I have a USB wireless dongle which I use with my laptop for 2.4 GHz IEEE802.11 connectivity. It has a sleeve dipole, in the form of a "rubberduck" antenna, which works well as an omnidirectional, but I want to use the laptop to communicate with a distant site, with low power.

I can build/buy a Yagi antenna, but would still like to use it with the USB dongle. Only problem I see is that the sleeve dipole presents an open circuit to the driver hardware (doesn't it?) while the driven element of a Yagi will be seen as a dead DC short.

Any advice on baluns, or other appropriate hardware between antenna and dongle would be most appreciated.

Cheers

Jim

 

Put a capacitor in series. No DC short. But what matters is the Impedence of the antenna at the operating frequency. It they are the same (normally 75, 300 ohms) no problem. A balun will be a 2:1 winding ratio for 75:300 ohm match. Use a ferrite ring.