초록 ▼

Physically small quadrifilar helix antenna systems capable of providing a positive gain, quasi-hemispherical antenna pattern over a relatively broadband frequency range in the L-Band frequency band. The antenna systems according to the present invention generally comprise a quadrifilar helix antenna

Physically small quadrifilar helix antenna systems capable of providing a positive gain, quasi-hemispherical antenna pattern over a relatively broadband frequency range in the L-Band frequency band. The antenna systems according to the present invention generally comprise a quadrifilar helix antenna and at least one antenna feed network, and may further comprise matching means for improving the broadband frequency performance of the antenna. In a preferred embodiment, the elements of the quadrifilar helix antenna which form each bifilar helix are short-circuited at their distal ends, and energy is fed to and induced from the antenna via receive and transmit 90.degree. hybrid couplers which are electrically connected to the bifilar loops of the quadrifilar helix antenna. The antenna systems may further include first and second circuit branches for changing the resonant frequency of the antenna to first and second resonant frequencies corresponding to separate transmit and receive frequency bands, and switches or other disconnection means which are used to electrically isolate the first circuit branch from the antenna during periods when the antenna is receiving a signal and to electrically isolate the second circuit branch from the antenna during periods of transmission.

대표청구항 ▼

[ That which is claimed is:] [5.] An antenna system for a handheld transceiver for transmitting and receiving radio frequency signals in the L-Band frequency band comprising:(a) a quadrifilar helix antenna having four antenna elements, wherein an axial length of each element is between 7 and 9 centi

[ That which is claimed is:] [5.] An antenna system for a handheld transceiver for transmitting and receiving radio frequency signals in the L-Band frequency band comprising:(a) a quadrifilar helix antenna having four antenna elements, wherein an axial length of each element is between 7 and 9 centimeters and a diameter of a cylinder defined by said antenna is between 6 and 13 millimeters, wherein said antenna elements each have an origin and a distal end, and wherein the origin of said first and third antenna elements are coupled to said transceiver, and the origin of said second and fourth antenna elements are coupled to a first reference voltage, and wherein said first and second antenna elements are electrically connected at their distal ends and said third and fourth antenna elements are electrically connected at their distal ends; and(b) means for coupling signals between said quadrifilar helix antenna and said transceiver.