Why not build the classic 3 meter base loaded antenna with ground radials the side where you want the signal to point most of the energy, then measure out spacing from the middle the same length of the driven element? Put a slightly larger element behind the driven element at 3 meters, place another element in front of the driven element which is slightly shorter than the last two elements.
The only part of the antenna that would be energized is the middle element, the other elements would be a director and reflector.
The front non driven element would be the director, the rear non driven element would be the reflector. Those two added elements while technically not part of the transmitting antenna, should work much like a beam antenna. It would take some patience to set this system up , but i don't see why it wouldn't work.
What i don't know is the exact spacing needed to make the added vertical elements work with the powered element. All beam antennas use a dipole as the driven element with hot on one side, ground on the other. In this case the earth is the ground side of the system.
Both the reflector and directors need to be isolated from Earth ground but spaced far enough apart to become effective, that's where patience comes in to play. Spacing makes or breaks a good beam system.
Take a look at ANY commercial AM station antenna.
touche 🙂
LOL!!
we are fooling ourselves into thinking your getting a foot out of anything other than line of sight because your not using skywave your not propagating a couple hundred miles you're not basking in a nvis straight up and down 25 mile coverage here we are line of sight depending on what's in your way and what's not in your way and reading all the results of what most are getting anyway 1-2 miles at most I would add take your transmitters up a tall tree and see how much farther you get it should surprise you esp your using a pro-caster or Rangemaster they are best things going basically mediumwave walkie talkie transmitters..
JOE THE RADIO DOOD
I just realized that I've been a member of this site since 2010, but don't think I have ever posted. I read the mail from time to time, but don't comment. Anyway, after reading the above post by Joe, I felt the urge to say a few things about ground wave and line of sight propagation.
Ground wave propagation happens with signals up to about 2MHz. The electro-magnetic waves from the transmitter induce currents in the earth. As a result, the wave tends to follow the curvature of the earth. Obviously, with the range of a low power Part 15 signal, there won't be a whole lot of curvature, but the fact that the ground is an important part of propagation at this frequency remains.
With line of sight propagation, the wave travels directly between transmitter and receiver in a straight line. The earth is not involved in the mechanics of this type of propagation. It is distinctly different from ground wave propagation.
I don't know a whole lot about propagation, and am learning as I go, but I'd say that Joe is definitely correct about the fact that our low power AM part 15 signals don't reach the ionosphere, which rules out any kind of sky wave propagation or NVIS. Unlike FM Part 15 though, where the only propagation mode is line of sight, our AM signals rely heavily on ground wave propagation for any kind of meaningful range.
Unfortunately, that means we need good connections to ground. Better get pounding those ground rods and/or burying those radials!
PS - sorry I haven't introduced myself, but I probably won't be posting here a whole lot.
AM MW Radio is not "LOS." It follows the earth's curvature during the day and Skywave at night.
Okay ... 'Plan-C' is now operational and with astonishing results. I use the word 'astonishing' because for me, it accomplishes what has always been my primary objective, and that is to serve a small community, group or neighborhood with my legal Part-15 station.
Since most seem to be in agreement that outdoor elevated installations could warrant a visit and/or an NOUO from the enforcement bureau .. and since my two attempts at ground-level installs were a disappointment in terms of desired range, 'Plan-C' was simply something I felt compelled to try.
My Rangemaster has found a new home ... under shelter. The transmitter now resides on the inside of a garage .. as the structure provides ample headroom for the 8 ft whip.
Some immediate advantages are as follows.
1. The transmitter is no longer exposed to the often-harsh outdoor elements of the brutal northeast.
2. The cover of the transmitter's enclosure can be permanently removed, exposing the 100 milliwatt LED for anytime compliance monitoring.
3. The audio/power cable length has been reduced to a mere 10 inches total ... leaving over 12 inches to spare all-the-while staying well within the 3 meter restriction.
4. And for what it's worth, the unit is less susceptible to a direct lightning strike and potential vandalism.
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As mentioned in a previous post, my configuration utilizes a wireless STL, meaning there is no direct physical connection between studio and transmitter. This allows for the much shorter (10") feed line ... greatly diminishing the likelihood of any measurable stray and unwanted RF emitting from the cable.
The transmitter is now connected directly to the household's service ground... right at the outlet box. This DID effect overall range... but not as much as I have been led to believe. After all, in most cases, the ground lead is connected to a network of buried cold water pipes.
On the inside, the 8 ft stainless steel antenna reaches the rooftop. If I can devise a foolproof method for preventing leaks, I might consider protruding the antenna through the ceiling by a few inches ...so it could radiate into open space. This would require careful planning and might actually offer some improvement.
INITIAL PERFORMANCE RESULTS:
( Reception In The Car)
1. Detectable signal at 3.5 miles.
2. Listenable signal at 2 miles.
3. Minimal noise floor at 3/4 miles.
4. Solid, zero noise floor interference at 1/2 mile.
(Indoor Reception)
Confirmed by three of my go-to neighbors for whom I can rely upon for an honest reception report.
All reported an IMPROVEMENT in the signal, stating it was noise free and solid at distances of 1/4 mile and less. One individual who claimed her light dimmer switch would often interfere with my signal, indicated that this was no longer an issue.
So ... what can be derived from these conclusion? First... they are inconclusive and need further testing and scrutiny. Factors such as direction of travel, weather and atmospheric conditions, man-made interference (power line congestion etc) along with time of day and time of year are all variables that are subject to change.
However, I am impressed and excited by the indoor reception results thus far. It appears indisputably that my effective near-field range has improved. Ultimately, my goal (stated in paragraph one) is closer to being realized. In this process, I'm trying not to be overly concerned with reception at the fringes... where few are likely to interact with my micro-station anyway....given the countless alternatives at their disposal.
Based on the aforementioned observations and for the sake of conversation, I believe it is safe to say that my range in the far-field has been reduced by 15 to 20% .. which should come as no surprise. On the other hand, the near-field range has experienced a dramatic improvement ... for reasons I've yet to fully comprehend.
Again, depending on what it is YOU are personally trying to achieve ... Plan-C may or may not be for everyone.
I like to be the first guy onboard to say congrats on an awesomely engineered station, sir! May you serve your community well.
PS
I too get the same or a little better radius being outside in the elements so I concur wholeheartedly raising the antenna to 35 ft made me all the difference and no grounding at all..:) God SPEED on your upcoming programming keep us informed Bill!!
Radioham
There are a lot of cool folks on this forum and i love all the heated stuff we say hey we are all pioneers here
Radioham
Responding to Dave Richards comment: "I'd say that Joe is definitely correct about the fact that our low power AM part 15 signals don't reach the ionosphere, which rules out any kind of sky wave propagation."
That is true based on something I read a couple years ago in either an engineering or amateur radio source:
The minimum power needed to achieve skywave reflections is about 20 Watts.
So turning an am radio will increase its sensitivity most people forget to tell their audiences to turn their radio for better signal reception. That in mind we have several ways to our user's receivers and as i mentioned line of sight does apply as well as groundwave and reflection/refraction off objects like roads/powerlines/rivers/railroad tracks all are sources of pickup for signals below 2mhz and lastly good old fashioned straight line propagation which in my opinion is the source of our signals best reception reports ALSO ROADS built with rebar are excellent propagators as well...
😉 Radioham
Radioham