Additional response to OP jo9s8as at yahoo.com:

Using an MFJ259B with a #14 AWG (.064 dia) copper wire 19.4 inchs long stuck
into the antenna connector, I measured the following...

f = 146.5 MHz
R = 64 ohms, X = 65 ohms
both hands holding the MFJ

f = 146.5
R = 43 ohms, X = 60 ohms
one hand holding the MFJ

Sat the MFJ down on a brick wall about 3.5 feet high and moved away from it.

f = 146.5
R = 34, X = 44

Same location, adjusted for minimum SWR

f = 153 MHz
R = 61, X = 25

This last reading was a bit difficult as the readings changed with my body
location.

I could never determine the sign of the reactance for sure and I was never
able to adjust the frequency so that the reactance reading was lower than
about 25 ohms.

The MFJ enclosure is about 6.75 x 2.375 x 4 inches.

Cheers,
John

John - KD5YI wrote:
Additional response to OP jo9s8as at yahoo.com:

Using an MFJ259B with a #14 AWG (.064 dia) copper wire 19.4 inchs long stuck
into the antenna connector, I measured the following...


Andy comments,
John, your results would be more consistent, and more meaningful,
if you had some sort of ground plane in your experiments.

A wire, by itself, with nothing else, is like trying to light a lamp
with
only one prong plugged into the socket......

The radiating element, which you are measuring, has to have a
counterpoise (ground) to establish the Efield against and an Hfield
around.
In your setup, the housing of the MFJ, and your hand, and probly
other stuff, is the counterpoise, and the results are inconsistent.
I suspect that if you took a measurement, and started to pee on the
ground, the reading would change (grin).......Try it. But keep the
power low :))))

So, while your experiments may give you an idea of what the
resonant frequency and impedance of a piece of wire is, unless you
are able to take consistent, repeatable measurements, you can be
sure that something is not being accounted for..... My suggestion
is that you need a good counterpoise...... Maybe buy a sheet of
corrugated tin from Home Depot, mount the connector in the middle,
with the MFJ on one side and the antenna wire on the other.... You'll
find, I am certain, that your readings will be more consistent.....

This is not a bad ground plane for 2 meters --- I have used one
with good results......

It ain't magic, but there isn't any such thing as a unipole
radiator....

Good luck,

Andy W4OAH

"AndyS" wrote in message
oups.com...
The radiating element, which you are measuring, has to have a
counterpoise (ground) to establish the Efield against and an Hfield
around.

I believe that -- at least from a mathematical perspective -- "infinity" is a
perfectly good counterpoise. (Just as isolated conductors have capacitance to
infinity and inductors have "partial inductance" whereby a return path at
infinity is assumed.)

As a practical matter, of course the user's hands and other objects in the
environment will affect the measurement, but suggesting that "one must always
have a well-defined counterpoise" would tend to discourage one from studying
antennas that are less sensitive to counterpoises than those that are, and
this endeavor is quite valuable for the design of miniature antennas. After
all, there are millions of commercial devices in operation every day for which
the counterpoise is ill-defined.

My suggestion
is that you need a good counterpoise...... Maybe buy a sheet of
corrugated tin from Home Depot, mount the connector in the middle,
with the MFJ on one side and the antenna wire on the other.... You'll
find, I am certain, that your readings will be more consistent.....

This is not a bad ground plane for 2 meters --- I have used one
with good results......
==========================
Alternatively you could use a ground plane of chicken wire mesh ,a bit
easier to handle than a sheet of metal.

Frank GM0CSZ / KN6WH

Highland Ham wrote:
==========================
Alternatively you could use a ground plane of chicken wire mesh ,a bit
easier to handle than a sheet of metal.

Frank GM0CSZ / KN6WH

Andy comments:
That's a good idea. I always seem to have some tin laying around
and
no chicken wire, but it would work well. Also hardware cloth -- that
stuff
with the little squares that is used a lot on rabbit cage bottoms.....

In fact, they would both be good for corner reflectors, with a PVC
frame...
Or a large bowtie dipole to get broadband at VHF........ hmmmmmmmm.

Thanks Frank, you have ALMOST inspired me to start another
project........... maybe tomorrow :)))))

Andy W4OAH