rich, your comment about the indoor to outdoor behavior of RF signals summarizes in a very compact way the results typically encountered, and I will utilize your statement in the section of the record relative to that aspect.
Appreciate it.
Hi Carl,
It is a joy to read what you have to say.
You have just given me the best thing I have read online in years and with your permission I think I will re-use it myself....."Any website that tolerates me must be great."
Cheers!
Jon Paul
"As with all computer programs, accuracy of the results depends on the accuracy of the input data (the model)."
Ahh...yet when the data input is assumed and not from actual tests or measurements, then the result is also assumed.
Don't you think it would produce better results by entering actual measured data..say from a system you set up, and then run that through the simulations to see the results?
Or have you already and just not telling anyone because those results are completely different from everything you have presented to date.
I'm not saying your data is flawed or useless, I am saying that it is all one sided...nothing but simulated input data resulting in simulated output data. In 99 percent of your charts and graphs dating back to 2007, all assume a perfect Earth ground and all assume a monopole sitting on the dirt. The charts and graphs for elevated systems is also assumed, as there once again perfect grounds are entered as input.
Interesting this insatiable interest in grounds, and simulation data with perfect Earth ground.
The history suggests that perhaps if you had set up a Part 15 system and presented data thru NEC using information from that setup, people would be more receptive of the information.
You've managed to create division in what was once a rounded world of fellow engineers and radio enthusiasts. I would not doubt you have even managed to divert newcomers to the radio world from even getting started in it, to which I recall another discussion elsewhere to that very fact.
People begin to see how crooked the picture hangs on the wall and will ask who what where and why. There are a lot of people asking questions, and not just here either.
Good day! (no I'm not Paul Harvey) 🙂
RFB
Don't you think it would produce better results by entering actual measured data..say from a system you set up, and then run that through the simulations to see the results?
Better than that, I have modeled a real-world system that was set up by a broadcast consultant, who measured its radiated fields with an accurately calibrated Potomac Instruments FIM-41 Field Intensity Meter.
The results are linked here, and show very good correlation between the measured and the NEC fields.
Notice that perfect earth conductivity is not used in this NEC model. It is 6 mS/m, which is the conductivity value shown for this groundwave path in the consultant's chart at the bottom of that page.
I hadn't posted this link on Part15us earlier because it applies to a broadcast station, and also may be somewhat difficult to understand. But it does illustrate the accuracy of NEC vs. measured data.
The owner of one the largest U.S. manufacturers of FM broadcast antennas, who is also a registered professional engineer, once told me that he could calculate antenna performance with more accuracy than he could measure it 🙂
Well I understand the concept of scaled down analysis and often that's just fine. And although radio is radio, there is a huge difference between working with watts/kilowatts/megawatts/gigawatts versus milliwatts and nanowatts.
Ever try to feed a 6 bay turnstile antenna system with 11 nanowatts through a 3 inch heliax 240 feet up a tower?
Doesn't quite work too well.
Ever try feeding a 120 foot monopole over 120 ground radials with 100mW by just attaching to the existing ATU in the dog house?
Doesn't quite work to well.
In both cases, it took something besides large scale solutions to make the ant push the tin can.
Why don't you build yourself a Part 15 setup? I think that if you did, it would be the most efficient, the most performing Part 15 system to exist, one that would be envy of the entire low power radio world.
Imagine the following to something like that.
RFB
And although radio is radio, there is a huge difference between working with watts/kilowatts/megawatts/gigawatts versus milliwatts and nanowatts.
Only in terms of the hardware required for those systems.
But the underlying physics applying to the radiation of transmit systems of ALL power levels is uniform for a given frequency and antenna system configuration, and directly scalable with respect to radiated power.
I think it would be a good idea for you to construct a Part 15 system based on your analysis and charts and get some measurements and present those as well.
Just make sure it's functionally compliant. 😉
RFB
agreed.
Definition of FUNCTIONALLY COMPLIANT:
It just barely works but is legal.
Responding to comments of others...
I began to use the term functional compliance because of the many posts I had read describing Part 15 AM systems installed at the top of a tower, flagpole, TV mast, on a roof mount, etc using a long conducting path to an earth ground. Such systems were presented by their users as being compliant with §15.219(b) as long as the total length of the whip antenna and a short wire to a "massive" conducting path to an earth ground was 3 meters or less.
But as has been shown by physics and the practical experience of users of such systems, the total radiating length of those conductors can be much greater than 3 meters, making such systems not functionally compliant with §15.219(b).
Some have reported that FCC inspectors have not cited such configurations, and that may be true, for whatever reason. But that wouldn't make those installations functionally compliant with §15.219(b), just not cited for their non-compliance.
From its description and pics, Neil's new outdoor system is functionally compliant, and he reports good reception on his truck radio for at least a one mile radius. So his system is quite a bit better than barely working.
You know exactly why these days it is best for AM setups to be sitting on the dirt, when prior there was NEVER any concern about setups on poles or roofs or towers. Regardless of your position or opinion, it was a fact and never an issue for decades with elevated systems.
The other side of that coin is the generous offerings of technical data on systems sitting on the dirt, or elevated systems with grounding schemes that "fit" into this functionally compliant basket.
So on one side there should be a great many thanks to you for providing that data. In all aspects, your not obligated to do that or anything else. I think that is quite admirable.
As the old saying goes, there are two sides to every story, two sides to every coin.
The other side is that you created a situation that never existed, nor was of any concern to the FCC, thus you manipulated the circumstances with the skill of a Romulan. You created the scenario for which forced the FCC's hand by constant nagging and complaining to the point where it began to fit along with the big boy's agenda. That alone is the reason for why the situations are as they are today.
I find that to be as crooked as what these so called politicians are doing at this very moment...creating the problems, causing the reactions, then handing out the solutions.
This is the reason for all the confusion and wonder what your agenda is. It's the same confusion people have with their so called saviors who turned their backs on them, and they can't figure out why.
Gotta give you some credit Rich. However, as many have suggested, perhaps the reactions to your solutions would not be so problematic if you joined the party and built a system, using your own specs from your charts and graphs, take some measurements and compare the data between real world and simulation.
So what if the results are different. They will be I promise you. Who cares. The point is that you managed to grab attention spanning numbers of websites and forums. However the one thing you left out was a setup in the real world to show as an example.
So why not provide that one little thing that will most likely put a little more respect towards your endeavors. Set up a system. What will it hurt? What prevents you from doing that? It certainly cannot be technical. It certainly cannot be lack of enthusiasm, and it certainly cannot be due to possibly not being functionally compliant.
As one person had already alluded to you, real world results are far more enlightening than a static piece of paper.
I can tell you this, as long as your stuck inside that NEC program, no one is really going to pay that much attention until you present something that is of the real world. You might get a few who will follow, but no where near the total that has been witness to all this.
Eventually at some point, those that are following the paper trail will veer off and get back into the real world. You should too.
RFB
My present and future antenna designs do not include long vertical ground paths located above the ground because it seems clear to me that it would radiate and would not be compliant with part 15 rules for AM band.
I have said that without use of the word "functionally".
I put up the TH with ATU simply because they claim FCC Part 15 Acceptance while using the ATU.
I refer to it as a "warm fuzzy feeling of security".
On the ISS InfoSpot (built around the TH & ATU) web page they specifically advertize using up to 300 feet of coax and mounting the ATU way up there and they profess it to be accepted.
I'm counting on that as my defense.
RFB wrote: I can tell you this, as long as your stuck inside that NEC program, no one is really going to pay that much attention until you present something that is of the real world.
That already has been done, but maybe you missed it. The link I posted earlier in this thread shows the very close correlation between the real world, accurately measured field intensity data of an installed system, and that of a NEC model of that same system.
Here is the link once more, and I hope that people actually will view it. I noticed very few views of that graphic from the previous posting here (the report of such views does not identify anything about the viewer, not even the IP address).
i think the issue is were talking about flea powered stations into a base loaded shortened vertical not a full power am running into a 90 deg tower over a full quarter wave ground system.
you need to build a functionally compliant ground mounted tx running 100mW input to a 3m meter base loaded radiator over some sort of large buried radial system and compare NEC data to the real world reading of that installation.
someone of your knowledge and background should have no trouble performing such a task.
i'm sure you have access to a backyard to plant such a system at ground level.