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"Low Profile AM Broadcast" Antenna




 
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Author Topic: "Low Profile AM Broadcast" Antenna  (Read 7668 times)
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aa5wg
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« on: May 05, 2012, 10:05:14 PM »

Hello to all:

Check out this link regarding the AM broadcast low profile antenna system.

http://www.star-h.com/Antenna-Products/Low-Profile-Broadcast/index.html

I think using elevated radials would be beneficial.

160 meters would be an interesting experiment for this antenna.

Can anyone say exactly what this antenna is?  And, what is your gut feeling towards this antenna for 160, 80, 40 and the rest?

Chuck
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aa5wg
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« Reply #1 on: May 05, 2012, 10:10:59 PM »

Here is another link:

http://www.kintronic.com/resources/technicalPapers/2.pdf

This link show a directional version of the first omnidirectional link from above.

Chuck
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kb3ouk
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« Reply #2 on: May 05, 2012, 10:15:55 PM »

Just by looking at it, it appears to just be 4 inverted Ls placed so that the radiation pattern would be more omnidirectional. The most complicated part would probably be phasing the 4 elements so that it actually preforms like it should.
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K5UJ
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« Reply #3 on: May 06, 2012, 05:54:26 AM »

I think it's a little bit different.  I downloaded the pdf but it was hard to get a resolution that let me see the feedpoint diagram clearly.  It looked like a top loaded skirt of four verticals (or 4 inverted Ls equally spaced) but it looked to me like it is fed at the top.  It looked like the line from the ATU goes up inside the skirt to the top.

It's probably of interest to lower power broadcasters up near the top of the bc band but for us hams it might make a pretty good 160 m. antenna.  I read that they use it with 120 radials, probably a key factor in its working well.  It's "low profile" compared to a broadcast antenna--you'd still have to have four phone poles to hold up the top hat.  It'd be interesting to see how it is modeled. 

Of course Kintronic isn't exactly cheap so any ham would have to build it himself (unless he has a lot of money to spend).
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R. Fry SWL
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« Reply #4 on: May 06, 2012, 07:12:58 AM »

The four vertical conductors are connected together at their base, and the feedpoint terminals are that common point, and the common point of the ground radials.  The horizontal conductors top-load the vertical conductors, making the current in the vertical conductors nearly constant along their heights.  This raises their radiation resistance, which improves the radiation efficiency of the system.  Net, far-field radiation from the horizontal wires is zero because equal currents are flowing in opposite directions in each in-line pair.

The currents in the four vertical wires are equal and in phase.  The spacing of the four vertical wires is analogous to using a tower section with about that same cross-section dimension -- which improves the VSWR bandwidth of the system.  Radiation from the system is vertically polarized, and omnidirectional in the horizontal plane.

There is nothing "magic" here, just the application of well-known principles given in standard engineering textbooks.
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W4NEQ
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« Reply #5 on: May 06, 2012, 10:53:58 AM »

There is nothing "magic" here, just the application of well-known principles given in standard engineering textbooks.

Amen.  Top loaded vertical.    I think it was McCoy? who built a similar 6 foot vertical for forty meters for a QST article in the 70's



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KM1H
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« Reply #6 on: May 06, 2012, 02:01:40 PM »

That appears to be similar to a 2.4GHz array that I worked on for a microwave internet system that utilized V&H polarities and multiple ports with excellent polarization and segment to segment isolation.

The money was in the 24 port matching network and phasing lines.

Carl
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Jim, W5JO
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« Reply #7 on: May 06, 2012, 03:32:09 PM »

A 5KW (IIRC), 3 tower array in Guymon, OK had 100 or so radials about 4 ft. off the ground to a ring like that about 50 ft. out.  At the ring the radials dropped underground and continued another 50 ft.  That was KGYN at 1210 Bill.  The array was pointed at you and you may be able to hear them.

The station had good coverage but I can't help but wonder if copper thieves have salvaged the radials by now.
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Gito
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« Reply #8 on: May 07, 2012, 05:29:47 AM »

Hai

I think the problem is laying 120 ground radial 1/4 wave long ,that needs a lot of land

Gito
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k4kyv
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Don
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« Reply #9 on: May 07, 2012, 12:21:20 PM »

KinStar has run ads in Radioworld magazine. That was their major selling point: the nationwide proliferation of restrictive zoning regulations and height limitations that make it increasingly difficult to put up a full size vertical monopole in urban areas. I don't think the control freaks have attempted to regulate or prohibit burying wire in the ground just yet. The inflated cost of real estate (and copper wire) are pretty much taking care of that.

Their other selling point was the FCC go-ahead to allow broadcast stations to use the system. Ever since the commission phased out old-style cage and flat-top multi-wire Tee and inverted-L antennas, most AMBC vertical monopoles appear to be well over 45 in height, with the extremely short ones used only in emergency or for stand-by purposes while maintenance is performed on the regular antenna.

WSM has a short tower for this purpose, about 200' tall, at the same site as their 800+ foot Blaw-Knox.
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Don, K4KYV                                       AMI#5
Licensed since 1959 and not happy to be back on AM...    Never got off AM in the first place.

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« Reply #10 on: May 07, 2012, 12:26:40 PM »

I don't think the control freaks have attempted to regulate or prohibit burying wire in the ground just yet. The inflated cost of real estate (and copper wire) are pretty much taking care of that.

I've heard from people currently active in the tower/site business that Ohio will not allow new site ground system buried copper.
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k4kyv
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Don
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« Reply #11 on: May 07, 2012, 12:47:17 PM »

Wonder what the alleged reason for that is (other than exercising control for its own sake).  Certainly not environmental, since copper is one of the more inert metals in reaction with soil minerals... and if this also applies to ham antennas, and what about replacement/repair of existing buried radial ground broadcast station grounds. Copper-clad ground rods and burying copper pipes in the ground?

Is there anything left to regulate, that hasn't already been made illegal somewhere in the USA?
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Don, K4KYV                                       AMI#5
Licensed since 1959 and not happy to be back on AM...    Never got off AM in the first place.

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WA1GFZ
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« Reply #12 on: May 07, 2012, 01:35:30 PM »

stupid idiots don't seem regulated
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