S7 = 13uV across 50 ohms.
S7 =22dBuV across 60 ohms
S7 = 3.2 pW across 50 ohms
S7 = -85 dBm across 50 ohms
Nice post Dave.
S7 = 13uV across 50 ohms.
S7 =22dBuV across 50 ohms
S7 = 3.2 pW across 50 ohms
S7 = -85 dBm across 50 ohms
Nice post Dave.
John that was just an arbitrary "S" unit I picked. I am to lazy to do the math, just philisophicaly discussing these concepts. 13 uv sounds like quite a bit so well within the service area of a licensed TX. I guess S3 or something like that would be closer? I've kinda wondered why no one in this group hasn't calibrated a receiver/antenna for field strength. My Cushman sprectrum analyzer claims it can read field strength if you have the "antenna factor number" or something like that. I rememer seeing it in the book but had no idea how to build a calibrated antenna for testing on the BC band. I bet the FCC would be forgiving if you came within 3 DB or so and that should be an easy target for under 200 bucks. I bet the noi guy was probably up 10db or more with that antenna. By the way isn't his standard different than a homebuilt because type accepted equipment falls under the part that specifies field strength? Am I wrong, I'm just going by memory?
I have an neat old 1947 RCA BTA-250L bc tx and I bet even though type accepted I would probably exceed part 15 even into a dummy load but boy the 828's and 810's look cool at night!! 🙂
And one last thing John did you mean EMP class when you gave the "ground the world round" quote. I attended a government 2 week class 30 years ago to harden up 911 centers and I remember that quote too. Dave
You can use a calibrated loop antenna for signals below 30 MHZ. the of course you would have to add in the antenna correction factors for the loop and cable attenuation based on length to the observed measurement.
With regard to EMP, nope, EMC Electro Magnetic Compatability. (getting things to work together) However, coming from a Military Contractors world, I understand EMP. For many years I managed an Open Area Test Site (OATS) for FCC compliance as well. (ISM, Part 15 Devices, etc..) Also was involved in Part 68 testing, but to a lesser degree.