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Author Topic: I want to make my own antenna.  (Read 641 times)
KJ4CMA
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Posts: 21




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« on: March 16, 2008, 12:56:07 PM »

But... I have a few restrictions.

I live in an apartment.  It really sucks, but this is a temporary arrangement anyway.  However, this means several restrictions, including the fact that all construction has to be done inside (no copper cacti - Don't like the idea of soldering inside with a torch) and everything has to fit inside.  My shack is in the "junk room" so to speak, so it really doesn't matter what it looks like.  Oh yeah... this is for 2 meters as well.

I've come across a billion antenna designs, but many are either designed for outdoor use, require some form of torch soldering, have plans that look like cave drawings, etc.  

Anyone have any recommendations for a first time antenna builder without a lot of room to work with?
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WB2WIK
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Posts: 20636




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« Reply #1 on: March 16, 2008, 01:10:36 PM »

Indoor antennas for 2m don't ever work well, but it's all a matter of accepting the compromise.

If you want to build an inexpensive antenna that works as well as *anything* in an apartment possibly can, build a vertical dipole made of ordinary hookup wire (gauge not important, #18 or #20 is great, #22 should be okay): Each "leg" of the dipole needs to be 19" long, so the overall length end-to-end is 38".  Use a center insulator made of anything non-conductive.  Solder a piece of RG58/U or similar to the two elements as per normal dipole construction.

Now, lay the wire dipole against an outside glass window, orienting it vertically.  Use a piece of adhesive tape to "tack" the top and the bottom of the dipole, then use more tape to route the coax horizontally away from the center of the dipole to the window frame.  Make that horizontal piece of coax at least 19" long (longer is better) before you tape or tack it in position to hold its routing and let it drop down towards the floor or wherever it needs to go.

Then use more, stronger tape to more permanently attach the vertical wire dipole to the window.  If you use transparent tape (recommended!), when you're done, from the "outside" this really won't look like anything -- just a wire taped to a window, certainly not any sort of antenna.

It will work better than a $500 antenna located "inside" the apartment, and will cost maybe $50-$10 to build, including a short run of coax (RG58 is typically $0.25/foot).

Reason is, it's half outside, where it needs to be.

WB2WIK/6

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WB2WIK
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Posts: 20636




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« Reply #2 on: March 16, 2008, 01:11:54 PM »

Sorry, typo in that last!

I meant to type, "$5 to $10 to build..."
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KJ4CMA
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Posts: 21




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« Reply #3 on: March 16, 2008, 04:59:48 PM »

Well, that took me all of 10 minutes to build!

Works pretty good, too.  Got to use it a bit on the QSO party and the net, without too many complaints.  Used the full 50 watts for the QSO contest as well.  

Thanks!
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KB9BVN
Member

Posts: 116




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« Reply #4 on: March 18, 2008, 10:10:20 AM »

You used 50w on 2m with an indoor antenna?

Smell anything burning?

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WB8YYY
Member

Posts: 159


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« Reply #5 on: March 18, 2008, 02:26:41 PM »

Sounds like you are enjoying a good vertical antenna!  If you decide later you want more gain on 2m, a 2 element cubical quad can be made with PVC or you might consider a homemade yagi.  I made a 2 meter beam from a FM radio antenna, but i had someone's precise recipe for the conversion.  Note for FM vertical polarization is the norm - essential otherwise your beam will not have much gain over the vertical!  As sunspots increase, and you get interested in HF, you may be able to construct something useful -- but for HF very likely you will need to explore portable operating and/or use of a club station.  Don't rule out participating as an operator in field day - a club or other multiperson team will get you plugged in.  
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KJ4CMA
Member

Posts: 21




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« Reply #6 on: March 18, 2008, 05:12:18 PM »

Nope, no burning.  I ran it at 50 watts for a cumulative 10 seconds or so.  Normally won't use it as i can hit the local repeater with 5 anyway.  

HF is in the plans, but fortunately for me I'll likely be out of here before long anyways and into a free standing house where I can have all the boat projects and antennas  I can handle.  If HF comes to reality before then, I'm sure I can get creative, anyway.  I have a "balcony" meaning a sliding glass door that opens directly to a railing.  I'm not afraid to hang something outside for a few hours during the evening, just no permanent installs.
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KE4DRN
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Posts: 3734




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« Reply #7 on: March 19, 2008, 06:43:10 PM »

hi,

take a look at the half square for 2 meters,
you can hang it in near the window and nobody
will see it if you have the shade down.

http://www.cebik.com/hs.html

you can build this one fast and for a few dollars.
Nice performance and direct fed with coax.

This one is little harder to build but also is a great performer almost as good as the yagi.

http://www.cebik.com/moxbld.html

I use both of them with good results.
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2E0BSS
Member

Posts: 85




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« Reply #8 on: March 28, 2008, 03:19:47 PM »

How about a loop antenna ? they're light and small but very effective.

2E0BSS
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