Patent ID: 6278415
Filing Date: 2001-08-21
Classification: H01Q

Abstract:
A multi-filar helical antenna, comprising:an antenna radiant section which comprises n elements which are wound in spiral;two feeding lines which are connected to said antenna radiant section and have substantially a same electrical line length;a switch having an input terminal connectible to receive an I/O signal thereon and a first selectible output terminal and a second selectible output terminal;a 3 dB hybrid having four terminals, said four terminals of said hybrid including a first input side terminal connected to said first switch output terminal and a second input side terminal connected to said second switch output terminal, a first output side terminal connected to one of said feeding lines and a second output side terminal connected to the other of said feeding lines, whereby said switch determines radiant directivity of said antenna radiant section according to whether said switch connects its said input terminal to its said first selectible output terminal whereupon said radiant section is oriented along a first directivity, or whether said switch connects its said input terminal to its said second selectible output terminal whereupon said radiant section is oriented along a second directivity, different from said first directivity;terminating circuits including a first terminating circuit electrically connected between said first switch output terminal and said hybrid's first input side terminal for terminating signals from said hybrid's first input terminal when said switch connects its said input terminal to its said second selectible output terminal, and a second terminating circuit electronically connected between said second switch output terminal and said hybrid's second input side terminal for terminating signals from said hybrid's second input terminal when said switch connects its said input terminal to its said first selectible output terminal.