Patent ID: 6160516
Filing Date: 2000-12-12
Classification: H01Q

Abstract:
In a communications device, a method for modifying a radiation pattern of an antenna which receives communication signals, comprising the steps of:coupling first and second feed elements to a proximal end portion of a quadrifilar helical antenna;moving said first and second feed elements from said proximal end portion to a distal end portion of said quadrifilar helical antenna;said moving step comprises the step of changing a capacitance from a first value to a second value, said first value being between said first and second feed elements and said first and second pairs of conductive helical strips located at said distal end portion of said quadrifilar helical antenna, and said second value being between said first and second feed elements and said first and second pairs of conductive helical strips located at said proximal end portion of said quadrifilar helical antenna;said moving step further comprises the step of changing a distance from a first value between said first and second feed elements and said first and second pairs of conductive helical strips to a second value between said first and second feed elements and said first and second pairs of conductive helical strips; andcoupling said first and second feed elements to a first pair of conductive helical strips at said proximal end portion of said quadrifilar helical antenna and coupling said second feed element to a second pair of conductive helical strips of said quadrifilar helical antenna to form a bi-filar helical antenna.