If you’ve ever wanted to do antenna matching with a VNA or give your board the option of an external antenna instead of the on-board one without adding a second footprint or any extra circuitry, this small connector type is worth knowing about.
A switchable RF connector looks like a normal miniature coax connector, but it has a mechanical switch built in. In its resting state, it connects your on-board signal path (e.g. to your PCB or chip antenna) straight through. The moment you plug something into it, the switch flips automatically and disconnects the on-board path, routing the signal to whatever you just plugged in instead. Unplug it, and it reverts back on its own.
Source: RF / Microwave Coaxial Connectors with Switch | Murata Manufacturing Co., Ltd.
That gives you two very practical options from a single footprint:
Testing: Plug in a mating probe connected to your VNA or spectrum analyzer to measure the actual performance at that point in your RF path without any extra switch, cable soldering, or board rework.
Antenna flexibility: Plug in an external antenna (e.g. on a pigtail) when you need more range or a different form factor and your on-board antenna is automatically taken out of the circuit. No firmware or hardware changes required.
I’ve been using Murata’s SWF series for this. It handles signals up to 6 GHz, which comfortably covers most sub-GHz IoT bands and is rated for 100 mating cycles which normally is enough for prototyping. Murata also offers smaller variants (SWG, SWH, SWJ) if you need higher frequency support or a tighter footprint. TE Connectivity sells compatible parts as well if you want a second source.
Link: RF / Microwave Coaxial Connectors with Switch | Murata Manufacturing Co., Ltd. (ordering code example: MM8130-2600, SWF series)
