Velocity Factor of Coax
 

Hello all
What determines the Velocity Factor of a coax cable.
Is it the center conductor awg,dielectric,shield or all combined
I am building a
Lindenblad Antenna for 2 Meters

its asked to use

RG-59 polyethylene foam coax with stranded center conductor

I think the VF is .66

I cant find any stranded center cond where I am,so I want to try it with
Solid,but it seems all the solid is VF .88

anyone have any input on this

thanx

howard

Velocity Factor of Coax
 

sorry I should mention the RG-59 is used for impedance matching not feed
line
thanks again
Howard

"Howard Kowall" wrote in message
...
Hello all
What determines the Velocity Factor of a coax cable.
Is it the center conductor awg,dielectric,shield or all combined
I am building a
Lindenblad Antenna for 2 Meters

its asked to use

RG-59 polyethylene foam coax with stranded center conductor

I think the VF is .66

I cant find any stranded center cond where I am,so I want to try it with
Solid,but it seems all the solid is VF .88

anyone have any input on this

thanx

howard

Velocity Factor of Coax
 

"Howard Kowall" wrote in message
...
sorry I should mention the RG-59 is used for impedance matching not feed
line
thanks again
Howard

"Howard Kowall" wrote in message
...
Hello all
What determines the Velocity Factor of a coax cable.
Is it the center conductor awg,dielectric,shield or all combined
I am building a
Lindenblad Antenna for 2 Meters

its asked to use

RG-59 polyethylene foam coax with stranded center conductor

I think the VF is .66

I cant find any stranded center cond where I am,so I want to try it with
Solid,but it seems all the solid is VF .88

anyone have any input on this

thanx

howard


It's principally the relative permittivity of the dielectric that determines
the velocity factor. Air alone would yield a value of unity but the
presence of a spacer of some sort means practical values are smaller. Foam
can get close to air.

I wonder why you need a Lindenblad for 2 metres - do you really need good
circular polarisation over a range of elevation angles (and omni HRP, of
course)?

Chris

Velocity Factor of Coax
 

On Feb 9, 3:26*pm, "Howard Kowall" wrote:
What determines the *Velocity Factor of a coax cable.
Is it the center conductor awg,dielectric,shield or all combined
I am building a Lindenblad Antenna for 2 Meters.

The velocity of propagation (v.p.) in each branch of the feed harness
won't affect the relative field radiation pattern of such an antenna
array as long as the same electrical lengths of coax are used between
the power divider outputs and the feedpoint of each element of the
array.

The v.p. of the main transmission line from the tx to the input of of
the antenna power divider in this scenario is irrelevant.

RF

Velocity Factor of Coax
 

"Howard Kowall" wrote in message
...
Hello all
What determines the Velocity Factor of a coax cable.
Is it the center conductor awg,dielectric,shield or all combined
I am building a
Lindenblad Antenna for 2 Meters

its asked to use

RG-59 polyethylene foam coax with stranded center conductor

I think the VF is .66

I cant find any stranded center cond where I am,so I want to try it with
Solid,but it seems all the solid is VF .88

anyone have any input on this

thanx

howard

Hi Howard

I am interested in reception of CP signals from all points within the
upper hemisphere. I am curious about your purpose for this Lindenblad.

Jerry KD6JDJ

Velocity Factor of Coax
 

"Jerry" wrote in message
...

"Howard Kowall" wrote in message
...
Hello all
What determines the Velocity Factor of a coax cable.
Is it the center conductor awg,dielectric,shield or all combined
I am building a
Lindenblad Antenna for 2 Meters

its asked to use

RG-59 polyethylene foam coax with stranded center conductor

I think the VF is .66

I cant find any stranded center cond where I am,so I want to try it with
Solid,but it seems all the solid is VF .88

anyone have any input on this

thanx

howard

Hi Howard

I am interested in reception of CP signals from all points within the
upper hemisphere. I am curious about your purpose for this Lindenblad.

Jerry KD6JDJ


Ever tried crossed 'wilted' dipoles?

Chris

Velocity Factor of Coax
 

On Mon, 9 Feb 2009 15:30:50 -0600, "Howard Kowall"
wrote:

sorry I should mention the RG-59 is used for impedance matching not feed
line
thanks again
Howard

"Howard Kowall" wrote in message
...
Hello all
What determines the Velocity Factor of a coax cable.
Is it the center conductor awg,dielectric,shield or all combined
I am building a
Lindenblad Antenna for 2 Meters

its asked to use

RG-59 polyethylene foam coax with stranded center conductor

I think the VF is .66

I cant find any stranded center cond where I am,so I want to try it with
Solid,but it seems all the solid is VF .88

You might want to consider using RG-6/u instead of RG-59. These daze,
the quality of RG-59 coax is rather marginal. I've seen 80% coverage
shielding and cable unsuitable for outdoor use. Meanwhile, the CATV
people have switched to RG-6/u for everything. Much of it is quad
shielded and UV resistant. Velocity factor is usually 0.66 for solid
dielectric and anywhere between 0.7 and 0.9 for various foam
dielectric mixes. When you find a suitable piece of cable, grab the
manufacturer and full part number. Then, lookup the VF on the mfg
data sheet.


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

Velocity Factor of Coax
 

hello all
thanks all who read and emailed back
lot of good info came in and I have a good handle on it
I am building this antenna for rhcp portable satellite antenna for LEO Ham
Radio Sat
thanks again
Howard

"Howard Kowall" wrote in message
...
Hello all
What determines the Velocity Factor of a coax cable.
Is it the center conductor awg,dielectric,shield or all combined
I am building a
Lindenblad Antenna for 2 Meters

its asked to use

RG-59 polyethylene foam coax with stranded center conductor

I think the VF is .66

I cant find any stranded center cond where I am,so I want to try it with
Solid,but it seems all the solid is VF .88

anyone have any input on this

thanx

howard

Velocity Factor of Coax
 

I've found quite a variation in foamed dielectric cable velocity factor
from lot to lot of the same brand and type, even with major brands.
Apparently they don't control the density of the dielectric very well.
So if you're planning on using foamed dielectric cable in an application
where VF is important, I highly recommend that you measure the VF of a
sample from the same piece you'll be using.

Roy Lewallen, W7EL

Velocity Factor of Coax
 

"Howard Kowall" wrote in message
...
hello all
thanks all who read and emailed back
lot of good info came in and I have a good handle on it
I am building this antenna for rhcp portable satellite antenna for LEO
Ham Radio Sat
thanks again
Howard

"Howard Kowall" wrote in message
...
Hello all
What determines the Velocity Factor of a coax cable.
Is it the center conductor awg,dielectric,shield or all combined
I am building a
Lindenblad Antenna for 2 Meters

its asked to use

RG-59 polyethylene foam coax with stranded center conductor

I think the VF is .66

I cant find any stranded center cond where I am,so I want to try it with
Solid,but it seems all the solid is VF .88

anyone have any input on this

thanx

howard

Hi Howard

The Lindenblad has an overhead null that you might find anoying for some
high elevation passes of LEOs.
Are you open to trying to build a DCA (which is an antenna that I
developed)? I make the claim that there is no other hemispheric coverage
antenna design that performs better than a DCA. But, I sure am open to
being corrected.
The Feb 2008 QST contains an article on the DCA antenna design concept.
It is my claim that a DCA is extreemely forgiving of construction errors
and uses 4 wire dipoles and 50 ohm coax with 5 RFI type ferrites as
"baluns'.

Jerry KD6JDJ