On Sat, 3 Apr 2004 11:25:34 -0600 (CST),
(Richard Harrison) wrote:
Kraus says on page 229 of his 1950 edition:
"Whereas the characteristic impedance of a biconical antenna is uniform,
the impedance of antennas of shapes other than conical is nonuniform."

Hi Richard,

This analysis is derived from Schelkunoff's work that was later (1952)
offered in his "Advanced Antenna Theory." This material is offered in
a more accessible form in "Antennas and Radiowave Propagation," Robert
E. Collin, 1985 with the following observation:
"In his book Schelkunoff shows .... the biconical antenna theory
provides a theoretical basis for assuming a sinusoidal current
distribution on thin-wire antennas."

Basically, the biconical antenna theory is the basis for the
fundamental treatment of antenna as a non-terminated transmission line
by which all thin-wire antennas may be shown to devolve from (as the
degenerate forms of infinitely small radius cone sections). Such
treatment allows those interested to observe both the SWR relationship
(E/I distribution) of thin-wire elements compared to what you
correctly identify as the uniform impedance of the large cone angle
forms and both be mathematically consistent with such diverging
characteristics (which is to say those who oppose the discussion of
Antenna as transmission line are unaware of this work).

However, as to its application in a Yagi-Uda design, it has to be
particularly unrewarding as nearby elements preclude a full-blown
conic development without the attending physical interference.

73's
Richard Clark, KB7QHC

Richard Clark wrote:
"This analysis is derived from Schelkunoff`s work that was later (1952)
offered in his "Advanced Antenna Theory"."

Kraus acknowledges this at the beginning of his 1950 "Antennas" chapter
8:
"This problem (input resistance and reactance) is most simply approached
by Schelkunoff`s treatment of the biconical antenna (S.A. Schelkunoff,
"Electromagnetic Waves"1943) which will be outlined in the following
sections."

As Reg Edwards says, these guys all copied each other`s work. But, they
nearly always gave each other the credit due.

Other than a few discones, which have 180-degrees as one of their vertex
angles, I don`t see many amateur conical antennas despite the obsession
with bandwidth and SWR. Skeletal designs might retain desirable
characteristics without extreme cost and complexity.....Nah, the plain
thin wire dipole is too simple and easy.

Best regards, Richard Harrison, KB5WZI

I contacted LB about the problem

This page details the information that is available about the URL
http://www.cebik.com/gup/gup21-5.gif that is available in the WWWOFFLE cache.

Header
The cached header contained the following items (this is before
WWWOFFLE has modified it and possibly censored some items).

HTTP/1.0 403 Forbidden
Connection: close
Date: Thu, 01 Apr 2004 23:01:29 GMT
Server: Apache/1.3.26 (Unix) FrontPage/5.0.2.2510 PHP/4.3.4
Content-Type: text/html; charset=iso-8859-1

Sure hope there are no assumptions made about how we are fetching his pages.

"Dave Platt" wrote in message
...
In article ,
Roy Lewallen wrote:

Quite a few years ago, there were a couple of articles -- in Ham Radio
magazine, I believe --, which addressed that topic. As I recall, the
author used an optimization program that allowed the shape to vary. He
ended up with elements bent kind of like a gull wing, and considerably
longer than a half wavelength -- more like a wavelength if I recall
correctly. The gain was substantially more than for a Yagi, but I don't
remember how good the F/B ratio was. I believe he did construct and
measure some actual antennas.

I think you're referring to the Landstorfer-Sacher Yagi design?

http://www.cebik.com/eb.html has some information on these. It's
something akin to an EDZ (extended double zepp) beam. A 2-meter
3-element L-S Yagi shows gain in the 9.7 dB range, with F/B ratios of
16-23.

Interesting design. Not the easiest thing in the world to construct,
I suspect.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

I believe this antenna pretty much lost out to stacked arrays. It proved to
be too much for a nickel and not enough for a dime.

LB has gotten his web page fixed, so I can see the graphics now. Figure
10 on the URL referenced below is indeed the antenna I was referring to.

Roy Lewallen, W7EL

Dave Platt wrote:

In article ,
Roy Lewallen wrote:


Quite a few years ago, there were a couple of articles -- in Ham Radio
magazine, I believe --, which addressed that topic. As I recall, the
author used an optimization program that allowed the shape to vary. He
ended up with elements bent kind of like a gull wing, and considerably
longer than a half wavelength -- more like a wavelength if I recall
correctly. The gain was substantially more than for a Yagi, but I don't
remember how good the F/B ratio was. I believe he did construct and
measure some actual antennas.


I think you're referring to the Landstorfer-Sacher Yagi design?

http://www.cebik.com/eb.html has some information on these. It's
something akin to an EDZ (extended double zepp) beam. A 2-meter
3-element L-S Yagi shows gain in the 9.7 dB range, with F/B ratios of
16-23.

Interesting design. Not the easiest thing in the world to construct,
I suspect.