There are a number of laboratory grade RF Noise generators on the market. They are all extremely expensive ranging in the thousands of dollars. This is beyond the reach of most individuals. In contrast, there are some low cost RF noise generator schematics floating around the Internet which are all based upon Zener diodes. The high end generators are generating “SHOT” noise as opposed to the lower end devices which are generating thermal or Johnson noise. [2]
The problem with Zener diodes is the noise bandwidth. All the circuits I have seen have cutoff frequencies in the Megahertz range. The one noise circuit I saw used in the Gigahertz range, that had a Zener diode, was actually amplifier noise, which is Johnson noise, and had spectrum distribution problems due to the several stages of amplification. A common carbon resistor could been substituted for the Zener diode with no affect on the output.
The alternative to Zener diodes is the avalanche diode specifically designed as a RF noise generator which generate SHOT noise. These devices are difficult to acquire and have very high prices which often exceed the entire cost of all the parts and components needed to build the instrument.
Shot noise, a type of noise which can be modeled by a Poisson statistical process, is temperature and frequency independent, in contrast to Johnson–Nyquist noise, which is proportional to temperature with the spectral density decreasing with increasing frequency. White noise and Poisson noise sources may be specified in certain types of advanced measurements of network cables, radar, satellite systems, GPS and advanced communications systems where spectral noise power density is critical. This also applies to jitter, A/D quantum errors and other error statistics in measurement and detection systems. All military grade jammers use SHOT noise generators. The field of noise generation and measurement is a highly advance specialty.
Professor Jackson at Jackson Research has discovered a semiconductor that generates RF noise like an avalanche noise diode into the Gigahertz range, but at Zener diode prices. He has raw laboratory data and now needs to build up a professional grade instrument. To achieve this goal, he has launched a new KickStarter fund raiser to build up a number of units. [1]
[1] https://www.kickstarter.com/projects/jrmagnetics/rf-broadband-noise-generator-2
[2] D.A Bell, M.A., Ph.D., M.I.E.E., “Electrical Noise”, D. Van Nostrand Company, Ltd. 1960.
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