Backfire bifilar helix antenna

Claim 2

A backfire bifilar helix antenna having a pair of opposing spiral conductors for radiating or receiving a circularly polarized wave, comprising: first and second coaxial cables helically wound in excess of one full turn in the same direction and having a predetermined radius and constant pitch, said coaxial cables having a center conductor and a shield conductor, the shield conductors of said cables forming said pair of opposing spiral conductors; infinite balun feed means for coupling signals of equal magnitude and 180° out of phase to one end of said first and second coaxial cables, said feed means including a transmission line comprising the center conductor and the shield conductor of one of said coaxial cables, and wherein said center conductor of said transmission line is directly connected to the shield conductor of the other coaxial cable at said one end; and means for adjusting the input impedance of the antenna to a predetermined value, said least mentioned means including identical tuned conductive surface layers directly connected to the shield conductors of said first and second coaxial cables at said one end.

Claim 3

The backfire bifilar helix antenna of claim 1, wherein said first and second coaxial cables are wound on a tubular member.

Claim 4

The backfire bifilar helix antenna of claim 2, further including a disk made of insulative material attached to an end of said tubular member, said conductive surface layers being disposed on said data.

Claim 5

The backfire bifilar helix antenna of claim 1, wherein said signals of equal magnitude and 180° out of phase induce a traveling wave which is attenuated in a direction along said first and second coaxial cables away from said one end.

Claim 6

The backfire bifilar helix antenna of claim 4, wherein said first and second conductors are connected together at a second end, thereby preventing remnants of said traveling wave from continuing along said transmission line.

Claim 7

The backfire bifilar helix antenna of claim 1, wherein said opposing spiral conductors have a spiral length of approximately three full turns.

Claim 8

The backfire bifilar helix antenna of claim 1, wherein said identical tuned conductive surface layers are formed from larger surface layer configurations which have been trimmed in size and moved with respect to the shield conductors of said first and second coaxial cables in order to obtain the desired impedance match for the antenna.

Claim 9

A backfire bifilar helix antenna having a pair of opposing spiral conductors for radiating or receiving a circularly polarized wave, comprising: first and second coaxial cables helically wound approximately three full turns in the same direction and having a predetermined radius and constant pitch, said coaxial cables having a center conductor and a shield conductor, the shield conductors of said cables forming said pair of opposing spiral conductors; infinite balun feed means for coupling signals of equal magnitude and 180° out of phase to one end of said first and second coaxial cables, said feed means including a transmission line comprising the center conductor and the shield conductor of one of said coaxial cables, and wherein said center conductor of said transmission line is directly connected to the shield conductor of the other coaxial cable at said one end so as to induce a traveling wave which is attenuated to a low level in a direction away from said one end; and means for adjusting the input impedance of the antenna to a predetermined value, said last mentioned means including identical tuned conductive surface layers directly connected to the shield conductors of said first and second coaxial cables at said one end, wherein said identical tuned conductive surface layers are formed from larger surface layer configurations which have been trimmed in size and moved with respect to the shield conductors of said first and second coaxial cables in order to obtain the desired impedance match for the antenna.

Claim 10

A backfire bifilar helix antenna having a pair of opposing spiral conductors for radiating or receiving a circularly polarized wave, comprising: first and second coaxial cables helically wound approximately three full turns in the same direction and having a predetermined radius and constant pitch, said coaxial cables having a center conductor and a shield conductor, the shield conductors of said cables forming said pair of opposing spiral conductors; infinite balun feed means for coupling signals of equal magnitude and 180° out of phase to one end of said first and second coaxial cables, said feed means including a transmission line comprising the center conductor and the shield conductor of one of said coaxial cables, and wherein said center conductor of said transmission line is directly connected to the shield conductor of the other coaxial cable at said one end so as to induce a traveling wave which is attenuated to a low level in a direction away from said one end; and means for adjusting the input impedance of the antenna to a predetermined value, said last mentioned means including identical tuned conductive surface layers directly connected to the shield conductors of said first and second coaxial cables at said one end, wherein said identical tuned conductive surface layers are formed from larger surface layer configurations which have been trimmed in size and moved with respect to the shield conductors of said first and second coaxial cables in order to obtain the desired impedance match for the antenna.