Hi, can anyone help me with this? I need to restrict sensitivity to a handheld keyfob to within about 5m and from a very narrow field in front of the antenna. It should be very insensitive behind the antenna. The RF frequency is 433.92Mhz. What would be the best directional antenna design for this. I thought about some kind of 'cantenna' design because it will need to be small in size but I haven't a clue where to start with the design. Any help would be greatly appreciated.