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

I read in sci.electronics.design that Mike Andrews
wrote (in ) about 'Increasing range of rf
remote', on Mon, 8 Mar 2004:
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

Well, Catherine is misguided. People obviously want to minimise their
effort while preserving the quality and timing of the results.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

I read in sci.electronics.design that Mike Andrews
wrote (in ) about 'Increasing range of rf
remote', on Mon, 8 Mar 2004:
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

Well, Catherine is misguided. People obviously want to minimise their
effort while preserving the quality and timing of the results.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

Thanx all for the info on the antenna. I looked in the recever and
found the antena is *gasp* about 6.5 inches long!!! It is bent inside
the case into a square. So if I was to straighten and piont it straght
up would this help with range? Is the reason it is bent inside just to
hide and make the recever smaller or is it somehowe helping the
recever be omnidirectional? Agian - thanx for all the input!!!
KEith





[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.

Thanx all for the info on the antenna. I looked in the recever and
found the antena is *gasp* about 6.5 inches long!!! It is bent inside
the case into a square. So if I was to straighten and piont it straght
up would this help with range? Is the reason it is bent inside just to
hide and make the recever smaller or is it somehowe helping the
recever be omnidirectional? Agian - thanx for all the input!!!
KEith





[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.