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Has anyone designed or know of an existing ‘directional’ antenna array, adaptable to the Hamilton transmitter? I am positioned in a place where my designated service area is in a certain and specific direction, as opposed to a dense forest behind me. Unless I have a measurable audience among the wildlife, it would be beneficial to concentrate my signal toward an actual population of people… in a floodlight-like pattern, if possible. Of course, any such antenna must fall within the legal-length measurement. I guess a ‘beam’ antenna, like those used by HAMS, might be an area to explore.
Total posts : 45366I think you’ll find beams way too big at the frequencies we’re talking about.
A dipole is somewhat directional, but you’ll only get 1.5 meters on each side, and I’m not sure that would tune (or be even remotely efficient if you could tune it).
I suspect that a ground-mounted 3 meter vertical antenna with a great ground (including radials) would still outperform any directional antenna you might come up with.
Total posts : 45366Just kinda shooting from the hip here as we’re heading out the door pretty soon… but…
This beam idea might not be to crazy for this type of situation.
After all, the verticals we use now are technically much to short, yet the transitters are tuned to work into them. Who is to say that a beam that is also much to small wouldn’t work equally well?
Further, and again — just quick thinking — a beam antenna only has one actual driven element. basically a dipole. The other elements — the one behind it a reflector, and the directors in front that “focus” or concentrate the signal in a given direction, are parasitic e.g. not connected to the feedline, and wouldn’t count as part of the antenna.
I would think someone who could do some antenna computing could figure out a beam based on the shrunken vertical size we’re allowed, and come up with element size and spacing for a beam.
I would expect that as long as the driven elements are of legal length (let assume 1.5 meters per side of the boom) the antenna would be legal as the reflector and directors are not connected to the feedline — they are parasitic elements.
I do think there may be some useful experimentation to be done.
TIB
Total posts : 45366I suspect that by putting all your radials on the side toward the desired target the radiated signal from a vertical antenna will put all its strength in the direction the rials are pointing.
Total posts : 45366i was thinking same thing carl just posted. but we arent supposed to have ground radials.
Total posts : 45366Won’t help because your using line of sight, not skywave just pure ground wave, just simple point to point antenna height to antenna height and free space and a receiver turned your direction and one that is free of AC hum and noise will hear you. Get that antenna up in the air and let mother nature’s line of the geographic site do the rest, keep it away from things that will absorb your signal and waste burning up what little rf the fcc bestows on us, lucky fellows as we are in the 100 milliwatt class
Total posts : 45366
Total posts : 45366
Total posts : 45366here is wbt am radios antenna system notice they are tall and fat and hey are far away from anything that would absorb or reflect their energy but a lot of us use tripods or mount our antennas on houses and what’s happening is the little wattage we have is being wasted heating a roof or a tree or worse the ground…
Total posts : 45366Published on May 12, 2015Hamilton Rangemaster AM1000 for sale near Indianapolis on 1610. I can ship (at buyer’s expense) the transmitter, brackets, cable, power supply and antenna base (2-3 feet) but not the upper part of the antenna (a CB whip) but would highly prefer that the buyer come here and hear it in action and witness the great coverage first hand to avoid misunderstanding. Mounting it on the ground, even with a good ground, will not perform as well as being on the roof at 20′ with no ground. FCC approved as long as you use it exactly as it is. The audio of this video was recorded from an AM receiver about 15′ from the transmitter. It is possible to tell what song is playing nearly 6 miles away but understand that your results may vary–that it why I would prefer that the buyer witness it’s capabilities first hand before buying.
Total posts : 45366Radioham posted: “but we arent supposed to have ground radials.”
I am happy to say that you are mistaken.
There is no restriction in the part 15 rules about ground radials.
Perhaps you’re thinking of “ground-leads” that make your total antenna measurement more than 3-meters?
All part 15 stations that have the real-estate to do so tend to have ground radials.
Total posts : 45366And herein lies the umpteen kazillion discussion of ground leads, radials, etc.
The basic problem with all of this is that all we have are a few, simple words on a piece of paper (at least back when it originated) that tells us what kind of antenna system is compliant with Part 15.
These words are open to interpretation, and, in fact, have been interpreted differently throughout the years, both by practitioners and FCC inspectors alike.
Are radials allowed? The rules don’t say anything explicitly. It’s been stated (not by the FCC) that you’re not allowed long ground leads, as they radiate, but again, that’s not explicitly in the rules either.
Are capacitance hats allowed? Not in the rules. And again, differing opinions and potentially differing rulings from FCC inspectors.
So when someone says that, because the directors & reflectors of a beam antenna are not physically connected to the driven element, they are allowed, forgive me if I take this with a grain of salt. They ARE part of the antenna system, and thus, according to the words in the rules, need to be at most 3 meters in length total (including matching element, feedline, etc.). Others may disagree with me, but the fact that people are disagreeing leads us into yet another Part 15 gray area.
Bottom line – it will take an FCC inspector to determine whether ANY antenna system or installation is compliant. All an operator can do is to infer the intent of the rules and do their best.
Total posts : 45366First off the audio on that Rangemaster is awesome. The coverage to really has me scratching my head on that one. Wish I had the land for a mass to actually try something like that because 6 miles is what I would really love to come. And surprise of all surprises no rules had to be broken to get that type of range. I know pirates on FM that would really love to have that type of range. I have a good idea to see what we can do about trying something like that on AM.
Well first I’d have to save $500 and that is just for the TX.
Total posts : 45366I didn’t get nearly that supposed 6 mile range on my Rangemaster.
Not on my ground-mounted one over soil that was highly conductive, or mounted high.
I got 1-2 miles on the ground mounted install, much less up high.
I suspect that something is acting as a long ground lead on that transmitter. The physics and math predict under 2 miles with a great (legal) installation.
Total posts : 45366Hmmm … has ground-mounting become the trend?
I’m curious, how many are engaged in this type of installation… and
does it result in better transmitter performance (compared to elevated
installs) … or is the motivation driven by compliance, perceived or otherwise?
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