Buy on Amazon : http://www.amazon.com/gp/product/B0010CIIJM?tag=lottalatte-20

Sennheiser A1031-U Wideband Passive Omnidirectional UHF Antenna for Evolution Series

Suitable for use with a UHF receiver in closed rooms
Can be used as a transmitting device
Suitable for use with EM 3031-U EM 3032-U EM 3532-U EM 1046-U EM 1031-U and all stationary evolution wireless receivers