I would like to express my appreciation for all those who have taken the
time to respond to my post. Being new to antenna design and construction
I understand some of my questions and comments may seem a bit "silly"
and it would be easy for people to suggest that I go learn more first or
simply use trial and error.

I have a practical requirement for a flexible whip antenna that results
in "good" gain that works but at the same time I want to learn what I
can because it is my intention to later experiment with other style of
antenna (Yagi at 434MHz is next on my list).

Now, back to the 1/4 wave, phasing coil, 1/2 wave design.

Does this means for a practical antenna I could have...

SMA plug centre pin - 1/4 length of wire - several turns of wire
around the Radome - 1/2 length of wire ? (ie. coax earth braid stops at
SMA and rest of antenna is made up of inner conductor and dielectric only).

Is it that "simple" ? If so, that would be easy to construct in a
flexible whip (which is my aim) compared to many of the other suggestions.

Is the gain the same as a dipole ?

Also, I have EZNEC 4. but have not had a chance to learn it yet. Can you
model the coil in the program or can you only enter segments ?

Thanks.

Steve Nosko wrote:
"Cecil Moore" wrote in message
...

...
But I've given you all the information in Kraus' book
about that particular antenna. Laid on its side:

| + - +
|----------/////--------------------
| 1/4WL coil 1/2WL

The coil is a 180 deg. phase reversing coil. [snip]
73, Cecil,


Yep and this makes it a "phasing" coil and the antenna a colinear. The
phasing coil causes the current in the two sections of the antenna to be in
phase. Note my addition of polarity indicators to the above diagram. The
right end of both elements are the same = in phase currents. Now you have a
half wave and a quarter wave in phase, yielding gain by a flatter pattern
(whicn is vertical in this drawing).
You can stack half waves up like this and this is done in common cellular
gain antennas - probably WiMax as well. There are several ways to do the
phasing... Coils like this, quarter-wave shorted stubs (parallel-line),
reverse connecting alternate sections of coaxial t-line as elements, phasing
harnesses on the feed line... Probably more.

73, Steve, K;9'D.C,I