I'd like to try building a loaded Yagi. I came across plans for a 20 meter
mini Yagi while Googling, but I want something for 15 meters. Are there any
simple, free calculators available? Also, can anyone tell me a ballpark
figure how a 15 meter shortened (by 40%) 3 element Yagi would compare to a
full sized one? How about if I added an additional element for 4 loaded
elements instead of 3?

Thanks,
harry

In message , Harry Brown
writes
I'd like to try building a loaded Yagi. I came across plans for a 20
meter mini Yagi while Googling, but I want something for 15 meters.
Are there any simple, free calculators available? Also, can anyone
tell me a ballpark figure how a 15 meter shortened (by 40%) 3 element
Yagi would compare to a full sized one? How about if I added an
additional element for 4 loaded elements instead of 3?

Thanks,
harry

MMANA has a 3 element loaded yagi as an example.

Http://hamsoft.ca/pages/mmana-gal.php and it's free

Short Yagi W1FBY & WA1LNQ

It's got a gain of about 4.7dB

I dare say 4NEC2 will model it as well.

Brian GM4DIJ
--
Brian Howie

"Brian Howie" wrote in message
...

MMANA has a 3 element loaded yagi as an example.

Thanks. I downloded this "MMANA-GAL basic" but couldn't find the example
loaded Yagi anywhere in any of the antenna menus. Can you tell me what the
file is called and/or should I have tried out the "pro" version? Thanks,
harry


Http://hamsoft.ca/pages/mmana-gal.php and it's free

Short Yagi W1FBY & WA1LNQ

It's got a gain of about 4.7dB

I dare say 4NEC2 will model it as well.

Brian GM4DIJ
--
Brian Howie

In message , Harry Brown
writes

"Brian Howie" wrote in message
...

MMANA has a 3 element loaded yagi as an example.

Thanks. I downloded this "MMANA-GAL basic" but couldn't find the
example loaded Yagi anywhere in any of the antenna menus. Can you tell
me what the file is called and/or should I have tried out the "pro"
version? Thanks, harry



Yes it's the basic one, the file is in

\MMANA-GAL_Basic\ANT\HF short

and the file is called

"3el short Yagj W1FBY.maa"

Brian


--
Brian Howie

"Brian Howie" wrote in message
newsbNQuPH3DcHPFwfT@b-

Yes it's the basic one, the file is in

\MMANA-GAL_Basic\ANT\HF short

and the file is called

"3el short Yagj W1FBY.maa"

Brian

Interesting. I don't seem to have either that folder nor file. I'm using
version 3.0.0.25.

Harry

In message , Harry Brown
writes

"Brian Howie" wrote in message
newsbNQuPH3DcHPFwfT@b-

Yes it's the basic one, the file is in

\MMANA-GAL_Basic\ANT\HF short

and the file is called

"3el short Yagj W1FBY.maa"

Brian

Interesting. I don't seem to have either that folder nor file. I'm
using version 3.0.0.25.

Harry

Same here. I'll e-mail it .

Brian

--
Brian Howie

On Fri, 20 Jan 2012 15:07:37 -0500, "Harry Brown"
wrote:

I'd like to try building a loaded Yagi.
I came across plans for a 20 meter
mini Yagi while Googling, but I want something for 15 meters. Are there any
simple, free calculators available?

Modeling programs I like and use:
http://www.yagicad.com
http://home.ict.nl/~arivoors/
http://www.eznec.com (the demo version should work).

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com
# http://www.LearnByDestroying.com AE6KS

ARRL Antenna Book has all the answers.

Shortening the antenna will reduce the effective radiated power and will reduce the amount of gathering ability of the antenna.
Every time you reduce the size by 25% - you throw away - probably 50% of it's ability.

Antenna's are always a compromise when you get into the lower ranges.
It is easier to BUY a Mosley tribander - about $1000.00, then to try to make your own.

As the elements are shortened or lengthened, all of the variables has to be recalculated because the spacing will also change and the boom length.

http://fermi.la.asu.edu/w9cf/yagipub/index.html

http://www.ac6v.com/antsoftware.htm

On Jan 22, 9:02*pm, Channel Jumper Channel.Jumper.
wrote:
ARRL Antenna Book has all the answers.

Shortening the antenna will reduce the effective radiated power and will
reduce the amount of gathering ability of the antenna.

Uhh.. not really. for small scale shortening, the directivity will
remain roughly the same. Losses are fairly small, in general, so you
don't get a big change between loaded and unloaded (unless you pick a
particularly lossy way to load it)

What WILL change is that the dimensional tolerances and bandwidth will
be narrower. That is, you won't get the same gain over as wide a
band.

You will also not get as good F/B or side/back lobe performance in
general.


Every time you reduce the size by 25% - you throw away - probably 50% of
it's ability.

I don't think so. Can you demonstrate this with a simple model?

The physical size of a Yagi isn't all that closely related to the
effective aperture, at least for 10-20% sorts of size changes. Sure,
go to half or quarter size and losses will start to increase because
of the increased stored energy.



Antenna's are always a compromise when you get into the lower ranges.
It is easier to BUY a Mosley tribander - about $1000.00, then to try to
make your own.

As the elements are shortened or lengthened, all of the variables has to
be recalculated because the spacing will also change and the boom
length.

Yes, but today, you've got a LOT of help from very good and validated
modeling codes. No more are you looking at tedious cut and try.

The real thing that's going to affect performance for a small antenna
is mechanical details.. how are elements attached, what kind of
dimensional tolerances can you hold, how big is the tubing, stuff like
that.