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Author Topic: Compact indoor antenna?  (Read 7301 times)
JOCONN
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Posts: 11




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« on: November 06, 2012, 03:51:42 PM »

Just moved to a new location. Don`t want to drill holes in walls of my new home for outdoor feed lines plus, I do not have attachment points for wire antennas. I am looking for plans for a compact indoor antenna that doesn`t have to be fastened to walls. I operate strictly low power cw. Shack will be on second floor of two storey wood frame house. Any ideas anyone? All replys appreciated.
Joe, VE9OCR
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JOCONN
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« Reply #1 on: November 06, 2012, 03:57:26 PM »

Oh-oh ... wrong forum. Should be in Antennas. CW is involved, though. Smiley
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VE3WMB
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Posts: 286




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« Reply #2 on: November 06, 2012, 07:00:11 PM »

Joe :

You don't mention what bands you want to operate.  I recently built a portable magnetic loop
out of 10 feet of 3/8 inch copper tubing and I have had good success working DX on 10m through
15m in recent weeks using CW @ 5W.  If you can find a decent quality butterfly or split stator capacitor
the remaining parts can be purchased at Home Depot.  My loop is very similar to K1RSTs at :

http://www.kr1st.com/magloop.htm

Michael VE3WMB

P.S. Efficiency of a well constructed loop of this size can be close to 90% on 10m and dropping to
about half that on 20m.

Just moved to a new location. Don`t want to drill holes in walls of my new home for outdoor feed lines plus, I do not have attachment points for wire antennas. I am looking for plans for a compact indoor antenna that doesn`t have to be fastened to walls. I operate strictly low power cw. Shack will be on second floor of two storey wood frame house. Any ideas anyone? All replys appreciated.
Joe, VE9OCR
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K6LO
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Posts: 226




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« Reply #3 on: November 06, 2012, 07:21:11 PM »

Do you have attic access? 
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K3STX
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Posts: 961




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« Reply #4 on: November 06, 2012, 07:36:33 PM »

Check this out:

http://www.comportco.com/~w5alt/antennas/index.php?pg=3

paul
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WX7G
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Posts: 5922




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« Reply #5 on: November 07, 2012, 04:48:10 AM »

I have been experimenting with a MFJ-933 loop tuner and it works well. With 1/2" copper tubing the loop can have a radiation efficiency of around 50%. This loop tuner works with loops that are 1/7 to 1/4 wavelength in circumference. For 80-10 meters four loop are used to cover the, 80, 40-30, 20-15, and 15-10 meter bands. As an example the 40 meter band loop is 20 feet in circumference. The loops can be circular, square, or rectangular.

Another good antenna is the mini-buddipole. It covers 40-2 meters and at $225 is hard to beat.

« Last Edit: November 07, 2012, 05:22:17 AM by WX7G » Logged
K3STX
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Posts: 961




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« Reply #6 on: November 07, 2012, 05:58:04 AM »

You don't need to drill holes to get wired or coax into your house!! Here is one idea, many of us made this as kids. It is a "feed-through" panel, basically put it at the BASE of your window and then close the window on top of it.

http://www.mfjenterprises.com/Product.php?productid=MFJ-4601

You DO have one attachment point, your second story window. You could put-up and end fed-Zepp with one end anchored at your window and another end to a fiberglass fishing pole (or some other mast) 40 feet away. I got my fiberglass collapsable crappie pole, a 16 footer for $20. Just don't use the top section of the crappie pole and "guy" it with thin rope.

OR put a small multiband vertical outside your house and use the feed-through panel to get the coax in.

When I set up my station in my new house, I simply hooked a 26 Ga. long wire to the "random wire" point on my MFJ tuner, ran the wire from the tuner to the window, closed the window onto the wire, and then threw the wire onto the roof of my house (maybe 60 feet total of wire). I attached 33 foot and 16 foot counterpoises to the tuner (1/4 wavelength on 40 and 20 meters). Using 100 watts I had no TVI and made LOTS of contacts. I think you will have much better luck with wire OUTSIDE your house. If you have a chimney, why not route the insulated antenna wire out your window and up to the chimney (tie it there with string). I think a tuner will be your friend, a used MFJ VersaTuner sounds like something you will NEED with narrow bandwidth antennas.

paul
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JOCONN
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« Reply #7 on: November 07, 2012, 11:00:38 AM »

Thanks all for the great advice. To K6LO, I do have attic space but it is not full size. Would a small loop for 10m qrp be safe to use indoors?
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WX7G
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« Reply #8 on: November 07, 2012, 11:14:10 AM »

Quite safe.
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KB3FEI
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« Reply #9 on: November 07, 2012, 03:32:14 PM »

I used a bulkhead through the window for several years. When I wanted to change it I, also, did not want to drill holes through the exterior walls. Finally, I decided to drill access holes in the soffit the size of barrel connectors, inserted the connectors and attached coax to either side of the barrels, then fed the line into the shack. I was able to secure the exterior coax (3 lines) to the gutter downspout with cable ties. Not perfect, but seems to work in my situation. Dale, kb3fei.
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GILGSN
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« Reply #10 on: November 08, 2012, 09:29:13 AM »

You might want to look into a magnetic loop...
That said, I have used a Buddistick inside, and it worked...

Gil.
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JOCONN
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« Reply #11 on: November 08, 2012, 09:57:42 AM »

Yes, I am seriously considering a mag loop for 10 and 20m. Also, the soffits, rain gutters and facia on my house are metal. Could I run a single wire from my tuner to this metal and use it as a random wire antenna? I could run the wire through the existing hole where the fibre op service comes in.
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GILGSN
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« Reply #12 on: November 08, 2012, 10:03:18 AM »

Certainly worth a try... See: http://www.hamuniverse.com/randomwireantennalengths.html

Gil.
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WX7G
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« Reply #13 on: November 08, 2012, 11:07:00 AM »

An inexpensive manual antenna tuner such as the MFJ-901B opens up a world of experimentation.
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PA0BLAH
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Posts: 0




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« Reply #14 on: November 08, 2012, 11:14:16 AM »

He asks for the rain gutter, I understand? That is according to me not so good idea. Metal joints often give harmonics and intermodulation due to rectifying effects. It will be not isolated, and when the metal is not copper but zinc or iron, the losses are high.

But with a tuner you can get your power in it; adjustment dependent on the weather.
73 Bob
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