please need help with delta loop antenna better matching system than gamma match
 

hi..........
please need help with delta loop antenna better matching system than gamma
match............. please could any body sugest any thing or way to match a
vee quad , dela loop other than gamma match and my be supply me with details
how to assemble and fit to antenna .........gee some must no a better way..
please help me 73s .......... thanks every one that may be able
to help .............

"Silvio" wrote in message
...
hi..........
please need help with delta loop antenna better matching system than gamma
match............. please could any body sugest any thing or way to match
a
vee quad , dela loop other than gamma match and my be supply me with
details
how to assemble and fit to antenna .........gee some must no a better
way..
please help me 73s .......... thanks every one that may be
able
to help .............



Hi, Silvio -

I am not very good at antennas and such, but I'll give it a shot.

EZNEC says a delta loop fed at the vertex (at the bottom) appears as about
122 Ohms at resonance. You could use a 1:1 balun and a quarter wave piece of
75 Ohm coax and then 50 Ohm coax for the remainder of the trip to your
transmitter. At the 75/50 Ohm point your impedance would appear as 46 Ohms.
This would give you an SWR of about 1.08:1.

If you do not have 75 Ohm coax, you could instead insert an open stub of
about .381 wavelengths at about .159 wavelengths below the balun using all
50 Ohm coax.

And then there is the possibility of using open wire line with a tuner.

Hopefully, I did all this correctly. If not, I hope someone else will jump
in here and correct me.

Good luck.

John

Sylvio,

I use full wave delta loops on 30 meters and 40 meters. To match them I use
a 1/4 wave 75 ohm feedline. (multiplied times the velocity factor of the
coax - about .81)

So, from the back of my radio I have a random length of RG/8 50 ohm coax.
Then I insert a 1/4 wave of 75 ohm coax to the antenna. This works quite
well for me and results in SWR of 1.1:1.

-larry
K8UT
"Silvio" wrote in message
...
hi..........
please need help with delta loop antenna better matching system than gamma
match............. please could any body sugest any thing or way to match
a
vee quad , dela loop other than gamma match and my be supply me with
details
how to assemble and fit to antenna .........gee some must no a better
way..
please help me 73s .......... thanks every one that may be
able
to help .............

"Silvio" wrote in message
...
hi..........
please need help with delta loop antenna better matching system than gamma
match............. please could any body sugest any thing or way to match
a
vee quad , dela loop other than gamma match and my be supply me with
details
how to assemble and fit to antenna .........gee some must no a better
way..
please help me 73s .......... thanks every one that may be
able
to help .............




In addition to the 75 Ohm line that people have mentioned, there are also
2:1 and 2.25:1 matching transformers. Amidon sells the 2:1, but it is
expensive, $59, as I recall. Personally, I use 1/4 wavelength of RG11, but a
transformer might be better for multiband use.

Tam/WB2TT