C-Band Downconverter

This project is constructing a C-Band downconverter for use with terrestrial based transmissions, the frequency range is 4750 – 5850 MHz (IF is 1050-2150 MHz with LO at 3700 MHz).

The antenna is a 400mm 25dBi dual polarity dish that was originally designed for 4900 MHz public safety band. The dish has wide bandwidth and a 7° horizontal and vertical beamwidth.

Dual Polarity C-Band dish.

Rear-mounted equipment box for downconverter.

Currently, I am just using horizontal polarity as shown below.

Antenna to downcoverter RF coupling.

The downcoverter is constructed using the following mini-circuit components:

• ZX60-542LN-S+ 4400-5400 Low Noise Amplifier
• VHF-3500+ High Pass Filter
• ZX05-C60-S+ 1600-6000 Double-Balance Frequency Mixer
• VLF-1800+ Low Pass Filter
• ZX60-542LN-S+ Broadband Amplifier
• ZRL-3500+ 700-3500 MHz Amplifier
• ZKL-2+ 10-2000 MHz Amplifier
• ZFBT-6GW+ 0.1-6000 MHz bias-tee
• ZSN-3700AC+ Synthesizer (Local Oscillator)
• Miscellaneous attenuators to optimize RF and IF levels as appropriate

C-Band downconverter in equipment box.

Here is a first-signal test with some local WIFI access point.

Local WIFI Test.

Some unknown local digital signal (probably from some microwave link).

Unknown microwave link signal.

In case you are wondering what the prototype looked like.

The ugly prototype.