ArtisanRadio wrote: “The FCC has (almost) always based their decisions on reasons other than physical principles.”
The early technical decisions for AM/FM/TV broadcasting such as the transmitter power, frequency, transmitter site location, required antenna efficiency, and permitted radiation pattern were made by the FCC with due respect to the…[Read more]
Personal observations/opinions …
… about Broadcast Stations:
- The early commercial radio stations served and grew their listener base by broadcasting programs that most people wanted to listen to, even though listeners had to buy new, and relatively expensive receive systems to do that.
- Present-day commercial radio station owners are…
R.Powers & I have talked strictly and only about elevated ground-leads at a serviceable level to establish security and reachability by the operator, 9-feet at the most.
Everyone is able to promote and install whatever unlicensed transmit system they wish to.
Actually, the topic of elevated Part 15 AM antennas was first introduced in this thread by Rich Powers End80, with a post from which the clip below was taken…
“… Outdoor Part 15 transmitters which are elevated and well grounded is the standard and well established method of install. Ground mounts are something new. …”
RE: … a completely legal install could feasibly achieve over a mile radius providing the conditions (terrain, ground conductivity, ect.) are optimal.
Possibly. But other things equal, not with the coverage radius and reliability of an illegal installation such as the transmitter+3-meter whip installed on the top of a tall mast, and…[Read more]
An abundantly-confident Carl Blare wrote (in part): … Rich hasn’t shared any insight from his point of view as to why legal operators would be treated the same as pirates. … Therefore, for all of Rich’s claim of truth and accuracy his post earns the mark of incomplete.
The description of my “Part 15” setup included this: 3m Base-d…[Read more]
RE: I’ve never come across a single indication found in any published documentation … or for that matter in any technical calculations that 15.219 achieved greater distances than about a mile.
NEC4.2 shows that a 3m Base-driven Whip+Tx @ 10m AGL, 10m Lead from Tx to Ground Rod, 100 mW d-c input to Final RF Amplifier, 65 mW PA RF Output Powe…[Read more]
Example of “Obstruction Loss” to a MW AM Signal
Q: What loss of field intensity does a single private home cause to the groundwave propagation of a MW AM signal?
A: The signal strengths shown on a Tecsun PL-880 receiver tuned to a 500W AM broadcast station located 55 miles from the receiver location were …
Outside the east wall: 37 dB…[Read more]
Below is a graphic showing how that condition can be true.
Examine the region between 50 and 100 meters from the transmit antenna of a “Part 15” AM station (distance is plotted along the horizontal scale of the graph).
The total field intensity along the horizontal plane is shown by the topmost line plotted on the graph, and references the…[Read more]
My last post didn’t say or imply that all obstructions have loss, just described how any loss that might exist in an obstruction would affect a weak or strong e-m wave while it was passing through that obstruction.
Even though a signal may be weak within an obstruction such as a building, the field usually recovers to the same strength beyond the…[Read more]
RE: But the conclusion is the same: higher field strengths can penetrate obstructions which weaker field strengths cannot.
What do you think about this explanation?
- For a given set of propagation conditions, obstruction loss in percent of transmission and/or decibels of loss is the same for all e-m field intensities, regardless of the…
RE: “You’ve not made a response to any of the views expressed in this thread of yous Rich. You asked, we answered. Is your reaction only silence? Or are you still mulling it over?…”
Still mulling it over.
I expect that to take a very long time, as many of the responses made to my opening post continued the practices I was h…[Read more]
RE: … maybe it’s possible that some obstructions have little or no effect on MW signals? Comments?
Comment: Yes, that is a “given”except in the near field of re-radiating obstructions.
If the obstruction is a non-conductor then it has no near field of its own.
Imported from a recent post on Part15.org, comments to which are embedded below:
I’m personally getting rather tired of the discussions surrounding Part15.219 (or RSS210) antennas, ground leads, etc. The intent always appears to be negative in nature, and an attempt to discourage current and future Part 15 broadcasters. …
From co…[Read more]
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