Dutch Long Wire
 

OK I've used the search function so hopefully this isn't posted somewhere or I'll drop and do 50....

I'm currently an RTO with a LRSC and next month I'm doing a pretty long commo shot (about 2,000 K). I've have had great guidance from teammates and the LRS manual, but I've never done a shot more than 20 K so this makes me somewhat apprehensive. My questions is this: will a dutch long wire work out to that range? And if so, will standard commo wire work or should I 'liberate' something better from the commo tent? Im using the 150 for HF comms...

I've got the LRS manual, some ancient text on commo (circa 1984 but still useful), and slideshows from LRSC.... but nothing on the long wire. Any experience with it?

1984....ANCIENT....???

Ok, I'll skip that for now...but we'll come back to the whole "Ancient" thing. I'm just glad you were able to translate the hieroglyphs... ;)


Antenna selection is key only in the respect that certain designs will provide you with the correct direction (primary lobe) and the correct take-off-angle (based on the installation and height above "ground"). Frequency selection has more to do with the success or failure of a sky-wave shot. If you have been working in-close at 20k or so, this could actually be an easier link to establish, but if your frequencies are not compatible then life will become immediately frustrating.

It appears you have some time to do deliberate planning. Given that luxury the slicks on your antenna should provide you with the primary lobe and take-off angle based upon height above ground. Take some time to become familiar with those characteristics.

In the "ancient" past I have used long wires or terminated, sloping-V antennas to a great deal of success. These were "cut wire" antennas as opposed to kits, but building a resonant antenna increases your efficiency.

Summary: Do your homeowork (sounds like you started) and get with your spectrum manager on how the propogation models worked out.

Any more of you "ancient' HF guys have a nickle for the machine? :D

Albeham, I know you are out there...

R10

Well it's nice to see one our RTO's doing their homework.

Just to add some information, this HF shot between AP Hill, VA, and Indiana will be done using ALE (and maybe 3G ALE), and it is unclear what control we may or may not have over frequency selection.

To be tactful, we have had varying degrees of success with the frequencies selected in the past by whoever it is that is supposedly doing this for us (the S-6, I suppose).

That said, there is a lot of effort being put into this to make it successful.

To the original poster, keep doing your homework, try searching on this site for "PRC-150", check with your TL as to what materials may be available to make your antennas, since that may affect your choice of what to build. If time and materials allow, my suggestion would be to be prepared to build several different antennas, as Ret10Echo suggested, that should include a long wire and terminated sloping vee. Plan on conducting an LQA with each antenna and recording all the relevant information to include the LQA scores on each freq, time of day, antenna type used, etc.

Recording all this information will allow you to look at what frequencies worked best, which antennas worked better, etc., and start to build your toolkit of what works.

Ah . . . The old days with half-rohmbics, dipoles, 17% off-centers, etc.

I'm not sure that I've ever heard of a "Dutch Long Wire." We didn't use it with the old AN/GRC-109. I know it looks "ancient" but it was a great radio (unless you were the LT who was cranking the generator. :D

A definite challenge having an ALE net that has stations at varying distances. It becomes a challenge to build an antenna that will meet multiple frequency requirements. Most of those fixed stations will have a multiband array of some size. Not so easily reproduced by the tactical operator.

I'm pretty sure I understand what you are saying here... at least the basic gist.

As it applies to the COMMEX that we are planning, this will be an HF link between two fixed stations, both using PRC-150's, and more than likely both using a field expedient antenna system.

MY admittedly limited understanding is that the issue of using a fixed length tactical antenna in a multiple frequency application is at least partially overcome by the internal tuning coupler in the 150. What I have been taught is that the tuning coupler is capable of electronically shortening the antenna length (but not lengthening), so a good compromise expedient antenna is a 1/4 wavelength of your lowest planned frequency (in this case, about 75', 1/4 wavelength for appx. 3 Mhz).

Again, my limited understanding is that the advantages of an ALE net outweigh the possible disadvantages of using one fixed length antenna for multiple frequencies.

I look forward to hearing some corrections or further enlightenment on the subject.

What is a Dutch Long Wire?

Well when you are born in '87, anything prior seems that way ;)


This is what I have been taught as well. Using a long wire during insertion would be much more preferable to a long whip or cut-wire antenna, due to the time factor. Throwing out a piece of wire and rolling it back up is just plain easier.

In the hide site I will definitely try constructing different types of antennas and doing an LQA on each. Thanks for the tips, I look forward to any more advice. Good to see some C Troop guys on here as well.

Hello, here is what I think...

Get with your S-6 shop and talk to your Spectrum Manager. See if you can see or find out what freqs you are going to load in the rig for the ALE group.

Then like the one gent said, but to add, have a good dipole designed for the lowest freq. And get it up about 30 to 45 foot above. I know I am going to get told it should be a 1/4 wave up, I know but, do you have trees like that?

I also would try a end-feed-long wire. It will need to have at least a 1/2 wave cut for the lowest freq. The long wire is good for multi-band work by using harmonics, you can get the radio to use it in a efficient manner. Between the tuner in the radio and the wire it should give you a good usable antenna.
ARRL antenna handbook. Please look it up.

The long wire has no feed line, coax ,ect. It is feed strait from the radios antenna jack, and then pointed about 10 to 20 degrees off center, the direction you are going to shot this hf signal. Ground your radio with a small ground rod, 8" to 9" . Remember strait form the antenna jack, the little small middle point at the BNC jack. A small run of coax, 5", cut and strip it so there is a braid and a center conductor exposed. tie, wrap, etc, the center conductor on the wire, and the braid to the ground rod. The antenna is going to be long and it will need to be supported by a tree / pole etc and the end. Go up from the radio about 10 to 20 feet, then the rest strait out to the world. You could also add a ground wire to this, by running it along the ground under the other wire, this will help the antenna system. Be mind full here, you don't want to have the radio holding the weight of the antenna, you might want to use 550 cord tied to the antenna wire, then tie it to a good solid point so there is no tension on the radio.

Now if I loss you please ask.

Hope the Commo Gods smile on you. Remember Ground the radio!!!!!
:munchin

BT AR

S6?
 

Not much about a Long wire that I don't know - used it almost exclusivly with the 109 - but one thing I don't, apparently, know about is S-6. When did that function come to be? I assume that that it is "Signal." So is the Signal Officer now called the S6?

Just learning something new everyday.

Use to call it the C&E Shop, then the S-6 thing came to play due to the other S-shops.

Al

Google VOACAP, it is a very good HF propagation program. Input the locations of where you think you will be and where you think the other end will be. The software will also ask for current solar flux, transmitter power, and some other variables. After running the program, look at the MUF, LUF and FOT lines.

The frequencies that the S-6 gives you should be near the FOT line for the time periods that you plan to communicate on. If the frequency plan is not executable, then no amount of dutch longwire stuff will work.

The freq plan must be workable. Unfortunately, most freq managers are bean counters.

Antenna Propagation
 

The text may be old, but the math doesn't change. You can have the best transmitter in the world, but if your antenna isn't cut right, you just ain't talkin' to no one, Especially with dipoles and inverted vees. Not sure about the Dutch Long Wire, though.

I was in before Gore-Tex too.

Trail and error. Figure out what works and what doesn't. Whats the goal here, to conduct a commex or a hide with comms?

Given time and materials it should not be that hard. When we went to Ft Smith for the 18E commex my partner and I took plenty of claymore wire with us to augment the gra-50 that we had. We ended up building a 150' Half Rhombic antenna. Another buddy had a General Ham license and we worked the whole eastern seaboard and as far west as Hawaii with a PRC -104.

Sloping V-s were my favorite to use and made hitting Bragg easy. When we set that monster antenna up though, The guys at Bragg's ears were ringing!!!!

Training should be training, work with what you have and try as many configurations as time permits. Take good notes. Apply the math and make adjustments as necessary. Sometimes small adjustments to the angle will pay off huge dividends. As long as you know the principles you should be okay.

I think this may be our biggest challenge. I'll reserve judgment on whether we will get a workable freq plan for now, but I am not optimistic.

This is meant to be a COMMEX. The PRC-150 is still relatively new to our unit, and I believe that this is the first time we are attempting a skywave shot with them. With the right preparation and planning, this could be a great way to introduce our younger and more inexperienced soldiers to building antennas and getting good HF comms. Without good preparation and planning, well...:munchin

As an aside, I believe the "Dutch" long wire is just some strange nomenclature specific to this unit. Who knows how these things get started.