Electronic – RF Switch vs Zero-Ohm Resistors


Does anyone have any experience using zero-ohm resistors in an RF signal path to select antennas? I've typically used RF switches for this purpose, but that's also when it was necessary to allow the antenna selection to be changed "in the field". But for cases where the antenna selection is a manufacture-time option, I'm considering simple zero-ohm resistors (i.e. populating one or the other to complete the particular signal path to the antenna).

Of course using zero-ohm resistors for this sort of thing in a digital circuit path is a no-brainer, but I'm specifically interested if there is anything I should watch out for since this is an RF path (two separate paths: 868-915MHz and 2.4GHz). Can I treat the zero-ohm resistor as essentially being part of the PCB trace, or will this cause problems?

PS – The two antenna path options are an on-board ceramic antenna and an off-board connector. The zero-ohm resistor would be a surface-mount component.

Best Answer

You rarely need DC continuity to an antenna, so I've always used a normal SMD 10pF to 100pF ceramic capacitor, depending on frequency. They're already used on the board, and tend to be cheaper than zero-ohm resistors, as we buy them by the bazillion rather than the handful.