hi

i was just reading about airforce plans that had a trailing wire which
when fully extended was 6miles long


i was just wondering given that environment and assuming a few
varied yet unknown frequencies...


how well does such a antenna work, when assuming it is multiple
waves long?? i mean does anyone know from first hand experience how
they worked?? good bad?? just talking signal wise


i can extrapolate technically how it 'ought' to work but wonder




thanks

ml wrote:
how well does such a antenna work, when assuming it is multiple
waves long??

It works similar to a rhombic.
--
73, Cecil http://www.w5dxp.com

multiple wavelengths?? why would you assume that??

"ml" wrote in message
...
hi

i was just reading about airforce plans that had a trailing wire which
when fully extended was 6miles long


i was just wondering given that environment and assuming a few
varied yet unknown frequencies...


how well does such a antenna work, when assuming it is multiple
waves long?? i mean does anyone know from first hand experience how
they worked?? good bad?? just talking signal wise


i can extrapolate technically how it 'ought' to work but wonder




thanks

This may be - to communicate with submarines (VLF).
So your assumption that its multiple wavelengths long may be unwarranted.
It may be a quarter-wave, half-wave or any portion (or multiple) of a
wavelength.
..

"ml" wrote in message
...
hi

i was just reading about airforce plans that had a trailing wire which
when fully extended was 6miles long


i was just wondering given that environment and assuming a few
varied yet unknown frequencies...


how well does such a antenna work, when assuming it is multiple
waves long?? i mean does anyone know from first hand experience how
they worked?? good bad?? just talking signal wise


i can extrapolate technically how it 'ought' to work but wonder


This may be - to communicate with submarines (VLF).

In article 2JJVj.121$Pr1.106@trndny03, "Dave"
wrote:

multiple wavelengths?? why would you assume that??

"ml" wrote in message
...
hi

i was just reading about airforce plans that had a trailing wire which
when fully extended was 6miles long


i was just wondering given that environment and assuming a few
varied yet unknown frequencies...


how well does such a antenna work, when assuming it is multiple
waves long?? i mean does anyone know from first hand experience how
they worked?? good bad?? just talking signal wise


i can extrapolate technically how it 'ought' to work but wonder




thanks

i didn't assume anything, it was clearly stated in certain articles
about that, that the antenna was realled out to different lengths
dependind on things some of which were frequency


thanks Cecil

"Hal Rosser" wrote in message
...
This may be - to communicate with submarines (VLF).
So your assumption that its multiple wavelengths long may be unwarranted.
It may be a quarter-wave, half-wave or any portion (or multiple) of a
wavelength.
.

"ml" wrote in message
...
hi

i was just reading about airforce plans that had a trailing wire which
when fully extended was 6miles long


From:

http://jproc.ca/radiostor/vlfelf.html

In the United States military, the primary means of communicating with
submerged submarines is the TACAMO (Take Charge and Move Out) system which
uses a fleet of aircraft. Two aircraft are always airborne - one over the
Atlantic and one over the Pacific. Other aircraft are stationed on the
ground and they are on a 15 minute alert. The aircraft fly 10.5 hour
missions, starting at one airfield and ending at another. Random patterns
are flown to mislead any unauthorized observers. The TACAMO aircraft can
receive and relay signals from a number of different ground command posts.
Each aircraft is equipped with a 6.2 mile long trailing wire antenna (wound
on a reel) and a 100 kw transmitter operating in the VLF region. When the
aircraft has to transmit a message, it banks and proceeds to fly a very
tight circle. The causes the trailing wire antenna to hang vertically below.
Once the message is transmitted over the VLF downlink the aircraft resumes
normal flight.
The TACAMO fleet was initially comprised of the Lockheed Hercules EC130
aircraft, but these are being gradually phased out and replaced with the
Boeing 747 AWACS type aircraft. These aircraft have the capability to
transmit a 200 kw signal using a 2.5 mile trailing antenna. The systems
described above were documented in a book printed in 1985. Due to
unavailability of information, I do not know if the same system is still in
use in the 1990's, but the techniques, nonetheless are quite intriguing.

..

The TACAMO fleet was initially comprised of the Lockheed Hercules EC130
aircraft, but these are being gradually phased out and replaced with the
Boeing 747 AWACS type aircraft. These aircraft have the capability to
transmit a 200 kw signal using a 2.5 mile trailing antenna. The systems
described above were documented in a book printed in 1985. Due to
unavailability of information, I do not know if the same system is still
in use in the 1990's, but the techniques, nonetheless are quite
intriguing.


Very interesting indeed.
We know that uhf and vhf are for the most part, line-of-sight communication,
with exceptions like ducting, etc...
But it would be interesting to experiment with vlf, to see what it
penetrates.

Speaking of the trailing wire - I wonder if you could trail a loop - and use
it to generate electricity from cutting earth's magnetic lines of force -
(perhaps to power the aircraft after its up to speed. I think they
experimented with the idea on one of the shuttle's orbital missions, but
didn't hear much about the results.

On Tue, 13 May 2008 00:19:50 -0400, "Jimmie D"
wrote:



Speaking of the trailing wire - I wonder if you could trail a loop - and
use it to generate electricity from cutting earth's magnetic lines of
force - (perhaps to power the aircraft after its up to speed. I think they
experimented with the idea on one of the shuttle's orbital missions, but
didn't hear much about the results.




I think I remember hearing the experiment worked too well and they had a lot
of uncontrolled arcing.
I wonder how much drag this would put on the shuttle.

Jimmie

The wire cutting through the magentic field will generate an EMF - a
potential difference between one end of the wire and the far end but
there is no complete circuit to tap it. If a return wire were
connected to the far end of the wire, it would generate the same value
and polarity giving no net emf (voltage) around the path. If one
could create a loop and rotate it in the field that would be a
different matter. The same concept applies to the voltage developed
between the wing tips of a (metal) aircraft.

Jimmie

The wire cutting through the magentic field will generate an EMF - a
potential difference between one end of the wire and the far end but
there is no complete circuit to tap it. If a return wire were
connected to the far end of the wire, it would generate the same value
and polarity giving no net emf (voltage) around the path. If one
could create a loop and rotate it in the field that would be a
different matter. The same concept applies to the voltage developed
between the wing tips of a (metal) aircraft.


My post was about a possible trailing loop. (Both ends accessable to the ham
on board.)
You don't have to rotate the loop - just to move it.
The aircraft is moving - thus the magnetic lines get 'cut' so to speak, so
emf gets generated.
I also heard it worked 'too well' on the shuttle - that the current was so
great that the wire burned into.

Hal Rosser wrote:
Jimmie


The wire cutting through the magentic field will generate an EMF - a
potential difference between one end of the wire and the far end but
there is no complete circuit to tap it. If a return wire were
connected to the far end of the wire, it would generate the same value
and polarity giving no net emf (voltage) around the path. If one
could create a loop and rotate it in the field that would be a
different matter. The same concept applies to the voltage developed
between the wing tips of a (metal) aircraft.



My post was about a possible trailing loop. (Both ends accessable to the ham
on board.)
You don't have to rotate the loop - just to move it.
The aircraft is moving - thus the magnetic lines get 'cut' so to speak, so
emf gets generated.
I also heard it worked 'too well' on the shuttle - that the current was so
great that the wire burned into.


you can get charging and arcing in orbit from lots of other sources
(impact with charged particles, for instance). It's a pretty big issue
with large things like ISS that can build up substantial charge if
things aren't bonded together. More than one spacecraft has been lost
due to this kind of thing (Japan's Midori-2 is one case I know of).
http://www.space.com/spacenews/archi...ch_111103.html

Jim