Walk me through building me first antenna!

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Redshirt
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Walk me through building me first antenna!

Post by Redshirt » Fri Oct 03, 2014 12:33 pm

Ok, pretend I'm completely ignorant. Run with the idea that I have a HF radio, some speaker wire, a soldering iron that I've used once, and an adapter.

Oh, and a technician license.

Now how the heck do I build an antenna? I'd like to try and get on the 10m band. Things I don't understand from the basic reading I've done.

I just cut some wire, attach it to a connector, throw some silly putty on the other end? Do the wires on the end touch or no?

If I don't want a portion of the wire to radiate (I want a wire to an antenna, for example) how do I accomplish that?

What measuring tables should I keep handy to figure out what band I'm building an antenna for?

Is the square office ceiling I have a good idea for putting up a square antenna in my apartment on the top floor?

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SCBrian
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Re: Walk me through building me first antenna!

Post by SCBrian » Fri Oct 03, 2014 12:46 pm

Redshirt wrote:Ok, pretend I'm completely ignorant. Run with the idea that I have a HF radio, some speaker wire, a soldering iron that I've used once, and an adapter.
Speaker wire sucks, you lose to much. Look at things like RG8X...

Oh, and a technician license.

Now how the heck do I build an antenna? I'd like to try and get on the 10m band. Things I don't understand from the basic reading I've done.

Plenty of plans out there for antennas, find one within your skill. - I build a copper J-Pole last night and an about to put together a slim jim. Most plans are pretty straight forward. Many are optimized for the freq you will be transmitting on. Remember your privileges are limited on 10m with a technician. You can only transmit voice SSB from 28.3-28.5Mhz


I just cut some wire, attach it to a connector, throw some silly putty on the other end? Do the wires on the end touch or no?
More or less, Solder is your silly putty so you can make an electrical connection.
If I don't want a portion of the wire to radiate (I want a wire to an antenna, for example) how do I accomplish that?

What measuring tables should I keep handy to figure out what band I'm building an antenna for?
Depends on the antenna, different antenna types have different measurements

Is the square office ceiling I have a good idea for putting up a square antenna in my apartment on the top floor?
Never dealt with a square antenna - so not sure. if you keep it away from metal it should work ok, but you will loose some gain from being inside.
Here is a basic article on antennas...
https://www.arrl.org/files/file/Technol ... 683033.pdf
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TacAir
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Re: Walk me through building me first antenna!

Post by TacAir » Fri Oct 03, 2014 12:52 pm

Or spend a few bucks....

http://www.ebay.com/itm/like/111469081255?lpid=82

Under 9.00 and another 5 for shipping. Includes a SO-239 (UHF) connector and wire ant w/center support.

So, run coax from rig to antenna, talk.

or

build a vertical from some conduit.
http://www.iw5edi.com/ham-radio/?10-meter-dipole,140
TacAir - I'd rather be a disappointed pessimist than a horrified optimist
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SCBrian
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Re: Walk me through building me first antenna!

Post by SCBrian » Fri Oct 03, 2014 12:55 pm

Examples of the antennas I put together last night:L

http://www.hamuniverse.com/jpole.html

http://www.w4cll.com/m0ukd.htm
I tilt at Windmills
BattleVersion wrote:For my Family?...Burn down the world, sure... But, I'm also willing to carry it on my shoulders.
raptor wrote:...I am allergic to bullets;I break out in blood.
jnathan wrote:... you can choke on my Hebrew National.
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SCBrian
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Re: Walk me through building me first antenna!

Post by SCBrian » Fri Oct 03, 2014 12:56 pm

TacAir wrote:Or spend a few bucks....

http://www.ebay.com/itm/like/111469081255?lpid=82

Under 9.00 and another 5 for shipping. Includes a SO-239 (UHF) connector and wire ant w/center support.

So, run coax from rig to antenna, talk.

or

build a vertical from some conduit.
http://www.iw5edi.com/ham-radio/?10-meter-dipole,140
Wow, he's gotta be losing $$ on that. unless he got a heck of a deal on the SO-239 ?
I tilt at Windmills
BattleVersion wrote:For my Family?...Burn down the world, sure... But, I'm also willing to carry it on my shoulders.
raptor wrote:...I am allergic to bullets;I break out in blood.
jnathan wrote:... you can choke on my Hebrew National.
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TacAir
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Re: Walk me through building me first antenna!

Post by TacAir » Fri Oct 03, 2014 1:01 pm

SCBrian wrote:
TacAir wrote:Or spend a few bucks....

http://www.ebay.com/itm/like/111469081255?lpid=82

Under 9.00 and another 5 for shipping. Includes a SO-239 (UHF) connector and wire ant w/center support.

So, run coax from rig to antenna, talk.

or

build a vertical from some conduit.
http://www.iw5edi.com/ham-radio/?10-meter-dipole,140
Wow, he's gotta be losing $$ on that. unless he got a heck of a deal on the SO-239 ?
Can't say. Just looked to be as cheap as buying the parts and trying a DIY with no idea of what's going on.

Should you do it yourself? Sure, but if your clue bag is empty - kits or ready made make better a 'better' deal until you get some experience....
TacAir - I'd rather be a disappointed pessimist than a horrified optimist
**All my books ** some with a different view of the "PAW". Check 'em out.
Adventures in rice storage//Mod your Esbit for better stability

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CitizenZ
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Re: Walk me through building me first antenna!

Post by CitizenZ » Fri Oct 03, 2014 10:49 pm

The simplest antenna to understand is the simple dipole. Usually two 1/4 wave antennas. One for the positive connection (connected to the center of the coax). The other for the negative (connected to the shield of the coax). Each is 1/4 wave long so for 10m that would be about 2.5m per side or 5m total length.

Ideally this antenna would hang in free space away from any objects, but in practice just keep it as far from metal as possible. Attach some coax to the middle (or use a UHF connector for the center) and run the coax at away from the antenna at a right angle so it looks like a big "T". This antenna has a theoretical impedance of about 50 ohms so it can attach directly to the coax with no problems or gimmicks. Usually you cut the wires a little long then trim them down after installation till you get the best performance.

The next basic antenna to understand is the full wave loop. With this one you have 10m of wire (full wave) with one end connected to the center of the coax/connector, the other connects to the shield (negative). This has a theoretical impedance of about 200 ohms and will require some way to transform the impedance down to 50 ohm to match the coax and the radio. This is usually done with a 4:1 balun or an antenna tuner.
It also can be attached to the wall of your apartment.

Most antennas are variations on one of these two basic ideas.

ETA;
Also you should get some good amateur radio type coax like RG8, RG8x, 9913, LMR400, BF400, etc. Most amateur 50 ohm type of coax has enough copper/tin in the shield to allow soldering. Plus it's 50 ohm so it's a correct match for the radio. It's not expensive if you only need a few feet, so get the good stuff and keep it short.

Although consumer/cableTV type coax (RG6, RG11, CATV hardline, etc) is actually quite good, especially at higher frequencies, it usually is made with aluminum and will not solder to connectors. They are crimp only type. Plus 75 ohm is not quite right, but it will work in a pinch with crimp connectors and adapters.
"Victory awaits him who has everything in order, luck people call it. Defeat is certain for him who has neglected to take the necessary precautions in time; this is called bad luck"- The South Pole, Roald Amundsen - 1912

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