Abstract: A dual band multi-pitch helical antenna (101) includes a first section (201) positioned adjacent to the feed point having a widely spaced pitch. A second section (203) is attached to the first section (201) having a narrowly spaced pitch. A third section (205) is attached to the second section (203) having a widely spaced pitch, while a fourth section (207) is attached to the third section (205) having a narrowly spaced pitch. The antenna further includes a parasitic element (213a/213b) that is positioned adjacent to each of the first section (201), second section (203), third section (205), and fourth section (207) for enhancing broad-band antenna performance. A matching network (216) is connected between an antenna feed point and the first section (201) for matching the dual band multi-pitch helical antenna to a predetermined feed point impedance such that the antenna is resonant in at least two frequency bands.

Abstract: A dual band multi-pitch helical antenna (101) includes a first section (201) positioned adjacent to the feed point having a widely spaced pitch. A second section (203) is attached to the first section (201) having a narrowly spaced pitch. A third section (205) is attached to the second section (203) having a widely spaced pitch, while a fourth section (207) is attached to the third section (205) having a narrowly spaced pitch. The antenna further includes a parasitic element (213a/213b) that is positioned adjacent to each of the first section (201), second section (203), third section (205), and fourth section (207) for enhancing broad-band antenna performance. A matching network (216) is connected between an antenna feed point and the first section (201) for matching the dual band multi-pitch helical antenna to a predetermined feed point impedance such that the antenna is resonant in at least two frequency bands.

Abstract: A system for protecting against unplanned state changes of a magnetic latching relay (100) includes logic switching logic circuits (101, 105) for controlling a driver circuit (103) that works to supply a drive voltage to a magnetic latching relay (109). The switching logic circuits (101, 105) work to detect any unplanned state changes that may occur due to vibration or the like of the magnetic latching relay (109). The invention acts to switch the magnetic latching relay (109) back to a desired state after this state change has been detected in a two-way radio transceiver or other electronic device.