What I read here no switch box will be needed.
The radio will pick the element that is most resident to the frequency your
scanner locks onto and will let you receive accordingly.

That's what I thought.
Thanks for the reply :-)

Dxluver ...

^ The radio will pick the element that is most resident to
^ the frequency your scanner locks onto and will let you
^ receive accordingly.

No. All signals from all elements are sent to the receiver. With a
transmitter, the signal will be sent to all elements but most of the
radiation will occur from the most resonate element.

Frank

No. All signals from all elements are sent to the receiver

Well then. What is the sense in building that antenna? Is this worth the
time? Is it going to make the signal sound like crap because if it is, I can
do that all by myself. :-)

Would you not agree that the element that is closest to resonance is also
the best match? With that as a given more signal is derived from that
element.

The radiation reception angle would also be lower. For example 2 elements,
one cut for 50 MHz and the other at 800 MHz. The 50 MHz element would appear
as a long wire on 800 MHz and would receive only signals directly overhead.

On frequencies above about 25 MHz, the best transmitting antenna for a
purpose is also the best receiving antenna for that same purpose.

The largest current will flow in a resonant antenna. We are interested in
developing the signal in microvolts across the fixed input impedance of the
receiver.

E=I/R meaning voltage is equal to the amount of current divided by the fixed
resistance of the receiver input. Increasing current then results in
increasing voltage, the holy grail to hear somebody. Note that ALL receivers
are characterized in microvolts required for a specific S/N ratio.

The other off resonance elements do not develop the necessary current
levels. They don't hurt anything, but are no real help. Ergo an element for
each band, either cut for a band or electrically cut by traps is a good way
to go.

Didn't mean to get so long winded...


"Frank" wrote in message
news:01c3d48e$08201270$0125250a@pixpqlbeqgavtlhm.. .
Dxluver ...

^ The radio will pick the element that is most resident to
^ the frequency your scanner locks onto and will let you
^ receive accordingly.

No. All signals from all elements are sent to the receiver. With a
transmitter, the signal will be sent to all elements but most of the
radiation will occur from the most resonate element.

Frank

Dxluver ...
^ No. All signals from all elements are sent to the receiver
^
^ What is the sense in building that antenna? Is this worth the
^ time?

It is true with ALL antennas. An antenna translates RF energy to electrical
energy, regardless of frequency. Frequencies that are close to resonant with
the antenna are more easily translated so their presence in the resulting
electrical signal is stronger. It is the receivers job to isolate the desired
frequency from the electrical signal.

Frank

w4jle ...

^ Would you not agree that the element that is closest to
^ resonance is also the best match?

No. Your question is phrased as a negative so my negative answer is an
agreement with the context of the question. I do not, not agree.

^ With that as a given more signal is derived from that
^ element.

Agreed.


^ The radiation reception angle would also be lower. For
^ example 2 elements, one cut for 50 MHz and the other at
^ 800 MHz. The 50 MHz element would appear as a long wire
^ on 800 MHz and would receive only signals directly overhead.

It works well. I assume you modeled the antenna with a software package and
that you used a vertical orientation. I use insulated wires that are
separated from each other only by the insulation. The wires are soldered
together at the BNC connector.


^ On frequencies above about 25 MHz, the best transmitting
^ antenna for a purpose is also the best receiving antenna
^ for that same purpose.

Graphically, the difference is like the difference between a 200m flagpole
and a 200m building. They both reach the same height -- the height
representing the "best" reception -- but the building covers a much greater
area, with the area representing the usable signal. In this analogy, the
flagpole is representing a transmit antenna and the building represents a
receive antenna.

So yes, the best transmit antenna is also the best receive antenna but the
receive has a much range that it is "best" at.



^ The largest current will flow in a resonant antenna. We are
^ interested in developing the signal in microvolts across the
^ fixed input impedance of the receiver.

The ability of an antenna to receive is irrespective of any electrical or
electronic equipment attached to it. An antenna captures electromagnetic
radiation and, if there is somewhere for it to flow, converts it to
electrical energy.


^ E=I/R meaning voltage is equal to the amount of current
^ divided by the fixed resistance of the receiver input.

That's E=I*R.


^ Note that ALL receivers are characterized in microvolts
^ required for a specific S/N ratio.

The ratio of desired frequencies to undesired frequencies.


^ The other off resonance elements do not develop the
^ necessary current levels.

That applies only when transmitting. When transmitting you are applying a
single frequency (plus and minus the bandwidth of the transmitter) to the
antenna system. In this case, the element that is most resonant will
translate most of that signal.

In the case of a receive antenna, the antenna is receiving ALL frequencies
and those that are close in wavelength to an element are received at a
greater level.

Frank

Whoops, sorry for the typo...

"Frank" wrote in message
news:01c3d51d$7bafea00$0125250a@ttakgbbprqsnyewb.. .
w4jle ...


^ E=I/R meaning voltage is equal to the amount of current
^ divided by the fixed resistance of the receiver input.

That's E=I*R.