricated using a micro milling CNC with a tolerance of 5-microns and is a waveguide coupled to five spectrometer channels. The spectrometer channels are resonant with a tuned center frequency. We tested a single channel prototype to determine sensitivity. Testing was performed by driving a VNA extender with a signal generator to input a sweeping signal into the prototype.