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Beginner ham antenna questions

Thanks guys...and a question, of course!

I'm going to do an antenna like this, except with a 1:1 balun added, just for good measure:

MULTI BAND HF FAN DIPOLE ANTENNA DESIGN

I do have a question about radial length(s). I'm doint the same 4 bands...10, 20, 40, and 80 meters. I am guessing the radial length(s) in this antenna design are based on the absolute middle of each band. Is that where I want to be? I'm guessing that as I get out towards the edges the radiowaves quality drops a little. If one end of the band is better than the other, should I use a different frequency for figuring the radial lengths? Or...am I over thinking the whole thing and I should just go with the lengths given in the linked article?...:confused1:

Thanks guys!

EDIT: I just re-read that and my question is clear as mud. Let's try again:

Say Band A is frequencies 1-10. The length of the radial would total 468/5, or 93...correct? But what if frequencies 8, 9, and 10 were rarely used, and 1, 2, and 3 were heavily used? Wouldn't I get better performance for the portion of the band that is actually used by using either 468/4 or even 468/3? I'd lose the higher frequencies that are rarely used, but wouldn't the quality of the reception on the portion that IS used be better?

If I'm right, what frequency should I use for each of the 10, 20, 40, and 80 meter bands?
 
Last edited:
bhayles said:
I'm going to do an antenna like this, except with a 1:1 balun added, just for good measure:

MULTI BAND HF FAN DIPOLE ANTENNA DESIGN

I do have a question about radial length(s). I'm doint the same 4 bands...10, 20, 40, and 80 meters. I am guessing the radial length(s) in this antenna design are based on the absolute middle of each band. Is that where I want to be? I'm guessing that as I get out towards the edges the radiowaves quality drops a little. If one end of the band is better than the other, should I use a different frequency for figuring the radial lengths? Or...am I over thinking the whole thing and I should just go with the lengths given in the linked article?...:confused1:

Thanks guys!

EDIT: I just re-read that and my question is clear as mud. Let's try again:

Say Band A is frequencies 1-10. The length of the radial would total 468/5, or 93...correct? But what if frequencies 8, 9, and 10 were rarely used, and 1, 2, and 3 were heavily used? Wouldn't I get better performance for the portion of the band that is actually used by using either 468/4 or even 468/3? I'd lose the higher frequencies that are rarely used, but wouldn't the quality of the reception on the portion that IS used be better?

If I'm right, what frequency should I use for each of the 10, 20, 40, and 80 meter bands?
Click to expand...

BH: Again Congrats and Keep going!

Here's a couple of Terms you'll find most Hams using.
Now this is not a slam by any means. Your doing Fab OM
In the context your asking substitute the word;

Radial for Element: When speaking in regards to a DIpole...a dipole has 2 elements or (2) radiating elements for each band.

A Radial is a term MOST commonly used as a component of a Vertically polarized antenna...A Vertical Ground Plane Antenna...
Again this can start a whole thread by itself, but I think most here will agree these terms are most Generally used in this form.

Don't get to lost on these tuning points W9CLL is correct. Even with the best calculations your going to have to make adjustments to lengths of the elements
The 468/Freq in Mhz in most cases will be Long...This will mean that the Frequency you calculated your elements for will not truly be where the antenna is actually resonant. Most generally it will be below or lower in frequency. Don't fret this, as every location and antenna situation can be different.
Now not to confuse your question.
Here's some good frequencies to try your element calculations
10m-28.400
20m-14.275
40m-7.100
80m-3.900

These again are just my suggestions, but over time I've found these good points to shoot for when building dipoles for the General Class Phone bands

Dinner Call!:tt1:
All the Best
Gary
 
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BH: Now as to your question in regards to Preformance.
This is where alot of op's get hung up. A vswr of 2.0 to 1, if my old memory still serves me is 98% efficient. So putting this in simple terms, if you have 100 watts of power delivered to the feed point of the dipole(the insulator)at a 2.0 to 1 VSWR the antenna will radiate 98 watts. Now in most cases radios of the modern Ara will accept this and not reduce the output. Some of the early solid state HF rigs like the TS120/130/140 and the same vintage ICOM radios will in some cases reduce the output to protect the final transistors from overheating or seeing a mismatch greater than 2 to 1..
So keeping this in mind any VSWR of 1.5 to 1 can be considered to be 100% efficient.
So to put this in the context of your question, if you have a dipole on 80m which is 2 to 1 VSWR at 3.8 Mhz....1.5 to1 at 3.9 Mhz ....2 to 1 at 4.0 Mhz...
We have a Winner! NO one and I mean NO one will ever see a difference in signal strength if your antenna is 98% or 100%...if they say they can Balderdash:D!
HB, this is just an example again every antenna install can and will differ. This is just a shooting range.
I've seen antenna installs do exactly this and sometimes better bandwith, however most generally somewhat less. It is all determined by multiple factors, examples of which are the height above ground, objects in near-by proximity and the size or diameter of the radiating elements. Again just to name a few!:D
Damn it's getting windy around here:whistle:
All the Best
Gary
 
BJ radionut said:
BH: Again Congrats and Keep going!....
Now not to confuse your question.
Here's some good frequencies to try your element calculations
10m-28.400
20m-14.275
40m-7.100
80m-3.900

These again are just my suggestions, but over time I've found these good points to shoot for when building dipoles for the General Class Phone bands

Dinner Call!:tt1:
All the Best
Gary
Click to expand...

is that a typo?
7.100 might be a "little" low in the general fone band:unsure:
 
Road Squawker said:
is that a typo?
7.100 might be a "little" low in the general fone band:unsure:
Click to expand...

I take a shot at explaining the 7.100.

The dipole will still cover the upper phone portion of 40 meters with a decent VSWR that will make the rig happy.

AND it will allow the use of the 15 meter band the third harmonic 21.300 mhz of the 40 meter band thus why the target freq is 7.100 mhz.

Just my guess.
 
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