In article
s.com, robgraham scribeth thus
On Jun 13, 8:48*am, Andy Burns wrote:
Tim W wrote:
an aerial is just a length of metal I think

Sometimes with embedded voodo, the ones embedded within laptop screens
especially so.

Am I right in thinking I can leave the insulation on a length of copper wire
and use that? Will the length I cut it at make a difference? I mean
obviously it will be longer, maybe 30" instead of 3" but does it have to be
a multiple of a wavelength or something?

Usually 1/4 or 1/2 wavelength, but that'll be what you already have

http://www.fpvuk.org/forum/index.php?topic=1391.0

I am guessing the aerial can be
thin - a coat hanger not necessary here - but is solid copper better than
strands?

What's the velocity factor of a coathanger?

If you want to make existing access point more directional, you could
try this

http://www.freeantennas.com/projects/Ez-10/

I get similar moans from my son whose pc is at the other end of the
house and having been in electronics, though not RF, can at least do
all the making part.

I read through the links and was rewarded at least in understanding
why a coat hanger might have a velocity factor :) - no doubt this
factor was mentioned in my training all too many years ago now.

Two questions - why does the designer of the aerial on the FPV forum
not take the velocity factor into account, and why does it only apply
to the 'folded' back section - I can't see that the 'bazooka'
configuration is any different electrically?

Rob


The velocity factor is the slowing of a Radio frequency signal in a
metal as In metals they travel slower than free space...

Its all there on goggle...

--
Tony Sayer