hi I want to make a remote control key click device using TLP434A ,can someone guide me on how to make a pcb loop antenna for it ?
Try Googling “pcb antennas 433MHz”. One vendor, Linx, sells a prebuilt one called a [Splatch. Other links returned by the Google search discuss the electrical considerations for such an antenna. A quarter wave antenna at 433MHz is about 6", so the antenna will be larger than for a 2.4GHz transmitter.](http://www.linxtechnologies.com/index.php?section=products&category=antennas&subcategory=embeddable&series=sp_series)
but how do they use these chipcs in key chains if they need 6inch antenna?
The antenna in a formed in a spiral loop which reduces the space required.
It is also possible to use an inductor to reduce the size of the antenna like the personal FRS/GMRS radios do. The performance of these types of antennas are not as good as a straight quarter wave antenna, but are sufficient for short range communications.