antenna-theory.com

[Jimbo54]

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

[admin]

Dipole is open circuit at DC. At 2.4GHz it has 50 Ohms impedance. The key is to ensure at 2.4GHz the impedance of your antenna is close to 50 Ohms (equivalent to saying low VSWR). http://www.antenna-theory.com/definitions/vswr.php

The radio generally doesn't care if the antenna is open or short circuit at DC. There is some advantage to having short circuit at DC for ESD protection. Many antennas such as IFAs, slots, PIFAs are short at DC.

A yagi, with its driven element can be a dipole (open at DC) or folded dipole (short at DC), but I don't think it will affect you.

[RashiR]

Yagi-Uda Antenna has a great advantage of adjustable gain from moderate to high gain.