RadioBanter - DOUBLE RESONANCE IN DIPOLE...THE CAUSE?????

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- - DOUBLE RESONANCE IN DIPOLE...THE CAUSE????? (https://www.radiobanter.com/antenna/2561-double-resonance-dipole-cause.html)

Cecil Moore wrote in message ...
Dr. Slick wrote:
What if the resonant frequencies are 88.1 and about 92.0 MHz?

Log Periodic?

Or perhaps a discone of some sorts, sure.

But we are talking about a simple dipole here.

S.

Richard Clark wrote in message . ..

A broadband antenna usually doesn't have as good a
match as a dedicated antenna.

You have too little exposure to the world of antennas to paint them
with that broad brush. A simple example is a discone antenna which is
a variant of the biconical antenna, which is the genesis of ALL
dipoles. Either the discone or the biconical display a very wide
bandwidth (octaves) and are eminently matchable by definition.

I'll bet you money that a well designed, dedicated, tunable
antenna can achieve a better SWR than any discone.

There are broadband folded dipoles for VHF,
but you don't get something for nothing! They may
be adequate across the band, but nothing beats
a dedicated antenna.

Again, didn't need a choke for this one.

You have yet to show that it is not your problem, much less the lack
of need (which is a strict requirement for tuning). "Not needing" it
can be accomplished through one of two means:
Luck,
or
a hardwired solution (the customer, like with CB whips, cannot
vary the length without causing a major shift in dynamics).
Either way, the two are probably the same solution, an even halfwave
multiple length line. The longer the line, the more tenuous the
solution.

Neither. We have varied the coax length, certainly not
keeping to multiples of 1/2 wavelength, with results
remaining the same. We just don't need it with our
design.

Someone infered the first problem, not high
above off the ground.

So what was the second thing i did?

S.

Richard Clark wrote in message . ..

What do you grow in your garden?

http://www.marijuanaaddiction.info/i...d%20plants.jpg

S.

"Dr. Slick" wrote in message
om...
Cecil Moore wrote in message
...
Dr. Slick wrote:
What if the resonant frequencies are 88.1 and about 92.0 MHz?

Log Periodic?

Or perhaps a discone of some sorts, sure.

But we are talking about a simple dipole here.

All this sounds like the characteristics of a dummy load......

Dr. Slick wrote:
There are broadband folded dipoles for VHF,
but you don't get something for nothing! They may
be adequate across the band, but nothing beats
a dedicated antenna.

Here's something for virtually nothing. Take a
commercial FM folded dipole, vary the feedline length,
and you have a tunable folded dipole peaking at your
frequency of choice. The tuning can be done by mounting
two telescoping antenna sections side-by-side.
--
73, Cecil, W5DXP

Nilla Wafer wrote:
"Were the two halves of the dipole of equal length?"

The adjacent close-spaced wire ends have much mutual resistance and in
most cases there os a considerable conductance between them too. In
these cases, they resonate as a unit. But, imbalance enhaces radiation
from the feedline which can produce a separate resonance.

Best regards, Richard Harrison, KB5WZI

Dr. Slick wrote:
"They (terminated folded dipoles) may be adequate across the band, but
nothing beats a dedicated antenna."

A rhombic will clean your clock.

Best regards, Richard Harrison, KB5WZI

Richard Clark wrote:
However, out stellar designer has managed to negate that through a
"marijuana garden variety dipole" with radials. ;-)

Radials? I missed that. How are the radials coupled to
the dipole?
--
73, Cecil, W5DXP