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Beginner ham antenna questions
- Thread starter bhayles
- Start date
Which trees?
Wandering around deciding which trees will have the honor of supporting my first homemade antenna I find myself with a couple of questions, one of which I think I know the answer to but am not sure:
1. I'm in extreme north Georgia and I want my best RF radiation to cover as much of the US as possible and as much of Europe as possible. That means I choose my poor man's towers (trees) along a north/south line as much as possible, right?
2. How much deviation from a straight line can those three trees be in? If I did the antenna like this...:
KL3JM MODIFIED "SRI" MULTIBAND FAN DIPOLE - 80-40-20 METERS
...I could get both sides of the antenna lined up perfectly straight, but using three trees with one being a center support it will be hard to achieve a straight line. How much "bend" in the middle is OK?
Thanks,
Bob
Wandering around deciding which trees will have the honor of supporting my first homemade antenna I find myself with a couple of questions, one of which I think I know the answer to but am not sure:
1. I'm in extreme north Georgia and I want my best RF radiation to cover as much of the US as possible and as much of Europe as possible. That means I choose my poor man's towers (trees) along a north/south line as much as possible, right?
2. How much deviation from a straight line can those three trees be in? If I did the antenna like this...:
KL3JM MODIFIED "SRI" MULTIBAND FAN DIPOLE - 80-40-20 METERS
...I could get both sides of the antenna lined up perfectly straight, but using three trees with one being a center support it will be hard to achieve a straight line. How much "bend" in the middle is OK?
Thanks,
Bob
Me likey the loop:
Delta Loop Skywire Antenna 80m - 10m
Multiband, gain, and stupid simple to make. If you've got the space, it really is an antenna to consider.
73,
Brett
Delta Loop Skywire Antenna 80m - 10m
Multiband, gain, and stupid simple to make. If you've got the space, it really is an antenna to consider.
73,
Brett
Put it up, tune it, get on the air and see for yourself, in your specific location, with your specific equipment and power level, just HOW it's going to work. And go from there. If you want to make changes, just make ONE change at a time. (If you change two things before retesting and there is a big difference, you won't know which one actually is responsible.
BJ radionut
Supporting Member and 6m addict
Bob: As fan dipoles go, I like this design of construction. The trap (coil) inserted on 80/75m band will reduce performance "slightly" on that band.
That being said if this aids your ability to raise the antenna higher and makes the overall mounting of the antenna easier to manage for your install, then I think it's a non-issue.
Ok now to your question. You do not need to have the antenna perfectly straight really in either direction. That's to say it does not need to be perfectly "Flat".
Take the inverted "V" dipole... From the center (feedpoint) support to the end supports try and keep the angle of drop 30 degrees or less.
That's pretty well considered the optimum angle where the wires are 120 degrees. Now that does not mean it can not be less, the minimum is 90 degrees. This 90 degree line will effect the tuning somewhat, but if practical stay with an angle of 180(flat) to 120 degrees end to end. IMO this hold true in the other plane also. I wish I could do this with a CAD drawing for you to better see what I mean.
I think my explanation may sound confusing...in either "plane" you want the widest angle possible, any angle getting near 90 degrees will cause issues.
Bob also don't get to "Hung-Up" on your directions, unless this antenna is going to be 60 ft or more at the ends above ground, the radiation pattern will be distorted. Now this is not to say that is bad news, you look at some of the models and see this nice "figure 8" pattern off the broadside of the elements. You won't have it. You would see extra lobes appearing, possibly near the ends or middle of the elements. Your more likely to see something that could look like a "saw blade" where you'll have peaks and valleys in your pattern. I am getting to far here.
Bob get the antenna in the most practical spot for mounting, and get it up as high as possible. Keep those angles as wide and "GO FOR IT"
Then some where down the road you feel your not covering the world the way you like...Then move it around a little or put up a second dipole for one band or the other. This is work in progress old buddy:drool:
All the Best
Gary
That being said if this aids your ability to raise the antenna higher and makes the overall mounting of the antenna easier to manage for your install, then I think it's a non-issue.
Ok now to your question. You do not need to have the antenna perfectly straight really in either direction. That's to say it does not need to be perfectly "Flat".
Take the inverted "V" dipole... From the center (feedpoint) support to the end supports try and keep the angle of drop 30 degrees or less.
That's pretty well considered the optimum angle where the wires are 120 degrees. Now that does not mean it can not be less, the minimum is 90 degrees. This 90 degree line will effect the tuning somewhat, but if practical stay with an angle of 180(flat) to 120 degrees end to end. IMO this hold true in the other plane also. I wish I could do this with a CAD drawing for you to better see what I mean.
I think my explanation may sound confusing...in either "plane" you want the widest angle possible, any angle getting near 90 degrees will cause issues.
Bob also don't get to "Hung-Up" on your directions, unless this antenna is going to be 60 ft or more at the ends above ground, the radiation pattern will be distorted. Now this is not to say that is bad news, you look at some of the models and see this nice "figure 8" pattern off the broadside of the elements. You won't have it. You would see extra lobes appearing, possibly near the ends or middle of the elements. Your more likely to see something that could look like a "saw blade" where you'll have peaks and valleys in your pattern. I am getting to far here.
Bob get the antenna in the most practical spot for mounting, and get it up as high as possible. Keep those angles as wide and "GO FOR IT"
Then some where down the road you feel your not covering the world the way you like...Then move it around a little or put up a second dipole for one band or the other. This is work in progress old buddy:drool:
All the Best
Gary
Dipole Antenna Radiation Patterns by WB4YJT
Long read but well worth it.
I was of the thought process that higher is better when it comes to antennas.
This is true per say especially on the low bands 80 meters and 160 meters.
80 meters being 130' on a half W/L and 160 meters being 260' half W/L.
those heights are usually beyond the average amateurs antenna installation options.
With that said basically ony antenna below a half W/L in height acts as an omni directional radiation pattern.
Take this in consideration when installing your fan dipole.
IF you can get the apex of the fan dipole up 60' then 40 meters and up will come into consideration for an figure 8 radiation pattern.
In N georgia you would want to install your legs or elements of the antenna in a N/S direction and your radiation pattern will be E/W.
As said before install the antenna and see how it works. you can tell just by listening in on the bands which direction the antenna receives in, this is the direction it will also transmit your major lobes in.
As you build and experiment you will learn how to make your antenna do what you want it to do. A simple dipole installed correctly is a good antenna, cheap easy to construct and a lot of fun building. Best of all you can control the direction of the radiation pattern.
Long read but well worth it.
I was of the thought process that higher is better when it comes to antennas.
This is true per say especially on the low bands 80 meters and 160 meters.
80 meters being 130' on a half W/L and 160 meters being 260' half W/L.
those heights are usually beyond the average amateurs antenna installation options.
With that said basically ony antenna below a half W/L in height acts as an omni directional radiation pattern.
Take this in consideration when installing your fan dipole.
IF you can get the apex of the fan dipole up 60' then 40 meters and up will come into consideration for an figure 8 radiation pattern.
In N georgia you would want to install your legs or elements of the antenna in a N/S direction and your radiation pattern will be E/W.
As said before install the antenna and see how it works. you can tell just by listening in on the bands which direction the antenna receives in, this is the direction it will also transmit your major lobes in.
As you build and experiment you will learn how to make your antenna do what you want it to do. A simple dipole installed correctly is a good antenna, cheap easy to construct and a lot of fun building. Best of all you can control the direction of the radiation pattern.
10, 20, and 40m wire pairs cut and 80m will have to wait. Dark-thirty caught me before I could finish.
I still haven't shown up on the database and that disappoints me a bit. I have these dual band Baofengs and I wanna TALK! before heading to the hospital early tomorrow morning...
I'll be missing in action for a few days...I gotta have some plumbing reworked inside my head tomorrow and will be in the hospital for a few days, but will get back to work on the antenna as soon as I get home.
The good thing is my radio and assorted goodies WH0AI included along with the rig should be here waiting for me when I get home (hopefully Saturday afternoon). That and the antenna should give me plenty to play with for a while!
Thanks for all the help, guys, and as Arnold says..."I'll be bach!" (Poor Austrian imitation)
73's,
Bob
I still haven't shown up on the database and that disappoints me a bit. I have these dual band Baofengs and I wanna TALK! before heading to the hospital early tomorrow morning...
I'll be missing in action for a few days...I gotta have some plumbing reworked inside my head tomorrow and will be in the hospital for a few days, but will get back to work on the antenna as soon as I get home.
The good thing is my radio and assorted goodies WH0AI included along with the rig should be here waiting for me when I get home (hopefully Saturday afternoon). That and the antenna should give me plenty to play with for a while!
Thanks for all the help, guys, and as Arnold says..."I'll be bach!" (Poor Austrian imitation)
73's,
Bob
Home from the hospital. I've got a few days of recouperation then its back to thye antenna so I can use this radio that was waiting for me when I got home a while ago. Now THAT is what needs to be waiting for folks when they come home from the hospital...a new (to them) radio.
Incidentally, I must mention...its AMAZING what a good surgeon can do inside your head from an incision in your groin. I have one carotid artery that is 100% occluded and cannot be cleared and the other was getting there. My doc cleaned out the artery using the same technique (sorta) that he used to clean out and stent a few of my coronary arteries over the last few years. Cool!
Incidentally, I must mention...its AMAZING what a good surgeon can do inside your head from an incision in your groin. I have one carotid artery that is 100% occluded and cannot be cleared and the other was getting there. My doc cleaned out the artery using the same technique (sorta) that he used to clean out and stent a few of my coronary arteries over the last few years. Cool!
BJ radionut
Supporting Member and 6m addict
Bob: Go for it...if the tuning is less than 2 to1..load it up
Did you get your call already?
All the Best
gary
PS: Glad all went well last couple days...that should make you feel better
Did you get your call already?
All the Best
gary
PS: Glad all went well last couple days...that should make you feel better
BJ radionut
Supporting Member and 6m addict
Kenwood TS 130S...seller threw in a mic (wasn't supposed to be included in the deal), a 1:1 balun, ~100ft of rg58, two pl239 connectors w/reducers for the rg58, and an MFJ 30 amp power supply.
Call sign STILL hasn't come through yet...probably Monday I guess.
BJ radionut
Supporting Member and 6m addict
Hang in there Bob it happen...but hook up to the 99 and listen around...It will help you get use to the rig...
I still own a TS-130SE ( SE= Special Edition) one of the last ones made...has all the WARC bands already installed (30m/17m/12m) not all the 130's came installed with them...the band switch had them on front but they would not transmit(some not receive either) because it was not legal to use those bands when some were made...
Have fun
All the Best
Gary
I still own a TS-130SE ( SE= Special Edition) one of the last ones made...has all the WARC bands already installed (30m/17m/12m) not all the 130's came installed with them...the band switch had them on front but they would not transmit(some not receive either) because it was not legal to use those bands when some were made...
Have fun
All the Best
Gary
Last edited:
BJ radionut
Supporting Member and 6m addict
http://www.worldwidedx.com/general-ham-radio-discussion/168894-newbie-2.html
They get you your call much faster now
They get you your call much faster now
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