Switchable length whip antenna
AssigneeBAE Systems Information and Electronic Systems Integration Inc.
InventorsAlfred R. Lopez, John F. Pedersen, Joseph T. Merenda
Life of this patent
Estimating the term…
Abstract
A whip antenna with switchable operative length provides seven band coverage from 30 to 90 MHZ. A coaxial choke section below a fixed upper antenna element is used for the highest frequency band. A series of four coaxial line sections are switchably coupled below the choke section to increase its operative length for operation in bands of successively lower frequency. One or more lumped constant non-coaxial transmission line sections are switchably coupled below the coaxial line sections for operation in the two lowest frequency bands. Dipole level gain is provided with low reflections loss. Increased height gain is provided by height of operative antenna elements employed at higher frequency bands.
Claims27
A whip antenna, with switchable operative length for multi-band operation, comprising:
- an upper antenna element having a vertical axis;
- a choke section coaxial to said vertical axis below the upper antenna element;
- at least one coaxial line section along said vertical axis below and spaced from the choke section;
- at least one transmission line section non-coaxial to said vertical axis in spaced relation below the at least one coaxial line section;
- a plurality of switch devices arranged to selectively couple the coaxial line and transmission line sections in series with the choke section;
- and
- a driver configuration coupled to the switch devices to selectively activate the switch devices to change the operative length of the antenna to enable operation in a plurality of frequency bands.
A whip antenna, with switchable operative length for multi-band operation, comprising:
- an upper antenna element having a vertical axis;
- a choke section coaxial to said vertical axis below the upper antenna element;
- a first coaxial line section along said vertical axis below and isolated from the choke section;
- a second coaxial line section along said vertical axis below and isolated from the first coaxial line section;
- a first switch device arranged to selectively couple the first coaxial line section to the choke section;
- a second switch device arranged to selectively couple the second coaxial line section to the first coaxial line section;
- and
- a driver configuration coupled to the switch devices to enable selective activation thereof to change the operative length of the antenna.
A whip antenna, with switchable operative length for multi-band operation, comprising:
- an upper antenna element having a vertical axis;
- a choke section coaxial to said vertical axis below the upper antenna element, the combination of the upper antenna element and choke section operable as a dipole antenna in an upper frequency band;
- a first coaxial line section along said vertical axis below and isolated from the choke section, the combination of the upper antenna element with the choke and coaxial line sections operable as a dipole antenna in a lower frequency band;
- a switch device arranged to selectively couple the first coaxial line section to the choke section;
- and
- a driver configuration coupled to the switch device to selectively activate the switch device to couple the first coaxial line section to the choke section for operation in the lower frequency band.
A whip antenna, with switchable operative length for multi-band operation, comprising:
- an upper antenna element having a vertical axis;
- a coaxial cable section along said vertical axis and including an inner conductor coupled to the upper antenna element and an outer conductor;
- a choke section below the upper antenna element and including a cylindrical portion encircling part of the cable section, the choke section coupled to said outer conductor;
- first, second, third and fourth coaxial line sections respectively positioned below the choke section at successively lower positions and each including a cylindrical portion encircling part of the cable section;
- and
- a plurality of switch devices arranged to selectively couple to the choke section one of (a) the first coaxial line section, (b) the first and second coaxial line sections, (c) the first, second and third coaxial line sections, and (d) the first second, third and fourth coaxial line sections.
A whip antenna, with switchable operative length for multi-band operation, comprising:
- an upper antenna element having a vertical axis;
- a coaxial cable section along said vertical axis and including an inner conductor coupled to the upper antenna element and an outer conductor;
- a choke section below the upper antenna element and including a cylindrical portion encircling part of the cable section, the choke section coupled to said outer conductor;
- first, second, third and fourth coaxial line sections respectively positioned below the choke section at successively lower positions and each including a cylindrical portion encircling part of the cable section;
- and
- a plurality of switch devices arranged to selectively couple to the choke section one of (a) the first coaxial line section, (b) the first and second coaxial line sections, (c) the first, second and third coaxial line sections, and (d) the first second, third and fourth coaxial line sections;
- wherein components of the antenna have nominal vertical dimensions as follows:
- upper antenna element, 1.30 meters;
- choke section, 0.60 meters;
- first coaxial line section, 0.52 meters;
- second coaxial line section, 0.36 meters;
- third coaxial line section, 0.13 meters;
- and
- fourth coaxial line section, 0.08 meters.
Dependencies are inferred from the claim text.