Foreshortened dipole antenna with triangular radiating elements and tapered coaxial feedline

A foreshortened log-periodic antenna

• a first region comprising a series of solid triangular dipole elements characterized by a substantially constant base-to-height ratio;
• a second, transition, region comprising a series of triangular dipole elements characterized by a gradually decreasing base-to-height ratio;
• a third region comprising at least one linear dipole element;
• and
• a coaxial feedline including a first coaxial portion and a second coaxial portion along which the second coaxial portions are juxtapositioned so as to dipole elements are positioned, wherein the first and exhibit an axial separation that increases in the direction away from the first region so that the characteristic impedance of the feedline concomitantly increases along that direction.

A log-periodic dipole antenna comprising:

• a coaxial feedline that includes a first, substantially linear, coaxial portion and includes a second, substantially linear, coaxial portion, said first and said second coaxial portions juxtapositioned so that the portions are separated by a distance "d" at a first end of the feedline and are separated by a distance greater than "d" at a second end of the feedline, with the result that the feedline presents a characteristic impedance that increases along the length of the feedline in the direction from the first end of the feedline toward the second end of the feedline;
• and
• a first plurality of dipoles disposed at the first end of the feedline, said first plurality of dipoles of solid triangular construction and characterized by substantially constant base-to-height ratios;
• a second plurality of dipoles disposed between the first plurality of dipoles and the second end of the feedline, said second plurality of dipoles of solid triangular construction and characterized by decreasing base-to-height ratios;
• and
• a linear dipole disposed between the second plurality of dipoles and the second end.

A log-periodic antenna comprising two complementary sections, a bottom section and a top section, wherein the top section includes a top coaxial portion (200) along which are disposed a plurality of top dipole elements (210), (211), (212), (213), (214), (215), (216), (217), (218), and (219) and wherein the bottom section includes a bottom coaxial portion (100) along which are disposed a plurality of bottom dipole elements (110), (111), (112), (113), (114), (115), (116), (117), (118), and (119), said top coaxial portion and said bottom coaxial portion juxtapositioned so as to exhibit an axial separation that increases along the lengths of coaxial portions (110) and (200) in the direction extending from elements (110) and (210) to elements (119) and (219) so that the characteristic impedance of a feedline formed by coaxial portions (100) and (200) increases along the length of the antenna in the above-defined direction and wherein said elements (110) through (119) and (210) through (219) are disposed along the lengths of coaxial portions (100) and (200) so as to form;

• (1) a first region consisting of elements (110), (210), (11), (211), (112) and (212), said elements (110), (210), (110), (211), (112), and (212) together forming a series of solid triangular dipoles characterized by substantially constant base-to-height ratios, (2) a second region, consisting of elements (113), (213), (114), (214), (115) and (215), said elements (113), (213), (114), (214), (115), and (215) together forming a series of solid triangular dipoles characterized by decreasing base-to-height ratios, (3) a third region, consisting of elements (116) and (216), which together form a linear dipole, and (4) a fourth region, consisting of elements (117), (217), (118), (218), (119), (and 219), said elements (117), (217), (118), (218), (119) and (219) together forming a series of foreshortened dipoles.