An antenna arrangement for dual mode radio devices such as WCDMA/GSM or
Bluetooth radio devices. The arrangement contains two antennas close to
each other, where a shorting switch is used at an open end of one antenna
to increase isolation by effectively converting the one antenna from a
quarter wave length antenna to a half wave length antenna when not needed
in order to improve the efficiency of the other antenna. The shorting
switch is typically a MEMS switch and the antennas are typically PIFA
antennas. A radio device containing the arrangement has also been
disclosed.