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.