View Full Version : Antenas
There are many variables in radio communications. However, at the team level only location and antenna construction are controllable by the operator.
Those of you who are in or are about to start SF Communications training, pay close attention. In my experience the basics taught in Training Group worked. I had more success with a 100 ft longwire antenna than most did with their dipoles, parasetic arrays, loaded up buffalo horns, etc.
Below is a picture of an A-team team house in RVN. Notice the typical array of antenas. Some teams buried their antennas. It wasn't that available then, but I should think that PVC pipe would be perfect for burying an antenna.
All antenna stories are welcome. Don't believe everything you hear. The proof is in the Commo!
CommoGeek
04-24-2004, 09:04
One time I was doing a disaster relief mission, sunspots/ solar flux was horrible. We couldn't talk to Miami from St. Augustine on a PRC-104B. That's when the Echo with me showed me how to make a 234-ft. terminated long wire. Miami could hear us fine, but we couldn't hear them until they changed their antenna. What works today may not work tomorrow.....
Building antennas kicks ass.
Team Sergeant
04-24-2004, 10:03
Long shots I usually used a long wire antenna. Intermediate shots I really liked a slant wire antenna. Building antennas is ok, but they don’t work at all if one does not understand antenna theory and wave propagation.
Jack Moroney (RIP)
04-24-2004, 11:50
Originally posted by QRQ 30
[. The proof is in the Commo! [/B]
Now I know I am about to stir up some controversay with this but to me the most important skill for which I ensured all my folks were crossed trained was commo. A team without commo is a highly qualified mob wandering around the operational area without the ability to adapt to changing situations or much of anything else.
I have had the priviledge of working with some of the finest 18Es in the business and if I have learned anything in addition to my appreciation for what they go thru to make commo it is the complexities of the theories and applications they go thru to do it. For those of you that are going to be 18Es you will get excellent training in resonant antennas but the real challenge, which is not taught in SWCs, comes when you have to rely on non-resonant antennas and operations from an urban area. This is a whole new ball game and one which will drive even the best of the 18Es nuts.
Jack Moroney
Für die Sicherheit
What JM says is quite true. However without a thorough understanding of basic antenna theory you will only be lucky once in a while. The term non-resonate or un-tuned is a misnomer. All antennas have to match the impedance of the XMTR at the operating frequency. If not cut to frequency, there are many devices to match the antenna, from a large "Tenna Tuner" which was in the 26-D's, to a bed spring from the old army bunks -- basically 600 ohms. I carried two store bought items in the field. A 100 foot roll of insulated single strand copper wire for my antenna and a small battery operated Field Strength/SWR meter which fit in my shirt pocket. I got them from Radio Shack when Radio Shack actually sold radio supplies.
Non_resonant antennas filled the dumps with hundreds of burned out KWM-2's.
BTW: I am speaking of the time when we still carried the AN/GRC-109 to the field. The 100 ft. wire was specific to the 109. My point remains, pay close attention when radio/antenna theory is taught (presuming it still is).
Jack Moroney (RIP)
04-24-2004, 12:23
Originally posted by QRQ 30
[Non_resonant antennas filled the dumps with hundreds of burned out KWM-2's. [/B] Absolutley true, however I am talking about constructing non-resonant antennas in an urban environment where the use of an antenna tuner is a requirement. Of course this is just one of the accessories we found that were required for successful urban operations that helped load radios into a non-resonnant antenna. My operators also incorporated SWR bridges, low pass filters, AC power line filters, antenna switches, and dummy loads. But then this was sixteen years ago and I am sure technology has advanced to the point where some of this is now redundant. At the time, however, even with seasoned 18Es like yourself, we wrote our own urban commo manual that served as a baseline for urban commo requirements. Still, each operator had a favorite system and seemed always to be able to make commo. And as you pointed out, some of the rigs defied the antenna theories of the day but they still could make commo. Guess why that is why it was called Antenna Theory. Still these guys worked magic and were able to communicate theater atmospheric conditions allowing of course. I learned a lot from them, could never do what they did, but sure had a healthy respect and understanding for what I was asking them to do when I laid out the commo requirements.
Jack Moroney
Für die Sicherheit
froglegz
04-26-2004, 18:26
communications is a lovely thing when it works..... and as the commo guy it was even a bit of mysterious. you could convince the entire team that if they did what you told them to do commo would work... i had an a team + on the roof of a big air force bus waving their arms towards ft bragg from rhode island. no one had made commo in a week of training so when we landed i told them they were pushing the wave toward bragg. i was really just using the bus as a big reflector. but it was magnificent to watch all of these guys waving and waving like they really thought they were doing something. i did get through and was so loud that bragg thought i was some big broadcast stn and ignored me for a time. but the commo gods were with us and stayed with us for the week.
CommoGeek
04-27-2004, 09:54
eyes,
Got your email. Been a little too busy to really write anything up. Did you lose what I sent you when you first went to LRS? Most of that should be fairly basic 31C stuff.
For short shots you can also try an inverted-V with a counterpoise. Half of our shots at JRTC were under 30 miles and we used those and the NVIS with great effect.
eyes - put this in a notebook somewhere for long wire antenna calculations:
1/4 wave antenna divide 234 by frequency
1/2 wave antenna divide 468 by frequency
full wave antenna divide 936 by frequency
that gives you your antenna lengths for each respective wave length.
I found a copy of FM 90-5 that has a chart for calculating antenna lengths in one of the appendix. it is on line all over the place.
also, hit the HAM sites. those guys have all kinds of non-standard antennas (aka field expedient) that they are proud to show you all about.
For a little hip pocket training one day in Korea I had my guys building frames of sticks and then tracing their shapes with wd1 wire and seeing who had the best reception. They couldn't use a design they had ever seen before.
had them building di-poles on sticks and all kind of crazy stuff.
had good luck with a zig zag pattern that made a kind of LPA shape.
better to know that stuff than have an LLVI team humping a DF Antenna bag and an OE-254.
BMT (RIP)
04-28-2004, 03:45
I was working in S-3 7th Gp and one mornig a young E-5 came in to pick-up one time pads for an exercise. We went around to the cyptro room and he signed for the pads and then ask the cyptro O'Chief whats that number you divide into freq toget antenna length'?
BMT
NON-DIT-DAH
CommoGeek
04-28-2004, 09:29
Originally posted by eyes
Another thought: USASOC could come up with a 1 week course similar in to the conventional "Combat Commo" course and call it "Special Operations Commo". The cadre would be BTDT 18E types, making it similar to the MACV Recondo school do to the fact that their would be BTDT SF types giving a very extensive crash course to a bunch of high peed / hard chargen LRS types. (and whom ever else USASOC and/or SOCOM deemed worthy to attend...)
Whom better to share this knowledge with and whom better to teach it...
This is sort of done with the modern day Recondo school [RSLC] that 4th RTB runs but I think a more condensed version completely focused on commo would be a huge asset to not only commo guys and RTO's in a LRSU but the like in the 75th, 160th, SOT-A's… The information is decimnated basically OJT / word-o-mouth now but I still think a formal course would be a huge step in a positive direction.
Thoughts?
This is done to an extent, it is the Special Operations Communications Systems Operators Course. SOCSOC is actually the old SF Base Station Commo course. There is a maintenance course as well, SOCSMC.
Before you get too exited, the above covers SF specific commo and I'd venture a very educated guess that LRS doesn't have the gear taught in SOCSOC. SATCOM maybe, but HF? No way.
Maybe your training NCO could swing something with a SF company so they could practice their UW/ FID skills? Problem is, your unit would probably pick up the tab for it so that may stop that notion altogether.
I'll get with you offline about this later this week if you'd like. Comparing your commo requirements with that of USASOC units shouldn't be done via the internet.
I saw WD-1 mentioned as antenna wire. I recently saw a high ranking commo chief at Ft. Bragg mention base station antennas constructed of WD-1. Gentlemen, WD-1 is easily available but, IMHO, is one of the least desireable wires available for radio antennas. It is a poor conductor of RF energy. It is constructed of multiple strands ofr copper and steel. The steel is for strength.
Radio frequency travels along the surface of the conductor and not the core. IMO a single strand copper wire is best. You can buy this in Radio Shack and other sources. Get it insulated, preferably with a neutral color insulation, depending upon the terrain you will operate from. In Germany we were issued single strand copper wire for the AN/GRC-109. It was a terrific antenna but was insulated with a clear lacquer, Few were lax enough to use it and if they did they were usually "scarfed up" since the antenna resembled a shining mirror in the light.
I have lots of experience in clandestine HF and FM communications. This incluced working from within buildings. If any are interested I may drop a little tid-bit when the formu gets slow. :)
Roguish Lawyer
04-29-2004, 15:47
OK, QRQ:
I would like to understand why my cell phone works in some buildings but not others, and what if anything I can do to improve reception inside of large buildings.
I obviously have an idea, but I would like the real scoop from an expert.
:munchin
Oh, the fool I would be not to listen those who have come before me, as I have only begun to learn. Feel free to impart wisdom as I do not know what I do not know.
RL: Micro waves are easily attenuated by heavy mass such as reinforced concrete, metal construction, etc. About all I could suggest is to continue to move around until you find a suitable place. An external antenna may also work. Cell phone range is limited and depends upon the number, location and orientation of the towers.
Recently some people blocked the construction of an "unsightly" tower in their neighborhood. Not too long ago one of thos people was complaining of the very problem you mention.
Originally posted by QRQ 30
I saw WD-1 mentioned as antenna wire. I recently saw a high ranking commo chief at Ft. Bragg mention base station antennas constructed of WD-1. Gentlemen, WD-1 is easily available but, IMHO, is one of the least desireable wires available for radio antennas. It is a poor conductor of RF energy. It is constructed of multiple strands ofr copper and steel. The steel is for strength.
Radio frequency travels along the surface of the conductor and not the core. IMO a single strand copper wire is best. You can buy this in Radio Shack and other sources. Get it insulated, preferably with a neutral color insulation, depending upon the terrain you will operate from. In Germany we were issued single strand copper wire for the AN/GRC-109. It was a terrific antenna but was insulated with a clear lacquer, Few were lax enough to use it and if they did they were usually "scarfed up" since the antenna resembled a shining mirror in the light.
I have lots of experience in clandestine HF and FM communications. This incluced working from within buildings. If any are interested I may drop a little tid-bit when the formu gets slow. :)
I've always liked to use claymore wire for my ant.
Radar Rider
05-04-2004, 06:26
I'm goin' with Eyes on this one. Long haul communications are dependent on a long wire. What it takes to get there and what one may use is certainly mission dependent. Even working with the -43 and the -137 require some knowledge of antenna theory.
Even in 2004 (ESPECIALLY in 2004) no comms are guaranteed. While IMC has fallen by the wayside, I will always advocate that it be taught and learned. Satcom is great, but if it goes out, we still need a backup. PACE!
A good start for learning theory and practical construction is the :"ARRL Antenna Handbook". Pay attention to the "lobes". You will find that with a 3/4 wave inverted "L" antenna, the maximum radiation is 60 deg. off of the end rather than broadside.
Originally posted by Radar Rider
I'm goin' with Eyes on this one. Long haul communications are dependent on a long wire. What it takes to get there and what one may use is certainly mission dependent. Even working with the -43 and the -137 require some knowledge of antenna theory.
Even in 2004 (ESPECIALLY in 2004) no comms are guaranteed. While IMC has fallen by the wayside, I will always advocate that it be taught and learned. Satcom is great, but if it goes out, we still need a backup. PACE!
KALUA OFF-CENTER (aka The KOC)
There is no reason to string that much wire for the -137 ALE. Match the impedence of the radio with 30 feet of ladder wire. String 36 feet of wire off your positive end and 18 feet off your negative end. This length has been calculated to specifically match the impedence of the radio. Adjust height as needed.
QuietShootr
05-04-2004, 09:24
There is a lot of good antenna stuff available in the ham world, if you sift the bullshit out. As stated above, the ARRL has some good handbooks available..check out ARRL.org.
QS(KB9xxx)
froglegz
05-04-2004, 19:02
they also used to have loads of antenna construction projects for limited space applications... urban dwellers and the like.
some of the older handbooks have some stuff that is now considered outdated but still good ideas and maybe they will have a special application for our world...
still gotta love that code ...
.. .--. .-.. . -.. --. . .- .-.. .-.. . --. .. .- -. -.-. . -
--- - .... . ..-. .-.. .- --. --- ..-. - .... . ..- -. .. - . -.. ... - -. - . ... --- ..-. .- -- . .-. .. -.-. .- always and forever!
The Reaper
05-04-2004, 19:36
Originally posted by froglegz
they also used to have loads of antenna construction projects for limited space applications... urban dwellers and the like.
some of the older handbooks have some stuff that is now considered outdated but still good ideas and maybe they will have a special application for our world...
still gotta love that code ...
.. .--. .-.. . -.. --. . .- .-.. .-.. . --. .. .- -. -.-. . -
--- - .... . ..-. .-.. .- --. --- ..-. - .... . ..- -. .. - . -.. ... - -. - . ... --- ..-. .- -- . .-. .. -.-. .- always and forever!
You guys would have to see how fast Jerry here could copy that stuff. He was one of the very best.
Pretty quick with the key as well.
Don't make me get out my tri-graph card!
TR
QuietShootr
05-04-2004, 19:37
.- -. -.. - --- - .... . .-. . .--. ..- -... .-.. .. -.-. ..-. --- .-. .-- .... .. -.-. .... .. - ... - .- -. -.. ...
Sinister
05-06-2004, 19:54
Agree that ARRL (American Radio Relay League) has great resources in the Amateur Radio Handbook and their antenna resource books. You can find them in the post library. It even works with 137s and ALE.
I went to every Team house we had in Haiti and you could tell who had the squared-away commo dudes. They were the ones who had their HAM licenses and made regular commo back home to CONUS through HAMs and MARS (who would handle radio-wire interface calls to the house).
You could see it in their antennae and battery/power set ups, from verticle loops to you-name-it. Some teams couldn't make comms to get fed, and they were less than 100 miles away from their B-Teams.
We've got all this high speed real-time push to talk comms from SHF to SATCOM, INMARSAT, and Iridium, yet you can still do discrete dit-dah on low power HF with a good antenna when some command above you pre-empts you or puts you on quiet time.
froglegz
05-06-2004, 20:50
amen my friends... i may leave america for short periods of time but i will always come back, and when i hear the star spangled banner it will always bring a tear to my eye.
like dorothy saud, "there is no place like home!"
thanks tr, from one whom i respect, that means a lot.
i still listen to tapes once in a while and i have a stack of trigraphs i just ran across.... want one????
I have had men tell me they used slinkies as antennas for the PRC-74. Does anyone else have some practical inventions which are quick and easy?
CommoGeek
05-22-2004, 09:29
I know of two Echo's that made commo from Tampa to Miami with PRC-127's and slinkys. It rained the night before so they got a good ground wave through the 'Glades.