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LOOP ANTENNA
- Thread starter doctor
- Start date
A couple of years ago a guy on Copper's forum built himself a two element antenna, similar to a quad like the PDL-II, only it had circular elements instead of square or diamond shaped ones. I think he just fed it direct to the driven element with the coax.
I'm pretty sure it worked quite well for him, he may even still be on that forum, but who knows. That certain "tech" over there has driven a lot of good people away.
I'm pretty sure it worked quite well for him, he may even still be on that forum, but who knows. That certain "tech" over there has driven a lot of good people away.
you mentioned skip, so i suppose you are considering a horizontal loop since most skip talking is done horizontally polarized. If that is your goal, you can check out http://www.bloomington.in.us/~wh2t/loop.html
Then scale it down for 11 meters, if thats your only band of interest. I would think it would be a cost effective antenna if you have the support structures for it, such as trees.
A vertical loop is a completely different beast, and directional. Often used on the lower HF bands as a separate receive antenna, to null out man-made noise.
Then scale it down for 11 meters, if thats your only band of interest. I would think it would be a cost effective antenna if you have the support structures for it, such as trees.
A vertical loop is a completely different beast, and directional. Often used on the lower HF bands as a separate receive antenna, to null out man-made noise.
doctor,
Horizontal full wave loop antennas are not directional if they are fairly symmetrical in shape. An odd shaped one will have some directivity, not too predictable, mostly.
Vertical full wave loops are directional, just like the driven element of a 'quad'. The shape of the loop also determines the 'shape' of the radiation pattern to some extent, sort of.
How high should one be, horizontal or vertical? As high as you can get it! More higher is more better, just like almost all antennas.
The input impedance of a typical full wave loop is something on the order of 100 - 150 ohms. Using a 1/4 wave matching section of 75 ohm coax, then 50 ohms to the radio is one common way of matching that that. Don't expect a 1:1 SWR, but do look for it to be around 1.5:1 give or take a little.
Or, feed the thing with ladder line through a tuner and who cares what the input impedance is, won't matter.
Skip or local? Both. Maybe not consistently, but as consistent as using any other kind of antenna.
You can also pick the polarity you want, horizontal of vertical polarization, depending on the shape of the thing (just like a 'quad'). A square loop fed in the middle of one side yields a horizontal polarization. Feeding it at one corner yields a vertical polarization.
A full wave loop usually has about 2 dBd gain, sort of. That depends on a lot of things, height, environment, color if the wire used, etc. Another advantage is that a loop, being a 'closed circuit' antenna, is typically quieter than a dipole or vertical. Not a lot quieter, but some.
Really want an antenna that can be used almost anywhere/band? Huge loops are very nice. If it's more than one wave length, as in two, or three, there is more gain achieved. It gets sort of directional though and may not be in the direction you want (this is with a horizontal loop, by the way, but a vertical one does about the same thing).
I like loop antennas. They tend to do as well as most others, and better in some cases. Also like to feed them using ladder line and a tuner. Tends to work fine on any band higher than what it's made for. Are they the 'end-all' of antennas? 'Course not, but they sure are handy thingys to have.
- 'Doc
Horizontal full wave loop antennas are not directional if they are fairly symmetrical in shape. An odd shaped one will have some directivity, not too predictable, mostly.
Vertical full wave loops are directional, just like the driven element of a 'quad'. The shape of the loop also determines the 'shape' of the radiation pattern to some extent, sort of.
How high should one be, horizontal or vertical? As high as you can get it! More higher is more better, just like almost all antennas.
The input impedance of a typical full wave loop is something on the order of 100 - 150 ohms. Using a 1/4 wave matching section of 75 ohm coax, then 50 ohms to the radio is one common way of matching that that. Don't expect a 1:1 SWR, but do look for it to be around 1.5:1 give or take a little.
Or, feed the thing with ladder line through a tuner and who cares what the input impedance is, won't matter.
Skip or local? Both. Maybe not consistently, but as consistent as using any other kind of antenna.
You can also pick the polarity you want, horizontal of vertical polarization, depending on the shape of the thing (just like a 'quad'). A square loop fed in the middle of one side yields a horizontal polarization. Feeding it at one corner yields a vertical polarization.
A full wave loop usually has about 2 dBd gain, sort of. That depends on a lot of things, height, environment, color if the wire used, etc. Another advantage is that a loop, being a 'closed circuit' antenna, is typically quieter than a dipole or vertical. Not a lot quieter, but some.
Really want an antenna that can be used almost anywhere/band? Huge loops are very nice. If it's more than one wave length, as in two, or three, there is more gain achieved. It gets sort of directional though and may not be in the direction you want (this is with a horizontal loop, by the way, but a vertical one does about the same thing).
I like loop antennas. They tend to do as well as most others, and better in some cases. Also like to feed them using ladder line and a tuner. Tends to work fine on any band higher than what it's made for. Are they the 'end-all' of antennas? 'Course not, but they sure are handy thingys to have.
- 'Doc
Thanks for all the answers.
I have one up and it slopes from 30 feet and the ends to 12 feet to 15 feet, so I have noticed it is directional at this point north/south, becuase a friend who lives east about 45 miles is shall we say barely audible until I switch to my astroplane, I am thinking of a eleven meter loop/, but the one I use now is ten thru 40, to an antenna tuner, I would say it will suffice 1 to 1 swr..
Anyhow thanks again
doctor/795 :shock:
I have one up and it slopes from 30 feet and the ends to 12 feet to 15 feet, so I have noticed it is directional at this point north/south, becuase a friend who lives east about 45 miles is shall we say barely audible until I switch to my astroplane, I am thinking of a eleven meter loop/, but the one I use now is ten thru 40, to an antenna tuner, I would say it will suffice 1 to 1 swr..
Anyhow thanks again
doctor/795 :shock:
loop
I put one up yesterday, it slopes down so is somewhat directional, it is picking signals from north and south, and east/west negative, friend lives east and no signal at all on his transmissions, friends to the north loud/clear.
Now to get some pvc pipe mount the ends to it and move it around, if the weather holds, antenna experimentation is fun
DOCTOR/795 :shock:
I put one up yesterday, it slopes down so is somewhat directional, it is picking signals from north and south, and east/west negative, friend lives east and no signal at all on his transmissions, friends to the north loud/clear.
Now to get some pvc pipe mount the ends to it and move it around, if the weather holds, antenna experimentation is fun
DOCTOR/795 :shock:
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