In 3C43c.932$uh.753@fed1read02 (rec.radio.amateur.homebrew), Luhan Monat wrote:
Keith.fisher wrote:

Hello,
(Disclaimer - I am a novice electronics buff - just a few small
projects)
I have a small keychain remote used for advancing powerpoint slides.
It has an integrated laser pointer that is very useful in presenting
which is why I really want to get this to work.The remote is stated to
be 433 mhz. The reciever is a small box about the size of a pack of
cards.

[snip]

You may be better off putting a better antenna at the receiver end. The
optimum would be a 1/4 wavelength. Hey, anybody out there remember the
damn equation for this... 300,000 meters per second devided by
something-or-other???

A wavelength of 1 meter is a frequency of 300 MHz.

So 433 MHz will have a wavelength of (300/433) meters, or 9/13 meters.

A 1/4-wave antenna would be (1/4)*(9/13) meters long, which is 9/52
meters long -- which is just a teeny bit longer than 9/54 meters,
and that's 1/6 of a meter, or (1/6)* 39.37 inches, or just a smidgen
over 6.5 inches long -- and all that assumes I did the arithmetic
right. Since I'm a math jock, there's no guarantee I did, so check it
yourselves.

I just fired up the 4-banger calculator, and it tells me that the
1/4-wave antenna should be 6.819+ inches long, so 6.5 is a good
ballpark figure.

--
If anyone tells me to work smarter, not harder, I will kick him or her,
hard, in a random body part. I will then kick him or her a second time,
"smarter, not harder," which is to say that on the second strike, I'll
use the same force, but target more carefully. - Catherine, in a.s.r