help with macthing system on delta loop
 

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 , delta 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,

The impedance of a Full Wave Delta Loop antenna is theoretically in the
vicinity of 100 ohms. That is why I use a 75 ohm "Q section" to provide a
perfect match to the 50 ohm coax. My Loop antenna is flat 1:1 VSWR around
3.875 Mhz and rises to about 2:1 SWR at 3.75 and 4 Mhz . So I cover the
entire 75 meter band without using a tuner.


Here is How I Do It.


IMPORTANT - Connect the shield of a "Short Piece" of 75 ohm coax to one end
of the loop antenna , Connect the center of the 75 ohm coax to the other end
of the loop antenna. The length of the 75 ohm coax is most important. It
will be used as a Q section.
To determine the length to use, Use this formula "Length in feet = 246 x VF
/ Freq in Mhz" VF = the Velocity Factor of the coax. So multiply 246 by the
Velocity Factor of the coax , Then divide by the frequency .


If you use RG59 or RG11 with a Velocity Factor of 0.66 , For the 75 meter
band the Piece of 75 ohm coax should be about 42 feet long , It doesn't need
to be exact . RG59 and RG11 coax usually have a Velocity Factor of 0.66 ,
Foam dielectric coax such as RG6 might have a Velocity Factor of 0.81 or
more.


Put a PL259 coax connector on the unused end of the 75 ohm coax, Screw a
PL258 double female coax connector onto this PL259 coax connector. Then
connect 50 ohm coax to the other side of the PL258 double female coax
connector, Use any length 50 ohm coax needed to reach your Transceiver.

Ace - www.WH2T.com



"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 , delta 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 , delta 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 .............



I think Ace has you taken care of.
Matching sections are magic. I've used them to match dissimilar transmission
cables as well as antennas.
the quarter-wave 75-ohm section is especially useful for loops.



---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.788 / Virus Database: 533 - Release Date: 11/1/2004