I decided to modularize the TX and RX components of the 47 GHz transverter. That way I can test different configurations. The design will comprise of the TX and RX each feeding a dish mounted on a frame. This eliminates the need for a waveguide switch. The dishes will be mounted side by side on a frame - this will be covered in a separate post.
This particular project is for a receive downconverter.
The key component of the downconverter is a Scientific Atlanta receive mixer assembly I purchased at Microwave Update. The assembly consists of a waveguide isolator on the mixer input. The mixer is a harmonic type mixer and has an LO input in the 12 GHz range. The IF output is ~1GHz. A CTI brick oscillator feeds an amplifier which amplifies the LO to the mixer. The output of the mixer feeds a ~1GHz post amp. As you can see the LO is attenuated. The brick oscillator is actually made for the 11GHz band but I adjusted the cavity to 12GHz. I have a surplus 100mhz phase locked oscillator (another surplus
item from MUD). This oscillator requires a 10 MHz input. The mixer is a Ku type mixer made for 35 GHz but feeding with 12 GHz, I did pick off a signal around 912MHz indicating an LO of 48GHz high side when detecting a test signal at 47088 MHz. I have not confirmed the conversion characteristics of the mixer working in this configuration (I dont have the equipment to do that) so that will have to be done at a conference where test equipment is available. I originally had this built on a bread board but am now packaging in an enclosure. The input will be via WR28 waveguide with a square flange. I still need to integrate the 100 MHz PLL and 10 MHz oscillator and also a second low noise post IF amp in the 900-1000MHz range.
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