foxbrain wrote:

'Helmut Wabnig[_2_ Wrote:
;793671']On Thu, 19 Jul 2012 23:20:02 +0000, foxbrain
wrote:
-

hi
i'm just new to this field and i need some help on it and i appreciate
any help...
my aim is to make a 315 or 433 transmitter and receiver so what ics is
the best for that and where can i buy them and so for the antennas(but i
would like to build them)...
thanks-


For the antenna use a piece of wire, a length of lamda/4 is fine.

w.

is it a straight wire or curved ? shouldn't i look at it's impedance and
make matching with it ?
what about it's ICs

If you want meaningfull replies, you need to ask meaningfull questions.

What do you intend to transmit, modulation type, power levels, etc.?

i want to make a remote control for 3 relays using the encoders/decoders: pt2262 and pt2272 , it doesn't mine what kind of modulation...
i recently found these 2 ics : u2741b and ata3741 . but what kind of antenna do i need? is there any other thinks i have to know?

On Sat, 21 Jul 2012 14:02:29 +0000, foxbrain
wrote:


i want to make a remote control for 3 relays using the
encoders/decoders: pt2262 and pt2272 , it doesn't mine what kind of
modulation...
i recently found these 2 ics : u2741b and ata3741 . but what kind of
antenna do i need? is there any other thinks i have to know?

Yes, thinkalot.

Why not buy such a thing as this he

http://tinyurl.com/c2pku44


w.

foxbrain wrote:

i want to make a remote control for 3 relays using the
encoders/decoders: pt2262 and pt2272 , it doesn't mine what kind of
modulation...
i recently found these 2 ics : u2741b and ata3741 . but what kind of
antenna do i need?

How would anyone here know that as it depends on what kind of range you
exepect to get.

The simplest antenna would be a quarter wavelength piece of wire.

is there any other thinks i have to know?

Probably.

thanks that helped...
BTW i'm making a project for my own not any kind of homework.
i have one more question : if i wanted to make my device have a bigger range like 500-1000meters should i put an amplifer before the antenna?
i should change the antenna in to yagi shouldn't i?

On Mon, 23 Jul 2012 00:08:53 +0000, foxbrain
wrote:

BTW i'm making a project for my own not any kind of homework.

Ok, you're off the hook.

i have one more question : if i wanted to make my device have a bigger
range like 500-1000meters should i put an amplifer before the antenna?
i should change the antenna in to yagi shouldn't i?

FCC 15.209
http://louise.hallikainen.org/FCC/FccRules/2012/15/209/
200 uv/meter maximum, measured at 3 meters. That works out to about
-46dBm ERP or about 12 milliwatts into a unity gain antenna.

This should explain how it all works:
http://transition.fcc.gov/Bureaus/Engineering_Technology/Documents/bulletins/oet63/oet63rev.pdf
See the calcs on Pg 29.

Claims 500 meters:
http://www.sparkfun.com/products/155
At 10mw, this is close to maximum legal. Anything more than that and
you're going to start interfering with wireless weather stations, car
alarms, etc.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Sun, 22 Jul 2012 23:21:12 -0700, Jeff Liebermann
wrote:

FCC 15.209
http://louise.hallikainen.org/FCC/FccRules/2012/15/209/
200 uv/meter maximum, measured at 3 meters. That works out to about
-46dBm ERP or about 12 milliwatts into a unity gain antenna.

Sorry, brain damage.
The -46dBm should be 10.8dBm ERP

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

so depending on the equation in :
http://transition.fcc.gov/Bureaus/En...3/oet63rev.pdf
i should make the power the much larger i can but not more than 10mw
and so for the gain , and decrease the E (v/meter)....
thanks

On 7/23/2012 1:28 AM, Jeff Liebermann wrote:
On Sun, 22 Jul 2012 23:21:12 -0700, Jeff Liebermann
wrote:

FCC 15.209
http://louise.hallikainen.org/FCC/FccRules/2012/15/209/
200 uv/meter maximum, measured at 3 meters. That works out to about
-46dBm ERP or about 12 milliwatts into a unity gain antenna.

Sorry, brain damage.
The -46dBm should be 10.8dBm ERP


Hmmm... my calculator says P = 12 nanowatts.