HF antenna's for home use of CAP equipment

[cap235629]

I am the squadron Comm officer and have been contemplating installing an HF unit at my house.  My problem is the same as most, space for an antenna,  I have searched the forums and cannot find any meaningful answers to the following questions.  Hopefully someone else has had the same questions and has the answers I am looking for.

Is there an HF antenna that will work on the CAP HF freqs that is about 50 feet long?

If there isn't can someone tell me how I might construct one?

Has anyone ever tried using a vertical HF antenna for base station use?

Our wing HQ is about 180 miles away, will I be able to contact HQ with a vertical or will the signal skip?

Thanks for your help

[PHall]

Who made the radio and what model is it?

Most of the newer ones can use a vertical antenna with a antenna tuner to keep the SWR down to reasonable limits.

[cap235629]

CAP issued Micom

[♠SARKID♠]

A quarter wave antenna will run you about 50ft, plus a foot or so.  I know there's vertical HF antenna's out there, too.

[RRLE]

An NVIS antenna (cloud warmer) should work at least to 180 miles. It has the advantages of being low and is a generally a wire (read inexpensive) antenna.

[IceNine]

I have the same question.  But, the question really is not will a vert work, but what are some good verts to use?

[desertengineer1]

I just got my MICOM up at the house, and yes, it's a pain.  The biggest challenge was finding a place for the tuner and putting up an antenna that needs minimal maintenance.

I lucked out and found a good length of low-loss heliax.  The MICOM main unit is in a closet in my office, with the remote head on my desk.

I've tried two antennas fed by the tuner - a 33 ft vertical and the long-wire provided with the unit.  The tuner does well with both, but the optimal bands are limited by the parameters of each.

The vertical performes well above 5 Mhz.  I get great links with Andrews and other CAP stations around - if the propigation is agreeable.

The horizontal does better at the lower frequencies, but because it's lower to the ground and sloped, the pattern is rough.  But it's less of an eyesore.

From the main R/T, it goes through 70' of LDF5-50A (7/8" heliax) through the ceiling, along the attic, and down the brick wall corner of my back porch.  When I want to operate, I connect the tuner to the ground and antenna (needs to be within 3' of the ground), and tie it to the 7/8" heliax with another 30' of heliax 1/4" superflex.  It's easy to configure any radio in the back yard with that cable.

At 30 Mhz, the total loss is about 2 dB.

With the Micom, you're stuck with the antenna tuner - unless you have a 3-30 Mhz flat response antenna.  If you are operating at only one frequency, you can forgo the tuner for a traditional 50 Ohm antenna such as a dipole, vertical, or other.

[tribalelder]

1) During daylight hours,  our our *A and *B frequencies are not well reflected by the ionosphere.

2) A dipole for *A or *B  is about 100 feet long.  You can make traps or coils to shorten it, but start out figuring 100+ feet.  60 is about the shortest you can take it down to with coils.

3) At 20 feet about the ground, most of your dipole's signal goes up.  IF the ionosphere is reflecting (actually refracting, but...) *A or *B, you will have good NVIS propagation-a 200-400 mile circle of coverage.

4)  Unlike VHF, HF paths are not reciprocal.  If I can hear you on VHF simplex, there''s a very good chance, assuming like power levels and antennas, that you will hear me.  But, on HF your station may have no 'skip zone' no coverage area (NVIS), but the other stations in your HF net may have skip zones in their transmitted signals.  Hence, even if everybody hears you (unlikely, because HF signal reflwection can be weak) for 300 miles, you can be in someone else's skip zone and not hear their reply.

5)  ALE (automatic link establishment) uses computer controlled HF radios to find and remember open paths to stations in the net.  It will make contact schedules (channel changing by time to find working HF paths) obselete, if/when we get up to speed.

6)  ALE (if/when) may have big appeal to cadets, because text messaging is possible.  Text is robust, and gets through when conditions are bad.  I expect some day to be reviewing ALE HF text messages, trying to figure out what "Godzilla wants a pizza, but the Weasel requires Cheese-its!"  means.

[IceNine]

That is all very informative, but it still doesn't answer the question.

IS there a decent vertical antenna that is not hundreds of feet tall, that will work effectively with the Micom 2's which as I understand it have ALE.

[PHall]

That is all very informative, but it still doesn't answer the question.

IS there a decent vertical antenna that is not hundreds of feet tall, that will work effectively with the Micom 2's which as I understand it have ALE.

Have you tried any of the bigger ham radio places like Ham Radio Outlet?
They usually have access to the info you need so you can tell which antenna will work with your radio.

[desertengineer1]

That is all very informative, but it still doesn't answer the question.

IS there a decent vertical antenna that is not hundreds of feet tall, that will work effectively with the Micom 2's which as I understand it have ALE.

You're asking for a simple answer to a rather complex question.

The MICOM Antenna tuner will properly match almost any antenna with significant length - but "what works" is the complex part.  The antenna has to be able to effectively radiate energy, optimized for the propigation you want to use.

You need to understand HF basics, propagation, and antenna's. 

As I said above, the answer depends on what modes of operation you are planning to use.  ALE will be of no use if you are using a crappy antenna.

Many verticals are available commercially, but you have to understand a few technical basics.  First, most verticals available in, for example, Ham Radio Outlet or amateur radio sources are optimized for specific amateur radio bands - not CAP channels.  You will need an antenna that will radiate at those frequencies - not just tune.  If the vertical's response is a flat 50 Ohms from 3 - 30 Mhz (ulikely), you won't need the tuner.  BUT - I HIGHLY RECOMMEND YOU FIND SOMEONE WHO CAN HELP YOU IF YOU ARE NOT SURE.

If you are unsure or aren't up to speed on HF stuff, use the antenna that came with the kit, per the manual. 

If you're going to use a vertical, the MICOM will most likely need the tuner - and that requires a special terminal, end-fed configuration - which are not normally what Hams use.

We're not fully up to speed with ALE yet, and even the basic operation can get complicated.  Unless you have an HF discone or HOBA available (VERY BIG), we're stuck with the tuner.

I'll take a look at some commercial verticals and try to give a general opinion.  Maybe there's something out there - but it needs to be tested with the MICOM, and that's going to need advanced knowledge.  ALE is a new thing, and we'll be doing a lot of evaluation to find good setups.

A general answer is that the Tuner will match most antennas, but that is only to match the impedance of the 50 Ohm cable at that frequency.  The antenna's radiation efficiency and pattern at a particular frequency will not change as a matter of physics.

More to come...  I'll see what I can find.   

[PHall]

It had taken the Air Force about three years before they got HF-ALE to be almost useful and reliable. And it's still a work in progress.

Usually if we needed to contact "mother" we would use data on IMARSAT. Getting your answer in hard copy was usually much more useful.

[desertengineer1]

It had taken the Air Force about three years before they got HF-ALE to be almost useful and reliable. And it's still a work in progress.

Usually if we needed to contact "mother" we would use data on IMARSAT. Getting your answer in hard copy was usually much more useful.

I was extemely fortunate to be part of a Scope Command project in the Azores.  The system is fully integrated now, with stations all over the globe.  Free messaging, encrypted data, CW and voice are up and running.

The antennas are HUGE, approximately half a football field in area and up to 4 stories high.  Both wide band operation and high gain come at the cost of size - it's a matter of physics.   It's also 4 KW.

I was able to make a connection with the Andews master station with the vertical experiment.  Haven't tried it with the wire antenna yet.  Have not heard any other stations except Marshal Islands.  But will continue to experiment and work out a 24 hour setup.

[desertengineer1]

THIS is what Scope Command uses.  Would LOVE to have one 


(See the pictures)

http://www.lajes.af.mil/news/story.asp?id=123039547

[desertengineer1]

And another site with good pics...

http://www.ustowerservices.com/projects_azores.html

[cap235629]

new info and another question. Over the weekend we set up one of the new HF RDP's with the end feed antenna. Will a 50 foot end feed work if coupled with a tuner with the CAP Micom 2? What kind of range could I expect? In addition to home use this might be the solution for our squadron headquarters.

[PHall]

THIS is what Scope Command uses.  Would LOVE to have one 


(See the pictures)

http://www.lajes.af.mil/news/story.asp?id=123039547

aka "The Elephant Cage".

[SarDragon]

Except the one in Imperial Beach, CA, which, because of its proximity to Tijuana, Mexico, was called the "Bull Ring".

[lordmonar]

Actually this is an elephant cage.

http://ftp.fas.org/irp/program/collect/an-flr-9.htm

The third picture (the one with the white golf balls) is from a base I used to work at....I owned all the antennas you see in the picture.

[SarDragon]

Ah, the memories.

Pat had his FRD-10; the Navy had their FLR-9. Most of the arrays have been closed and dismantled.

[Dracosbane]

It's times like these that I wish my Grandfather were still alive.  Major Don Broden, Springfield, IL squadron (not sure exactly which one) was a Ham guy and comms (not sure if that was his CAP specialty) with a basement full of radio gear.  He was the reason I joined CAP and wanted to be an MRO. 

I was never allowed to touch the radio equipment, until I had my ROA.  I got to actually do so once, and it was a personally gratifying moment for me.

Pardon me for interjecting a completely different subject here.  I just think of him whenever I read anything Ham/CAP comms related.

Back to your regularly scheduled technical radio jargon.