HF Vertical question

devicelab

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So tell me... how does this antenna transmit on various HF frequencies (as low as 2700khz and as high as 22mhz) whilst delivering over 1KW of output power...? Where is the magic sauce in this antenna..?

 

dlwtrunked

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(You mean 2700 kHz and 22 MHz - that is the proper capitalization for both (note that 22 mhz or rather mHz would be 0.022 Hz not 22,000,000 Hz so you really must capitalize the M). Anyway, what is the maker and model number of this antenna? (We need more than the photo.)
 

mmckenna

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The tuner at the base.

But I suspect that top whip is too short to do much good. Looks like a shortened CB antenna. Put something longer up there and it would likely work fine.
 

devicelab

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I suspect that top whip is too short to do much good. Looks like a shortened CB antenna. Put something longer up there and it would likely work fine.
I wonder if this could be a publicity photo and not the real thing... hmm...
 

mmckenna

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I wonder if this could be a publicity photo and not the real thing... hmm...
It ain't Bothell Washington, where the OP says he is, that's for sure.

Looks like some Truck Stop Firestick whip on top.

I have seen ground plane HF antennas like that used at wave height radar sites. But they have an 8 foot or so whip on top.
 

prcguy

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I believe the horizontal whips are configured as cross dipoles with two connected to hot and two connected to ground and one pair of whips favors lower freqs and the other higher freqs. Not sure about the vertical whip but it would probably be to supplement low angle at higher freqs. The antenna tuner is a low power unit and I would be surprised if it handles more than 200 watts.
 

devicelab

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It's the network transmitters that transmit 1Kw. The end-user setups are what are in the picture (I think) and use 125w radios.
Yep good catch. I didn't read that carefully. The local site radios are 125w and the "network" is using 1KW transmitters. Sorry my bad.

UrgentLink utilizes a 125 watt HF radio with Automatic Link Establishment (ALE), which offers an affordable, easy to deploy solution. With the radio on site, you can connect with the UrgentLink network or reach out to other UrgentLink radios, directly. The radios’ small size, low power requirements and lower profile HF antenna provide flexible installation options. No radio operator license is required to use an UrgentLink radio.

The UrgentLink network is built using Collins Aerospace's HF cellular network technology, our 1KW transmitters and hundreds of HF frequencies. HF cellular mitigates propagation issues such as, time of day, ionospheric fluctuations, sunspot, ionospheric perturbations and frequency selection. It automatically selects the best networked ALE ground station to answer an inbound radio call or start an outbound radio call. The state-of-the-art HF-ALE network provides umbrella-like coverage over an extended geographical area providing a significant advantage over traditional point-to-point HF configurations.
 

jwt873

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prcguy

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Its in the clear but they use ALE 3G which might use some text msg functions. I know of an organization in my area that has used the Urgent Link system.


So it's part of a nationwide HF cellular network that's been around for about five years.. https://www.rockwellcollins.com/~/m...ldwide/Brazil/HF-Cellular-Network-CB-001.aspx

I did some searching to see if I could come up with any of the many HF frequencies they say they use. After about 10 mins I came up negative. Anyone know?? If not digital, or scrambled in some way it might be interesting to monitor.
 

Ubbe

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I believe the horizontal whips are configured as cross dipoles with two connected to hot and two connected to ground....
The picture show all four horizontal elements to be connected to the same metal disc. The top whip are offset to the ground disc to be able to have its antenna connector going thru the metal disc and connect to the coax outside of the mast tube. It seems to be one vertical element that does it all. The ground disc seems to have more holes in it to accommodate twice as many ground plane elements.

/Ubbe
 

prcguy

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The antenna is advertised as NVIS so the horizontal whips are active. Its common to have a dipole pair tuned to a low frequency and a second dipole pair tuned to twice that frequency so you never encounter a dipole running at a full wavelength or multiples causing a very high impedance at the feedpoint.

The way I believe this antenna is configured is if you were looking from the top down at the elements you would seen an X. The two elements on the right would be connected to ground and the two on the right would be connected to the hot of the antenna tuner. That would give you a dipole for the lower right to upper left elements and another dipole for the lower left to upper right elements. A vertical whip connected to hot would work against the two grounded elements and would be tuned for a much higher frequency than the dipole elements, so its mostly out of circuit on the lower NVIS bands.

The picture show all four horizontal elements to be connected to the same metal disc. The top whip are offset to the ground disc to be able to have its antenna connector going thru the metal disc and connect to the coax outside of the mast tube. It seems to be one vertical element that does it all. The ground disc seems to have more holes in it to accommodate twice as many ground plane elements.

/Ubbe
 

devicelab

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I did some searching to see if I could come up with any of the many HF frequencies they say they use. After about 10 mins I came up negative. Anyone know? If not digital, or scrambled in some way it might be interesting to monitor.
I've only confirmed these two personally... there are others I'm sure...

4234.0
6335.6
 

jwt873

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I've only confirmed these two personally... there are others I'm sure...

4234.0
6335.6
Thanks.. I continued searching and darned if RadioReference didn't have some info --> ALE Networks - The RadioReference Wiki

There's a link there to this site --> http://www.ominous-valve.com/ale-list.txt which has a bunch of frequencies listed. But doesn't appear to be anything specifically related to the Collins Rockwell HF cell network freqs.

I listened to a few of them while I was doing other things at my desk. Didn't hear anything..
 

devicelab

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There's a link there to this site --> http://www.ominous-valve.com/ale-list.txt which has a bunch of frequencies listed. But doesn't appear to be anything specifically related to the Collins Rockwell HF cell network freqs.
ARINC UrgentLink (Collins Aerospace/ ShipCom)

This is a 2015 commercial venture that seeks to create a
national commercial HF system available to contracting
agencies with no maintenance by the customer. A pilot net
is being established at the Los Angeles County Sheriff
Department. Most frequencies are idle maritime channels
authorized by an FCC waiver intended to allow emergency
communication. The net was used for hurricane relief in
Puerto Rico.

2679.6
2685.0
4234.0
6335.6
7315.6
8085.5
10170.6
13152.0
17287.0
19755.0
22738.0
 

jwt873

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Thanks..

I noticed 10 Mhz was open today. WWV at +20dB.. So I parked on 10170.6 USB and listened. About every 15 to 30 mins I was hearing a brief digital signal. There was nothing else. Out of curiosity I tried a couple more of the frequencies 8085.5 and 13152.0 and heard the same thing on those frequencies as well.

The signals sound somewhat like FAX or SSTV, but are too short to be sending anything like images. I'm guessing that since it's an HF cell network, these signals are used to check the propagation paths on various frequencies so the best frequencies would be used to pass any voice or whatever.

Here's a sample of one of the brief digital signals I was hearing on the frequencies: https://ve4cy.net/audio/101706.wav
 
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