Dumb question about EZNEC
 

Hi- was searching Amazon , and see several books on Strip Line Antennas
my biggie is: Eznec will take WIRE DIA, and Dial. Constant, and
Thickness in inches of that dialectric. Does this mean that EZNEC is
useable to substrate material (G-10, Teflon, ect) to model Printed
Circuit antennas?
IF so, how do you go from a WIRE Diameter, to a Rectangular wire,
(say 3 MM X width of 5 MM,by x cm long), on a plane of G-10 ?
Or is this beyond its capabilities? Just curious if can handle this!
Maybe am halucinateing, again!

Comments, please! Jim NN7K

Dumb question about EZNEC
 

Jim-NN7K wrote:
Hi- was searching Amazon , and see several books on Strip Line Antennas
my biggie is: Eznec will take WIRE DIA, and Dial. Constant, and
Thickness in inches of that dialectric. Does this mean that EZNEC is
useable to substrate material (G-10, Teflon, ect) to model Printed
Circuit antennas?

No.

. . .

Roy Lewallen, W7EL

Dumb question about EZNEC
 

Jim-NN7K wrote:
Hi- was searching Amazon , and see several books on Strip Line Antennas
my biggie is: Eznec will take WIRE DIA, and Dial. Constant, and
Thickness in inches of that dialectric. Does this mean that EZNEC is
useable to substrate material (G-10, Teflon, ect) to model Printed
Circuit antennas?
IF so, how do you go from a WIRE Diameter, to a Rectangular wire,
(say 3 MM X width of 5 MM,by x cm long), on a plane of G-10 ?
Or is this beyond its capabilities? Just curious if can handle this!
Maybe am halucinateing, again!

Comments, please! Jim NN7K

Imagine attempting to model these masks of DLM antennas:

http://assemblywizard.fr33webhost.com/masklayout.pdf

;-)

Regards,
JS

Dumb question about EZNEC
 

Thanks- just was curious- while still working had sites with wedge
shaped antennas- one broke its ray-dome - these (Scala?) were on
960MHz , and the antenna itself appeared to be a Log-Periodic ,
on a double sided Printed Circuit board- Just curious as to the effects
on impedence, and element lengths-spacing , as to how this antenna
was designed. Jim NN7K



Roy Lewallen wrote:
Jim-NN7K wrote:
Hi- was searching Amazon , and see several books on Strip Line Antennas
my biggie is: Eznec will take WIRE DIA, and Dial. Constant, and
Thickness in inches of that dialectric. Does this mean that EZNEC is
useable to substrate material (G-10, Teflon, ect) to model Printed
Circuit antennas?

No.

. . .

Roy Lewallen, W7EL

Dumb question about EZNEC
 

"John Smith" wrote in message
...
Jim-NN7K wrote:
Hi- was searching Amazon , and see several books on Strip Line Antennas
my biggie is: Eznec will take WIRE DIA, and Dial. Constant, and
Thickness in inches of that dialectric. Does this mean that EZNEC is
useable to substrate material (G-10, Teflon, ect) to model Printed
Circuit antennas?
IF so, how do you go from a WIRE Diameter, to a Rectangular wire,
(say 3 MM X width of 5 MM,by x cm long), on a plane of G-10 ?
Or is this beyond its capabilities? Just curious if can handle this!
Maybe am halucinateing, again!

Comments, please! Jim NN7K

Imagine attempting to model these masks of DLM antennas:

http://assemblywizard.fr33webhost.com/masklayout.pdf

;-)

Regards,
JS

So how would they be fed? Monopole needs a GP or fed as doublet. I have
anxiety just looking at it.

Inverted L is soo much easier.

Dumb question about EZNEC
 

JB wrote:
"John Smith" wrote in message
...
Jim-NN7K wrote:
Hi- was searching Amazon , and see several books on Strip Line Antennas
my biggie is: Eznec will take WIRE DIA, and Dial. Constant, and
Thickness in inches of that dialectric. Does this mean that EZNEC is
useable to substrate material (G-10, Teflon, ect) to model Printed
Circuit antennas?
IF so, how do you go from a WIRE Diameter, to a Rectangular wire,
(say 3 MM X width of 5 MM,by x cm long), on a plane of G-10 ?
Or is this beyond its capabilities? Just curious if can handle this!
Maybe am halucinateing, again!

Comments, please! Jim NN7K
Imagine attempting to model these masks of DLM antennas:

http://assemblywizard.fr33webhost.com/masklayout.pdf

;-)

Regards,
JS

So how would they be fed? Monopole needs a GP or fed as doublet. I have
anxiety just looking at it.

Inverted L is soo much easier.



They would be fed though a series capacitance to a tap on the lower
coil, at a point to obtain a 50 ohm feed point, generally ... and
considering the 1/2 wave design.

A 1/4 wave design would simply be fed at the base of the lower coil with
a sufficient ground plane provided ...

.... in the monopole models.

A T or Delta match could/would be implemented on a dipole version.

Regards,
JS

Dumb question about EZNEC
 

On Tue, 26 Aug 2008 10:05:19 -0700, Jim-NN7K .
wrote:

Thanks- just was curious- while still working had sites with wedge
shaped antennas- one broke its ray-dome - these (Scala?) were on
960MHz , and the antenna itself appeared to be a Log-Periodic ,
on a double sided Printed Circuit board- Just curious as to the effects
on impedence, and element lengths-spacing , as to how this antenna
was designed. Jim NN7K

Would a photo help? This is the guts of a Sinclair SRL441-2P:
http://11junk.com/jeffl/antennas/Sinclair%20SRL441-2P/index.html

Data sheet at:
http://www.sinclairtechnologies.com/catalog/product.aspx?id=962

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

Dumb question about EZNEC
 

Jeff Liebermann wrote:
On Tue, 26 Aug 2008 10:05:19 -0700, Jim-NN7K .
wrote:

Thanks- just was curious- while still working had sites with wedge
shaped antennas- one broke its ray-dome - these (Scala?) were on
960MHz , and the antenna itself appeared to be a Log-Periodic ,
on a double sided Printed Circuit board- Just curious as to the effects
on impedence, and element lengths-spacing , as to how this antenna
was designed. Jim NN7K

Would a photo help? This is the guts of a Sinclair SRL441-2P:
http://11junk.com/jeffl/antennas/Sinclair%20SRL441-2P/index.html

Data sheet at:
http://www.sinclairtechnologies.com/catalog/product.aspx?id=962

Yep, Thats the Beast! These used by railroad, for double track
installations, for boxcar readers (Automatic Equipment Identification)
and mounted at ground level, aimed up about 30 degree angle,to read
ID tags.
Thanks, Jim NN7K

Dumb question about EZNEC
 

On Wed, 27 Aug 2008 08:26:23 -0700, Jim-NN7K .
wrote:

Jeff Liebermann wrote:
On Tue, 26 Aug 2008 10:05:19 -0700, Jim-NN7K .
wrote:

Thanks- just was curious- while still working had sites with wedge
shaped antennas- one broke its ray-dome - these (Scala?) were on
960MHz , and the antenna itself appeared to be a Log-Periodic ,
on a double sided Printed Circuit board- Just curious as to the effects
on impedence, and element lengths-spacing , as to how this antenna
was designed. Jim NN7K

Would a photo help? This is the guts of a Sinclair SRL441-2P:
http://11junk.com/jeffl/antennas/Sinclair%20SRL441-2P/index.html

Data sheet at:
http://www.sinclairtechnologies.com/catalog/product.aspx?id=962

Yep, Thats the Beast! These used by railroad, for double track
installations, for boxcar readers (Automatic Equipment Identification)
and mounted at ground level, aimed up about 30 degree angle,to read
ID tags.
Thanks, Jim NN7K

We'll, there's not much that I can tell you about the design. It's a
log-periodic antenna built onto a PCB. It's not G10/FR4 and might be
Polysulfone. Like the LPDA acronym suggests, it's nothing but a mess
of dipoles at varying frequencies, which results in lots of bandwidth
and not much gain.

This might help with the numbers:
http://www.changpuak.ch/electronics/lpda.html
Use Frequency 800-1000MHz and 180mm boom length.
It's not exactly the same as the Sinclair LPDA uses staggered
elements.

Other calculators:
http://www.fortunecity.com/skyscraper/jolt/345/LogCalc.html
LPDA Excel Spreadsheet calcs:
http://www.astro.hr/ucionica/radioastronomy/antenna/lpda.zip
Another LPDA calculator (that I haven't tried):
http://www.astro.hr/ucionica/radioastronomy/antenna/lpcad23.zip

More light reading:
http://www.wolfgang-rolke.de/antennas/ant_400.htm
http://en.wikipedia.org/wiki/Log-periodic_antenna

A $40 commerical LPDA for 400-1000GHz.
http://www.ramseyelectronics.com/cgi-bin/commerce.exe?preadd=action&key=LPY41

If you want to see the effects of juggling spacing, element count, and
boom length, it's probably best to use an antenna modeling program.
Looks like you have EZNEC, which will work. If you download the 4NEC2
antenna modeling program, you'll also get a mess of example NEC2
files. There's a directory under:
c:\4nec2\models\logper\
with 4 log periodic antennas, mostly for HF. EZNEC can read them. I
can probably conjur my bad guess of a model of the Sinclair antenna,
but I'm playing vacation and would rather be doing something else.



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

Dumb question about EZNEC
 

I routinely use EZNEC to design antennas printed on a substrate. I do
the basic design then apply a fudge factor to the conductor width and
length derived from comparisons between model results and measurements
of real antennas. Final designs usually take some adjustment even at
that. However, I haven't tried this for any antenna that depends
strongly on coupling between elements, such as a Yagi, because the
mutual coupling will also be affected by the substrate and won't be so
easy to approximate. In the case of a log periodic, I'd adjust the model
transmission line to try and get the same Z0 and velocity factor as the
line on the substrate, which you might have to determine by measurement.
That would help, but you'd still be lacking accurate mutual coupling
information. At best, I think, a model would get you in the ballpark,
with a final design requiring some tweaking.

Roy Lewallen, W7EL