Yes — the Sherwood Observatory solar radio dish you mean operates at about 2.8 GHz (2800 MHz), not 12 GHz.
At 2.8 GHz, the wavelength is about 10.7 cm, which is a particularly important frequency in solar radio astronomy because it is used to measure the F10.7 solar radio flux.
The dish is essentially looking at radio emission from the Sun’s atmosphere, particularly the upper chromosphere and lower corona. The emission at this frequency comes mainly from thermal bremsstrahlung (free–free emission) and, around strongly magnetised active regions, gyroresonance emission.
With such a system they can observe:
- Overall solar radio brightness and how it changes from day to day.
- Active regions associated with sunspots, which can produce enhanced 2.8-GHz emission.
- Solar flares, which can cause rapid and sometimes very large increases in radio emission.
- The gradual rise and fall in solar activity over the approximately 11-year solar cycle.
- Solar drift scans, where the dish is held stationary and the Sun passes through its beam. This produces the familiar hump-shaped trace and can also be used to estimate the antenna beamwidth.
The internationally used F10.7 index is the integrated radio flux from the whole Sun at 2800 MHz. It is usually expressed in solar flux units (sfu), where:
1 sfu = 10^-22 W m^-2 Hz^-1
A quiet Sun might be around 65–75 sfu, while during high solar activity the F10.7 value can exceed 200 sfu.
This makes Sherwood’s experiment quite closely related to what you’ve recently been doing with your Discovery dishes at 1423 MHz. In both cases you’re detecting the Sun as a broadband continuum radio source. Your system is working at about 21 cm wavelength, whereas Sherwood is observing at 10.7 cm. The physical contributions to the solar emission differ somewhat at the two frequencies, but the basic experiment — detecting an increase in received power as the Sun crosses the antenna beam — is very similar.