3cm (10GHz)

This is an amateur band I have not really tried. 

Back in the 1970s, I made a Gunn diode oscillator and got a few feet. 

Some take it very seriously and run big dishes and high power. Some have used the band for EME QSOs. Others have played with it with wideband FM using Gunnplexers and similar oscillators. 

These days the equivalent to these are HB100 Doppler radar modules available for just over a pound.  I have not seen wideband FM transceivers built around these, but I am sure they exist. Some have even used these with a dish for ATV and achieved some astounding ranges.

See https://sites.google.com/view/g3xbm4/home/vhfuhfmicrowaves/homebrew/10ghz.

10GHz (3cm)

Microwaves have largely passed me by. Apart from making a Gunn oscillator in the 1970s  (I think) in some waveguide and testing it over about 10m indoors, I have done nothing at 10GHz. I did borrow a 1296MHz RX converter and did some tests many years ago.

Some take microwaves very seriously and regularly achieve some remarkable distances, often by rain scatter. Others play at 10GHz with WBFM.

See https://sites.google.com/view/g3xbm4/home/vhfuhfmicrowaves/homebrew/10ghz .

Low cost, high performance 10GHz receiver

Recently Ian G3KKD has been telling me about some remarkable results on 10GHz using an Octagon satellite LNB that is available for around £12-15 via eBay. This has a crystal controlled PLL and has good frequency accuracy, stability and phase noise. I believe the LNB outputs a signal around 600MHz which is then down converted to a suitable IF.

Using this set-up Ian can copy the 10GHz beacon GB3CAM at around 30km with just the LNB handheld in his front or back garden which is badly screened by tall trees! Using a small Sky dish, the signal is S9+60dB from a point just along the road.

Of course, with a small surplus satellite dish, a low cost TV USB dongle used as an SSB/CW RX at the LNB output frequency, this would make an excellent SDR for 10GHz with VERY low noise figure. The LNB quotes the NF as 0.1dB, which is remarkable.

With a small 10GHz FM or CW TX into a separate dish, a complete low cost 10GHz station is possible, probably for less than £50. I am sorely tempted to try this.

I have just seen Andy G4JNT's note about this http://www.g4jnt.com/PLL_LNB_Tests.pdf .