Do I need a Balun for very short range?

[Charles]

I'm using a 51422 for a very short range, fixed system. I will never need the chip to receive or be received from more than 5 meters away, and more often just 2-3 meters. On my custom PCB the two antenna pins (ANT1, ANT2) are unconnected and facing the edge of the board, with a ground plane under the 51422 on the opposite side of the PCB. The reference design on the site seems to assume that builders want maximum transmission distance. Since my range is so short, do I need a Balun or an antenna at all? Or is the fact that the chip is on the edge of the board with no obstructions good enough?

[RK]

Of course you need an antenna, and you need it to be matched at least minimally to the correct impedence. Even if you have an antenna and have it poorly balance you'll find 5m to be a long distance, with no antenna at all you will have a range of 0mm.

[Charles]

Thank you very much! I will start looking at the reference design now.

[Roger Clark]

You can compress the antenna size, e.g. use a zig-zag type track shape but still have matching impedance, but the more compressed the antenna the shorter the range is likely to be.