The present invention discloses a portable personal communication device with an extendable helical antenna. This helical antenna is made of an elastic conductive spring, configured to change its height over a ground plane and along the antenna axis, mainly having two positions: a stowed position where the antenna is pressed down between the ground plane and a rigid cover, achieving a low profile; and an operational position where the rigid cover is removed and the antenna is extended by its own spring force, to a higher height, improving antenna gain. Normally, a second planar antenna may be placed over the same ground plane, not exceeding the footprint of the helical antenna, thus utilizing a compactly small volume and yet achieving a considerable electromagnetic decoupling between the antennas, due to their different radiation patterns. According to one embodiment, these antennas are installed in a Personal Locator Beacon (PLB) for Search and Rescue (SAR) of people in distress, where the planar antenna is coupled to a Global Navigation Satellite System (GNSS, such as GPS) receiver, and the helical antenna is coupled to a VHF/UHF radio.