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11 Meter Loop Antenna

ZuMBLe

Member
Oct 15, 2010
68
1
16
I live in a 1st floor apt of a 3 story building. I recently got back in to radios and have been getting on when I can from my parent's place, but that's not enough. =) How well do you all think this will get out?
11 Meter Loop Antenna

I was thinking of mounting this around my window. The plans call for a piece of RG59 to match with the RG58, can I just skip that step and use RG58 and an antenna tuner? Would it be better to use the RG59/RG58 and then use a tuner? Is this antenna a waste of time? =)
 
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W5LZ

Crotchety Old Bastard
Apr 8, 2005
6,832
823
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Oklahoma
First, that RG-59 coax is being used as an impedance matching device. If you don't us it, your SWR with just a straight run of RG-58, or any other 50 ohm coax, will be fairly high, probably around a 2:1 or worse. A full wave loop antenna is not a 50 ohm antenna at all, it's typically around 100 - 150 ohms. You really do need that RG-59.
Windows come in all sizes so that loop may certainly 'fit' around yours. Just keep in mind that if the loop is made in a square, it'll be about 9 feet on each side. I don't have two windows together that would fill that sort of space.
- 'Doc
 
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Robb

Yup
Dec 18, 2008
11,433
3,566
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Silicon Valley CA, Storm Lake IA
Quoted from the link you gave:

" . . . Make sure the bare wire used for the loop is hanging in free air and insulted from everything except the string it is hanging on . . . "

Needs to be parallel to the ground and suspended away from objects - especially. Otherwise, nearby objects will subject it to capacitance and then cause it to become detuned from the target frequency/band.

Not saying it won't work. I'm saying that you must stick to the design principles that will allow it to work for you as you would expect. Go for it . . .
 

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ZuMBLe

Member
Oct 15, 2010
68
1
16
Crap, I forgot the window frames are metal, that's going to be a problem. Not sure I want to mount it on my ceiling. I'm definitely going to try this though. Will use the RG59. I'm sure I can pick up some from radio shack since I need to pick up the antenna wire also.

Do I absolutely need bare wire?
 

HomerBB

Supporting Member
Jan 4, 2009
3,861
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Rogers, Ar
I've made and used this loop antenna. Should you find it necessary to suspend it from the ceiling I suggest you make it a square shape running it flat on the same plane as the ceiling is, and feed it on one of the corners. Allow the feed line to drop straight down to the radio with no horizontal runs. I understand this should give you a vertical polarity which would be handy for talking locally, too.

In anticipation of any and all corrections to what I've just written I say in advance, "I stand corrected". ;)

Before I did without an antenna I'd do it in a heartbeat.

Good Luck
 

wavrider

W9WDX Amateur Radio Club Member
Jun 2, 2009
3,404
1,268
173
Stick a mag mount on your refrigerator if you need an inside antenna.
 

ZuMBLe

Member
Oct 15, 2010
68
1
16
Not sure how well that will work because the fridge is literally located in the middle of the building. At least if I run the loop in my bedroom, I'm near a window and at the front of the building. The mag mount wouldn't be more than 3 feet high if mounted on top of the fridge. =(

Stick a mag mount on your refrigerator if you need an inside antenna.
 

HomerBB

Supporting Member
Jan 4, 2009
3,861
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Rogers, Ar
Can you put a flag pole mount outside your window? If you can I suggest this bracket (available at The Home Depot for less than $11):


6fe1466c-f5a5-4dcb-9344-b4c262bde81e_300.jpg


Put an aluminum pole in this plastic flag pole holder on you wall as high up as you are permitted to put it and trail a wire down the wall from it. The center coax conductor goes to the aluminum pole (start with a pole and wire length of around 9' each), and the coax shield goes to the wire hanging down against the wall. You are making a dipole. Tune it to lowest SWR by shortening the pole and wire by equal amounts until you've gotten the SWR where you need it.
 

ZuMBLe

Member
Oct 15, 2010
68
1
16
Unfortunately, no. I may just ask my landlord if I could put something up on the roof, but 10/11 meter verticals are pretty scary looking to non-radio people.

I figured I'd try making one of these loops before stirring up trouble. ;) Now I remember why I became a ham, I could work the world with a HT. Too bad I don't find using repeaters as fun as HF.



Can you put a flag pole mount outside your window? If you can I suggest this bracket (available at The Home Depot for less than $11):


6fe1466c-f5a5-4dcb-9344-b4c262bde81e_300.jpg


Put an aluminum pole in this plastic flag pole holder on you wall as high up as you are permitted to put it and trail a wire down the wall from it. The center coax conductor goes to the aluminum pole (start with a pole and wire length of around 9' each), and the coax shield goes to the wire hanging down against the wall. You are making a dipole. Tune it to lowest SWR by shortening the pole and wire by equal amounts until you've gotten the SWR where you need it.
 

MisterFatty

Poppin Fresh!
Aug 1, 2008
698
34
38
Here is something else to consider, especially for your chosen frequency. I'm currently Using two mag loops to cover 10-80 meters, efficiency drops at lower frequencies but still quite usable.

Besides stealth, noise level is greatly reduced, drawbacks are fairly narrow banded, and the need for High voltage caps if you go beyond QRP.

Still worth a look.

Homemade Magnetic Loop antenna for 27 MHz
 

ZuMBLe

Member
Oct 15, 2010
68
1
16
Wow! That's super interesting but may be beyond what I'm capable of. I'm going to look in to it though. Thanks!

Here is something else to consider, especially for your chosen frequency. I'm currently Using two mag loops to cover 10-80 meters, efficiency drops at lower frequencies but still quite usable.

Besides stealth, noise level is greatly reduced, drawbacks are fairly narrow banded, and the need for High voltage caps if you go beyond QRP.

Still worth a look.

Homemade Magnetic Loop antenna for 27 MHz
 

dudmuck

Active Member
May 21, 2007
482
11
28
tustin, ca
Wow! That's super interesting but may be beyond what I'm capable of. I'm going to look in to it though. Thanks!

Agreed.
This magnetic loop most surely can be a great antenna if you have the construction skills and the materials available. Cannot stress how narrow-band this antenna is. Its a great asset for noise reduction, but it really does need a good motor to retune when you change frequencies. Copper quality of the big loop is so important. The ready-made version of this antenna is more than $400, but its constructed to eliminate arcing problems. Very high voltage on the capacitor, bad connections will arc. You dont want an indoor antenna if you have concern about exposing your body to strong RF fields. You might consider staying mobile for radio operations if thats the case.
 

CDX-007

Transducer Fanatic
Jan 26, 2006
706
17
28
I live in a 1st floor apt of a 3 story building. I recently got back in to radios and have been getting on when I can from my parent's place, but that's not enough. =) How well do you all think this will get out?
11 Meter Loop Antenna

I was thinking of mounting this around my window. The plans call for a piece of RG59 to match with the RG58, can I just skip that step and use RG58 and an antenna tuner? Would it be better to use the RG59/RG58 and then use a tuner? Is this antenna a waste of time? =)

What's the chance you could move to the 3rd floor?!

I helped a friend build a plastic palm tree antenna for his 4th story deck with a 1/4 wave wire inside it and two on the wood deck for counterpoise and that little 11' high home-brew antenna talked all over...




...everyone's TVs, stereos, telephones, etc... :whistle:
 

ZuMBLe

Member
Oct 15, 2010
68
1
16
The chance of my moving to the 3rd floor is zero, I like my first floor apt. =)

I have a low pass filter which I'll be using to hopefully eliminate interference. :p

What's the chance you could move to the 3rd floor?!

I helped a friend build a plastic palm tree antenna for his 4th story deck with a 1/4 wave wire inside it and two on the wood deck for counterpoise and that little 11' high home-brew antenna talked all over...




...everyone's TVs, stereos, telephones, etc... :whistle:
 

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