Electrically small quasi isotropic extendable antenna
The present invention discloses an extendable antenna for a portable communication device, made of two radiating wires each shaped as an open loop; a first loop fixed and a second loop movable between two positions: in parallel or alternatively vertically to the first loop; the parallel position suitable for compactly carrying the device in non-active mode, and the vertical combination configured to produce a substantially isotropic radiation pattern, particularly instrumental for satellite communications. According to one embodiment, this device is a satellite served Personal Locator Beacon (PLB) for Search and Rescue (SAR) of people in distress, configured to be wrist worn.
1. A portable communication device comprising an extendable antenna, said antenna comprising a first substantially planar radiating element, a second substantially planar radiating element, a feeding conductor and a ground plane; the feeding conductor configured substantially perpendicular to said ground plane and coupled to both said radiating elements, electrically in parallel; said first radiating element configured geometrically in parallel to said ground plane, and said second radiating element configured to move between two positions: a) stowed, in which said second radiating element is substantially parallel to said first radiating element; b) operational, in which said second radiating element, wherein:
a. said first and second radiation elements configured to resonate at a substantially similar frequency;
b. said radiating elements configured such that the superposition of their radiation patterns will form a substantially isotropic radiation pattern;
c. said ground plane being a metallic surface part of said portable device.
2. A device according to claim 1 , wherein at least one of said radiating elements configured as a conductive wire in shape of an open loop.
3. A device according to claim 2 , wherein said ground plane and said loop configured in substantially similar external dimensions.
4. A device according to claim 3 , wherein any of said external dimensions is smaller than 10% of a wavelength at which said device is tuned to communicate.
5. A device according to claim 1 , further configured with a short conductor electrically connecting said ground plane with said first radiating element.
6. A device according to claim 1 , further comprising a hinge by the feeding conductor, configured to enable the second radiating element rotating in 90 degrees from vertical to horizontal position.
7. A device according to claim 1 , further comprising a display, placed above said ground plane, and said second radiating element configured not to obstruct the display in stow position.
8. A device according to claim 1 , wherein at least one of said radiating elements is configured on a printed circuit board (PCB).
9. A device according to claim 1 , further comprising a radio been at least one of: receiver, transmitter; said radio placed on said ground plane and coupled to said feeding conductor.
10. A device according to claim 1 , configured to be worn, wherein said ground plane configured to be placed between said first radiating element and the human body.
11. An extendable antenna, comprising a first substantially planar radiating element, a second substantially planar radiating element, a feeding conductor and a ground plane; the feeding conductor configured substantially perpendicular to said ground plane and coupled to both said radiating elements electrically in parallel; said first radiating element configured geometrically in parallel to said ground plane, and said second radiating element configured to move between two positions: a) stowed, in which said second radiating element is substantially parallel to said first radiating element; b) operational, in which said second radiating element is substantially perpendicular to said first radiating element, wherein:
a. said first and second radiation elements configured to resonate at a substantially similar frequency;
b. said radiating elements configured such that the superposition of their radiation patterns will form a substantially isotropic radiation pattern.
12. An antenna according to claim 11 , wherein at least one of said radiating elements configured as a conductive wire in shape of an open loop.
13. An antenna according to claim 12 , wherein said ground plane and said loop configured in substantially similar external dimensions.
14. An antenna according to claim 13 , wherein any of said external dimensions is smaller than 10% of a wavelength at which said antenna is tuned to radiate.
15. An antenna according to claim 11 , further configured with a short conductor electrically connecting said ground plane with said first radiating element.
16. An antenna according to claim 11 , further comprising a hinge by the feeding conductor, configured to enable the second radiating element rotating in 90 degrees from vertical to horizontal position.
17. An antenna according to claim 11 , further said second radiating element configured not to obstruct the center part of said ground plane in stow position.
18. An antenna according to claim 11 , wherein at least one of said radiating elements is configured on a printed circuit board (PCB).
19. An antenna according to claim 11 , configured to be coupled to a personal communication device.
20. An antenna according to claim 11 , configured to communicate with remote antennas onboard satellites orbiting around the earth.