On Sat, 03 Feb 2007 18:29:41 -0600, Bob Bob
wrote:

- I know of the issues with radiating feedline and pattern lifting for
the jpole. Wondering if a 4:1 coaxial balun would resolve this and also
give a wider VSWR bandwidth?

Hi Bob²,

Nope. The width is determined by Q. Pattern is determined by
physical vs. electrical size. Neither of those is dependent on a
BalUn. Now a BalUn as Choke may aid in pattern; and this is the
conventional failing point for J-poles. As for using a 4:1, what for?
Isn't the J-pole designed for a match already? If not, go a more
conventional route.

- I also note the J-Pole hairpin/matching section is never quite
balanced as the load Z at the connected vs non connected ends skews it
some. (From cebik) To my mind this has two thoughts, is it worth skewing
the feed point (eg one side of the feedpoint 1/2" below the other) and

Skewing, as you use it, is somewhat ambiguous. Moving the tap will
move the match, not the balance. Further, it will probably increase
what you perceive to be a problem.

does (static/lighting) grounding the supposed electrically neutral point
affect the efficiency/pattern of the thing.

It is actually, electrically grounded. Being neutral is a condition
of wavelength and distance. The combination of those two find a point
that is insensitive to attachment (there are folded dipoles that mount
this way).

- Wondering if feeding from one end results in ohmic losses reducing the
radiation from the upper element.

Ohmic losses will remain regardless of where you excite an antenna.
That is, unless you remove the loss. You don't say how you accomplish
THAT by moving the feed.

Thus skewing the pattern undesirably upwards.

A different skewing I see.

I heard this use to be a big problem with early UHF coaxial
collinear antennas. Mounting upside down was supposedly a good fix!

Yeh, sure.

- I had thought for ages that skying radiation from ground effects is

Skying? More skewing? Ground "effects?" An air dam for the bumper
of your antenna?

actually a function of the amount of radiation that goes at a downwards
angle. (ie a perfect antenna is one that doesn't radiate below the
"horizon" in free space)

Umm, perhaps.

If one uses a 5/8 element for the antenna's
mentioned above the normal high lobe one gets might contribute to this
problem.

5/8ths antennas were never built for problems, how did they suddenly
arrive at this juncture?

In other words is it better to (say) use 3x1/2 wave rather than
2x5/8 wave elements in either an EDZ or JPole setup. (I'll be modeling
this for my own interest but would appreciate feedback)

No. They are two distinctly different antennas. Note that 12/8ths
does not equal 10/8ths. Note even remotely.

- This of course begs the question as to whether one should even be
concerned about ground reflection on 2m with a 30ft mast!

Concerned? You sure have your priorities mixed. Maybe you should
dive right into modeling and resolve this through lifting a simpler
antenna through various elevations to find out what the consequences
are. They are many and varied.

73's
Richard Clark, KB7QHC