The paper on AM Antenna Engineering, its history and present status, is a full education on the subject starting from the earliest times.
Thank you for sharing such first rate material.
for a guy like me with some knowledge.
In other words, I still have a lot to learn.
This paper is good for that. It's also fun
and has a lot of great history in it.
Bruce, Mon. Stn., CT
What I found that was interesting is that the 1st AM array was in my backyard as WFLA.
We have the history of AM antenna technology but some believe there will be new designs and findings in the future.
For one example, a recent guest on TWiRT (This Week in Radio Tech), talking about ways of solving problems with AM radio in our time, said smaller antennas will be needed because less real estate is available. His present focus is on improving results with Crossfield Antennas, a smaller form with hopeful results.
And, me, only marginally technical, here I am asking the question, "There is no such thing in the universe as a straight line."
You can reply "That's not a question," but is is true and opens a question of how a straight vertical antenna can be considered "natural."
I believe curves need to be designed into vertical antennas and once we manage to do that we might discover that it works better than a perfectly straight antenna.
For that matter we make too many "straight" objects, i.e., walls, floors, windows, sidewalks, beds and chairs.
Some people insist they are straight, but that's not possible. Everyone is rounded and even well rounded.
Watch this forum for resulte on curved antennas.
... You can reply "That's not a question," but is is true and opens a question of how a straight vertical antenna can be considered "natural." ... Watch this forum for resulte on curved antennas. ...
ALL conductors of EVERY physical configuration whereupon r-f current can be made to flow will radiate electromagnetic fields (radio waves).
The only issue remaining is the field intensity that such radiator configurations produce at a given receive location, other things equal.
In the case of groundwaves radiated by medium-wave transmit antennas, this optimum configuration has been shown both by theory and extensive professional experience to be produced by a LINEAR, vertically-polarized radiator.
This is the reason that the FCC requires such for licensed AM broadcast stations, who must generate at least the minimum field intensity for their class of license.
Because of the fundamental principle found by Einstein that all lines in the universe are curved, the notion of LINEAR is a mathematical abstraction.
In physical space the ground radials laying on the earth are CURVED according to the natural turn of the earth's surface.
The so-called linear vertical element is trying to broadcast across the curved surface of earth.
In the case of towers, many aren't straight-edges standing there, they are a tripodal-triangular shape, mostly so they can stand up.
Of coarse there are vertical guyed towers, but I'm suggesting they'd improve in their radiant efficiency if they curved out toward the center and returned to a tip at the top.
The improvement might be barely perceptible given the comparative smallness of man's technology compared to the cosmic scale, but in part 15 we need imperceptible.
i have an idea.
how about a continously linear loaded 3m vertical with a top hat that gets bigger in the middle and is narrow at top and bottom.
put that over a 3m diameter 32 radial ground plane
Continuously linear loaded antennas have come up in the past and most feel that type of antenna does not meet the intent of the 3 meter rule. And, to stick a top hat on it-well...
Personally, I don't have a problem with it.
we can wind it with 660/46 Litzendraht (Litz) wire. wrap that wire around a large 3-5 gallon plastic bucket. use eight 10ft radials on the top hat and eliminate the 3m vertical mast.
i ever get a house with a yard i will try this design out
no room in our present apartment
interesting tuneable loading coil design from NCR website.
http://www.northcountryradio.com/Articles/variomtr.htm
wonder what the "Q" and coil losses are like compared to a standard tapped coil design.
might be good for remote tuneable antenna using a stepper motor and gear reduction.