Antenna design for tha 433MHz band.

Hi.

I'm designing a low power RF device with the CC1101 radio from texas instruments on the 433MHz band. I have some knowledge on transmission line theory but none on antenna theory, so i'm having difficulty answering some questions.

The device that i'm building has the area of a credit card and must have a range of at least 150m. This constrains are not making my life easy.

The questions that i have are; which antenna should i choose, a small helix or a monopole? How important is the ground plane size and its orientation relative to the antenna?

If anyone could give me some directions i would be very gratefull.

Thanks on advance.

Nuno

Dear Nuno
Hi
Did you tried a lambda/4 antenna for it ? it is excellent for your aim .
Best Wishes
Goldsmith

+12dBm output power and standard monopole antenna (helix or ground-plane) would be challenging to get a steady data link at 150m in 433MHz band, even assuming there is line-of-sight communication without any walls or objects between radios.