Licence plate antenna

The diversity licence plate antenna – yes folks it’s all about how to use the registration plates on your vehicle to radiate your ham radio signal.

There’s an interesting article in the May edition of CQ Magazine headlined ‘Invisible Mobile Installation’ by Scott Williamson VY1SW who wanted to use 2m and 70cm mobile, without drilling a hole or using an on-glass antenna.

The simplest thing about the project is a splitter box made by US Communications that has three BNC connectors, one for the transceiver and two others go to the front and rear number plates.

But man ‘o man, Scott VY1SW who was keen to have a disguised antenna on his brand new, red coloured Infiniti G37 Coupe, is pictured removing both the front and rear bumper bar skins to install the feed line and connections.

It required removing bolts, screws and clips, remembering where they go and in what order to correctly put it all back together again, plus the removal of some internal panels for cabling.

When completed, the number plates essentially act as two dipoles, and connected to the diversity control box, the signal is divided between them providing optimal transmission.

The box even provides impedance matching and has a phasing element to achieve diversity reception, so the signals received via the number plates are additive rather than cancelling.

Jim Linton VK3PC

Wireless Institute of Australia