That's right - a bolt of lightning comes streaking across several miles of
dry air, finds the antenna with no problem, then upon seeing the loop, ducks
back into the ground.
But at least the loop will make the rain drip outside. It not useless.


"w_tom" wrote in message
oups.com...
Do you think a loop will stop what three miles of sky could not?
Effective protection is not about stopping a transient. That does not
work and is they myth even used to promote plug-in protectors. A most
trivial earth ground is a massive improvement in protection. That
incoming wire must be earthed - directly or through a protector -
before entering the building. That simplest earthing is many times
more effective than 100 loops. Effective for direct strkes - which
means induced trasnients would be made irrelevant.

The US Forestry Service has documented that most direct strikes to
trees do not leave appreciable indication. Even a standard household
earth ground in conductive soil will provide protection from most
lightning strikes. Then we enhance that earthing for other, more
violent and less frequent direct strikes.

Quality of earthing determines how many direct strikes will be
earthed without damage. Even some earthng to a single point is a
massive improvement in transistor protection. But the loop is about
as useful as bad science fiction. For loop to be effective, then loop
also must seriously degrade radio reception. How many reasons why that
loop is useless? Five?

Robert11 wrote:
Hello:

Anyone have any thoughts on (hopefully not experiences) whether putting
a
loop of, e.g. 1 foot in diameter,
on a coax run from an outdoor receive-only antenna has any merit as far
as
helping any emf lightning induced pulses from traveling into a house ?

Have heard about this, but it's hard to believe it would actually do
anything in practice.
But,... ?

B.

In article ,
"Hal Rosser" wrote:

That's right - a bolt of lightning comes streaking across several miles of
dry air, finds the antenna with no problem, then upon seeing the loop, ducks
back into the ground.
But at least the loop will make the rain drip outside. It not useless.


I've read that most of the lightning starts at the ground first and
reaches into the sky to find the other end.









"w_tom" wrote in message
oups.com...
Do you think a loop will stop what three miles of sky could not?
Effective protection is not about stopping a transient. That does not
work and is they myth even used to promote plug-in protectors. A most
trivial earth ground is a massive improvement in protection. That
incoming wire must be earthed - directly or through a protector -
before entering the building. That simplest earthing is many times
more effective than 100 loops. Effective for direct strkes - which
means induced trasnients would be made irrelevant.

The US Forestry Service has documented that most direct strikes to
trees do not leave appreciable indication. Even a standard household
earth ground in conductive soil will provide protection from most
lightning strikes. Then we enhance that earthing for other, more
violent and less frequent direct strikes.

Quality of earthing determines how many direct strikes will be
earthed without damage. Even some earthng to a single point is a
massive improvement in transistor protection. But the loop is about
as useful as bad science fiction. For loop to be effective, then loop
also must seriously degrade radio reception. How many reasons why that
loop is useless? Five?

Robert11 wrote:
Hello:

Anyone have any thoughts on (hopefully not experiences) whether putting
a
loop of, e.g. 1 foot in diameter,
on a coax run from an outdoor receive-only antenna has any merit as far
as
helping any emf lightning induced pulses from traveling into a house ?

Have heard about this, but it's hard to believe it would actually do
anything in practice.
But,... ?

B.

Steve wrote:
"I wouldn`t think anything but extremely good grounding at the antenna
will do much."

That helps.

Company I retired from had radios all over the world. Most base stations
used Andrew 1/4-wave stainless steel folded monopoles. These were
securely grounded to the tower. The tower had a separate ground rod
connected outside the base to each leg of the tower by heavy strap or
cable. These radios suffered no lightning damage, despite repeated hits.

Kraus has this to say in kis 3rd edition of "Antennas" on pages 719 and
720:
"---a short-circuited lambda/4 section of coaxial line is connected in
parallel with the antenna terminals. This widens the impedance bandwidth
and also places the stub antenna at dc ground potential. This is
desirable to protect the transmission line from lightning surges."

Whenever we could not use a folded antenna with a single-frequency
radio, we connected the shorted stub directly across the antenna and
grounded the coax at the tower top. It works.

Best regards, Richard Harrison, KB5WZI