Crossed Field Antenna Test

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Dave Loudin
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Crossed Field Antenna Test

Post by Dave Loudin » Wed Jan 11, 2012 1:41 pm

An experimental authorization (application here) was issued today for testing a new antenna from Crossed Field Antennas that they are calling the CFA Mk II (dimensions in the application). Parameters: 100 w on 1630 kHz at the transmitter site of WGFP, Webster, MA. To avoid having to put in filters, WGFP will go dark while the test transmission is radiating. No mention of detuning the 940 kHz radiator, though.
What's that do....?

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RGORJANCE
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Re: Crossed Field Antenna Test

Post by RGORJANCE » Wed Jan 11, 2012 2:04 pm

Am I having still another senior moment???? I thought it had been demonstrated several years back that they don't deliver the radiation efficiency and coverage that the proponents claim.

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Deep Thought
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Re: Crossed Field Antenna Test

Post by Deep Thought » Wed Jan 11, 2012 2:05 pm

Bob...doesn't keep 'em from trying to get a few more rubes into the tent...
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Dave Loudin
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Re: Crossed Field Antenna Test

Post by Dave Loudin » Wed Jan 11, 2012 2:36 pm

Maybe we'll see another anti-skywave antenna, then? :)
What's that do....?

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Dave Loudin
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Re: Crossed Field Antenna Test

Post by Dave Loudin » Wed Jan 11, 2012 10:38 pm

Well now. All the application says is that 940 uses an ND tower and that this experimental operation will not share it. You don't think that this is a CYA exercise???
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Deep Thought
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Re: Crossed Field Antenna Test

Post by Deep Thought » Wed Jan 11, 2012 10:50 pm

I could call Charlie and ask... 8)
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NECRAT
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Re: Crossed Field Antenna Test

Post by NECRAT » Thu Jan 12, 2012 3:48 am

This site is about 40 minutes from my house. Curiousity has got the best of me now, so I may to take a road trip on Saturday to see what I see.
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Re: Crossed Field Antenna Test

Post by Kelly » Fri Jan 13, 2012 10:13 am

Years ago I tried to build one of these antennas that would work on 160M, but could never get it to load up properly. The matching network required is a nightmare and the bandwidth plus efficency worse than trying to load a Folgers Coffee can. I believe that one attempt at defying physics with this design is still sitting somewhere behind the garage at my Seattle home.
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RGORJANCE
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Re: Crossed Field Antenna Test

Post by RGORJANCE » Fri Jan 13, 2012 11:37 am

I loved the Folgers Coffee Can anology. Which brings me to a slight diversion of the subject. "Back in the day" when beer cans were made of real steel, there was the "Beer Can Vertical". I built one. I lived in Tulsa and one of our neighbors just happenred to be a "non drinker of religious proportions". She complained to my dad, who was not an abstainer, and that resulted in the vertical remaining vertical, with all it's various logos in full view. We made certain that the beer cans were empty prior to soldering them end to end.

Back to subject.

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Dave Loudin
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Re: Crossed Field Antenna Test

Post by Dave Loudin » Fri Jan 13, 2012 2:35 pm

Kelly wrote:I believe that one attempt at defying physics with this design is still sitting somewhere behind the garage at my Seattle home.
Maybe I should try this, because, as Bugs Bunny said, "I never studied law."
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Re: Crossed Field Antenna Test

Post by NECRAT » Sun Jan 15, 2012 1:05 am

I visited the site today, and found out my friend was mistaken on the operation there.
There is a long wire being used for 940. However the CF antenna with the name plate WX1CFA sits where the old tower once sat.
There is a big cinder block building way out in the corner of the property, where I could hear the audio of 940 coming from inside it.
The CF antenna sits next to the main studio location there.

Image

Image

And the long wire setup

Image

Image
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Deep Thought
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Re: Crossed Field Antenna Test

Post by Deep Thought » Sun Jan 15, 2012 12:30 pm

Interesting for two reasons. First, there is no active STA (or evidence of one ever being filed) for that longwire antenna. Second, if the CFA is at the location of the old tower, then there is probably still a ground system under it. Wanna bet this contraption is tied into it?
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Re: Crossed Field Antenna Test

Post by BroadcastDoc » Sun Jan 15, 2012 2:12 pm

It almost looks as though the base of the old tower is directly under that platform.
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Re: Crossed Field Antenna Test

Post by R. Fry » Sun Jan 15, 2012 5:15 pm

Even if the radiation efficiency of this "CFA" setup included the typical ~ 2-ohm r-f ground loss of 120 x 1/4-wave buried radials, its radiation resistance and FCC efficiency would be less than that of an unloaded 1/4-wave monopole -- because the overall height of the radiating conductors including the conductors leading up from the common point of the buried radials is significantly less than that of an unloaded 1/4-wave monopole.

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davedybas
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Re: Crossed Field Antenna Test

Post by davedybas » Sun Jan 15, 2012 6:34 pm

The dang thing looks like the "monkey bars" my kids used to play on.... :lol:

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