On Mon, Feb 23, 2009 at 10:48 AM, Lan Barnes <l...@falleagle.net> wrote:
>
> On Sun, February 22, 2009 8:15 pm, Carl Lowenstein wrote:
>> On Sat, Feb 21, 2009 at 7:14 PM, Gus Wirth <gwirt...@gmail.com> wrote:
>>> Lan Barnes wrote:
>>>> I suspect the reflector from a large flashlight would do the job as
>>>> well.
>>>
>>> Probably not unless the reflector came a really old flashlight and is
>>> made entirely of metal. Modern flashlights have reflectors made of
>>> plastic with a very thin aluminum coating. The coating isn't thick
>>> enough to be a good reflector of RF.
>>
>> Flashlight reflectors are really not big enough. Remember, the
>> wavelength is about 4.5 inches.
>>
>
> Would that be the radius or diameter? I have a flashlight reflector about
> that diameter. Even if it's plastic, it could be lined with foil. And it
> had a hole for the antenna and is guarenteed to be a parabola.
You can't position the circular flashlight reflector or the stove
burner drip pan to reflect from the linear antenna that most WAPs
have.
The drip pan would work really well with a point-source wireless
device like a USB wireless dongle. Somewhere on the web I have seen a
picture of such a device.
>> Go see freeantennas.com and look at the linear parabolic antennas made
>> to match the linear antenna that sticks out of your wireless access
>> point. I have been using their cardboard and aluminum foil model for
>> a few years.
>
> Yes, they have planar parabolas as opposed to circular.
>
> Question: does surface-crinkled foil mess it up? My guess is yes, it
> scatters it.
You aren't thinking about the complete CB route of recycling used foil, are you?
The crinkles are small compared to the wavelength, and might diffuse
the focus a bit. I used a cardboard file folder cut to size, and
glued foil cut from a Reynolds Wrapper onto its back side after
bending to the parabolic shape. The reflector is about 4 inches high,
matcning the length of the antenna, and 6 or 7 inches wide.
(hand-waving size measurement)
I had a two-antenna Linksys box, and built two reflectors. When I
changed over to a single-antenna Netgear, I put one of the reflectors
away in a safe place. If I could only find the safe place again I
would give you the reflector to try.
carl
--
carl lowenstein marine physical lab u.c. san diego
clowenst...@ucsd.edu
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