One-Radial Ground Plane vs Dipole

[hotrod]

Funny y'all should mention the Sirio Balcony 27. I have been looking at that one but can't find hardly any reviews. Apparently these are really popular in Europe.

Am a little confused. I thought it was a ground plane with 1 radial, not a dipole, since it can be mounted to metal. Can someone clear this up for me?

Thanks!

theres actually both . the balcony 27 is a 1/4wave antenna with 1 radial and only handles
450 watts .
the sirio dipole is a 1/2 wave and will handle 1000 watts.this is what all base antennas
are measured against. this also can be mounted verticle or horizonal. cbradiomagizine did a
review on it.go to dnjradio and click on cb&10m base antennas, he has several

 

[nosepc]

nosepc,

I have a dumb question. Are those transmission reflection patterns, or reception?

antenna model does not distinguish between transmision and reception

 

[Riverman]

Thanks, hotrod. Thanks, everybody.

My original intent was to build a dipole using Firestiks like the one on this page:

https://sites.google.com/site/2mt454/Home/11-meter-cb-antennas

then attach it vertically to my eave, let the rain gutter do to it whatever it's gonna do, and see what I've got. In addition to the gutter, the bottom of the antenna will only be 5' from the ground (equally bad), but my only alternative is a 15' mast (which will only add 5' as my eave is 10' from the ground.) But heck, if I'm gonna do that, I might should consider the Sirio SD-27 1/2 wave dipole you suggested. It will still be low to the ground, but with the gamma tuner, maybe it will perform better than my homebrew.

I guess I could mount either horizontally on the mast but then they'll be parallel to the rain gutter which I understand is even worse than having it perpendicular if mounted vertically.

Decisions, decisions. I'm too old for this

 

[Riverman]

antenna model does not distinguish between transmision and reception

Thanks, nosepc.

 

[W5LZ]

Any antenna that close to metal (a foot or so) will be affected by it. No way of telling how it would be affected, but it will be. It doesn't have to be a bad effect though, or maybe not -much- of an affect.
One alternative to that 'nearness' would be to use that rain gutter as part of the antenna's 'other half', or the 'groundplane'/counterpoise. It would definitely change the antenna's tuning and radiation pattern, no idea how though. Who knows, it might be beneficial.
One thing about making an antenna using two shortened elements like mobile antennas is that it will definitely not be easy to tune, they get real 'picky', you know? You also shouldn't expect much 'broadbandedness'.
If your aim is to talk to 'locals' then a vertical antenna of some sort is a good choice. Polarity, horizontal/vertical has a big affect, a common polarity is desirable in most cases. If most people around you use a vertical antenna then you will find a vertical will 'talk' to more people than a horizontal antenna will. The opposite is also true, if they got a horizontal antenna then you'd want one.
There's more to it than that, but that should at least get you talking.
Have fun.
- 'Doc

 

[Riverman]

Thanks, 'Doc.

I'm learning (and remembering) more and more.

 

[hotrod]

Thanks, hotrod. Thanks, everybody.

My original intent was to build a dipole using Firestiks like the one on this page:

https://sites.google.com/site/2mt454/Home/11-meter-cb-antennas

then attach it vertically to my eave, let the rain gutter do to it whatever it's gonna do, and see what I've got. In addition to the gutter, the bottom of the antenna will only be 5' from the ground (equally bad), but my only alternative is a 15' mast (which will only add 5' as my eave is 10' from the ground.) But heck, if I'm gonna do that, I might should consider the Sirio SD-27 1/2 wave dipole you suggested. It will still be low to the ground, but with the gamma tuner, maybe it will perform better than my homebrew.

I guess I could mount either horizontally on the mast but then they'll be parallel to the rain gutter which I understand is even worse than having it perpendicular if mounted vertically.

Decisions, decisions. I'm too old for this

your idea would probaly work. but your tx/rx wouldnt be very good. probaly be about the
sameas you would if ya just mounted that antenna on a car. as it was design for.
exactly what are your plans for talking. locally or dx ,both? the sirio sd-27 on that 15
feet of pipe will do ok for ya obviously higher would even be better but should work
ok at 15 feet thats close to 1/2 wavelenth above ground

 

[Riverman]

I would like to talk a little of each (local/dx).
Am still considering the SD-27.

And thanks for your comments on my other thread "Wilson 1000 Base Station Antenna".

Between this thread and that one, I should be able to come up with something that suits me.

 

[Riverman]

I fizzled out on this idea and purchased a ProComm Patriot PAT-12 instead.

Here's the thread: http://www.worldwidedx.com/cb-antennas/77866-procomm-patriot-12-foot-cb-base-antenna-advise-4.html

 

[Skynet 15]

I know this subject is years old, I'm very new to these forums but I am currently doing this same setup for county use in a small club of mine for the time being.
I have 5' mobile antenna at 5/8 wave, my understanding is I need 3 radials at 8' and a rf choke . So this is what I've done. Now my main question it is mounted to a series of aluminised steel poles to bring it roughly 40' high. Should i ground the pole out? Separate the antenna and radials from the metal poles by PVC? Any input would help so much thanks in advance.

 

[Needle Bender]

I know this subject is years old, I'm very new to these forums but I am currently doing this same setup for county use in a small club of mine for the time being.
I have 5' mobile antenna at 5/8 wave, my understanding is I need 3 radials at 8' and a rf chokeView attachment 17415 View attachment 17416 . So this is what I've done. Now my main question it is mounted to a series of aluminised steel poles to bring it roughly 40' high. Should i ground the pole out? Separate the antenna and radials from the metal poles by PVC? Any input would help so much thanks in advance.

Attach 3-4 guy wires at the tip of the mast/grounded base of the antenna mount, but at 9' down the guy wires place an insulator - now you've got the 1/4 wave bottom half of the half wave of current you need to get out well.

The RF doesn't much care if it's isolated from the mast but it could help to prevent RF Interference getting down into your radio/TV, computer speakers, etc. to isolate it by adding a couple feet of solid 1" fiberglass rod to insulate/isolate the whole affair,
then wrap 5 1/2 turns of the coax in a 4" diameter choke hanging around the fiberglass and above the top of the mast to attain the most isolation possible, but Personally, I wouldn't worry about it unless RFI was a problem.
Get this on 40' of mast and you should get out really well. But why not make it a full 102" whip, you'll get gain over that smaller antenna, especially on receive.

 

[Skynet 15]

Attach 3-4 guy wires at the tip of the mast/grounded base of the antenna mount, but at 9' down the guy wires place an insulator - now you've got the 1/4 wave bottom half of the half wave of current you need to get out well.

The RF doesn't much care if it's isolated from the mast but it could help to prevent RF Interference getting down into your radio/TV, computer speakers, etc. to isolate it by adding a couple feet of solid 1" fiberglass rod to insulate/isolate the whole affair,
then wrap 5 1/2 turns of the coax in a 4" diameter choke hanging around the fiberglass and above the top of the mast to attain the most isolation possible, but Personally, I wouldn't worry about it unless RFI was a problem.
Get this on 40' of mast and you should get out really well. But why not make it a full 102" whip, you'll get gain over that smaller antenna, especially on receive.

Hey thanks for the reply and information it was a real help, yes I do have RFI, and if I'm understanding correct I should isolate the firestik from the pole itself. Plus change my choke to a 4" tube instead of a 2" with 5 1/2 turns instead of my 8. Also my guy lines are a nylon rope so it was my understanding I didnt have to worry to much about insulators on the 3 radials. Furthermore, would you suggest 4 at 9' or the 3 at 8' I have now? Thanks for the help in advance.

 

[Skynet 15]

Also, any thoughts on the 102" whip or a more expensive 18' 4 pc base antenna?

 

[The DB]

With a 102" whip (plus ground plane radials), get it to the same tip height as a 18' antenna and they will perform the same. If you notice a difference between them then one of them has a problem.

The only reason longer antennas outperform shorter antennas is they have a higher tip height, and by extension a higher current node (located 1/4 wavelength down from the tip). This current node height, along with the quality of the earth below, are what determines things like the gain and radiation angle, aka radiation pattern.

A longer antenna mounted at the same mounting height has an advantage over a shorter antenna only because the antennas additional length puts the tip and current node higher. Adding additional mast to a shorter antenna will have the same effect. Further, this advantage becomes less of an advantage the higher the compared antennas are mounted above the earth. Get the antennas mounted at 30' to 40' height over the earth and you won't even notice the difference...


The DB

 

[Skynet 15]

With a 102" whip (plus ground plane radials), get it to the same tip height as a 18' antenna and they will perform the same. If you notice a difference between them then one of them has a problem.

The only reason longer antennas outperform shorter antennas is they have a higher tip height, and by extension a higher current node (located 1/4 wavelength down from the tip). This current node height, along with the quality of the earth below, are what determines things like the gain and radiation angle, aka radiation pattern.

A longer antenna mounted at the same mounting height has an advantage over a shorter antenna only because the antennas additional length puts the tip and current node higher. Adding additional mast to a shorter antenna will have the same effect. Further, this advantage becomes less of an advantage the higher the compared antennas are mounted above the earth. Get the antennas mounted at 30' to 40' height over the earth and you won't even notice the difference...


The DB

thanks for the input, it makes more sense now, so I'm on the rite track, it's just boiling down to my radial lengths and getting the rf choke to work better being I'm getting a bit of rfi. I still get out there pretty far and clean.