Vertically polarized log-periodic-like antenna with minimal tower height

Claim 2

An antenna, designed for operation over a selected frequency band including a first frequency and a second frequency, lower than said first frequency, comprising: a plurality of radiating elements, the equivalent electrical length of each element being a function of the wavelength of signals of a different frequency in said frequency band; support means for supporting said elements in a selected orientation with respect to a reference surface to form an array of elements wherein the elements are arranged in an order corresponding to their equivalent electrical lengths, with the element whose equivalent electrical length is a function of the wavelength of signals of said first frequency being at a front end of said array, and the element whose electrical equivalent length is a function of the wavelength of signals of said second frequency being at a back end of said array, said array including at least a first element whose physical length is equal to its equivalent electrical length and at least a second element whose physical length is less than its equivalent electrical length, said second element including impedance loading means for compensating for the difference between its physical length and its equivalent electrical length, the elements being supported in spaced relationship from one another to inhibit the coupling of energy therebetween; and feed means electrically coupled to said elements, said feed means being coupled to said first element at the physical center thereof and to said second element at other than the physical center thereof.

Claim 3

The arrangement as recited in claim 1 wherein said feed means further include means coupled to said support means to mechanically coact therewith in supporting said array of elements in said selected orientation with respect to said reference surface, with said feed means acting as a load-bearing member.

Claim 4

The arrangement as recited in claim 1 wherein said reference surface is the ground and said selected orientation is a vertical plane with respect to ground, and said impedance loading means comprise capacitive means for capacitively coupling said second element to ground.

Claim 5

The arrangement as recited in claim 2 wherein said support means include a main support catenary extending from said array back end to the front end thereof, said catenary having at least one electrically conductive segment, electrical insulating means for connecting selected ones of said elements, at and near the array front end, to said catenary in electrical insulation therefrom, and means for connecting at least one element, located toward the array back end, to said catenary to be in electrical contact with said at least one electrically conductive segment thereof.

Claim 6

The arrangement as recited in claim 1 wherein said selected orientation is a vertical plane above said reference surface, with said elements forming a vertically polarizEd log-periodiclike array of elements, defining an apex above said reference surface about the array front end, each element having at least a portion thereof parallel to corresponding portions of the other elements, and said support means include a main support catenary for directly supporting the top ends of substantially all the elements at and about the array back end in said vertical plane with said feed means further serving as a secondary support catenary to thereby reduce the maximum height of said main support catenary.

Claim 7

The arrangement as recited in claim 5 wherein said main support catenary includes at least one electrically conductive segment and said array includes at least one element electrically connected at its top end to said electrically conductive segment of said main support catenary.

Claim 8

A vertically polarized log-periodiclike antenna, designed to operate over a frequency band including a first frequency and a second frequency, lower than said first frequency, the antenna comprising: a plurality of dipoles, each having an equivalent electrical length which is a function of one-half the wavelength of the signals of a different frequency in said band at which the dipole is designed to resonate, said dipoles including a first group of dipoles each dipole in said first group having a physical length which is equal to its equivalent electrical length and a second group of dipoles, each dipole in said second group having a physical length which is less than the dipole''s equivalent electrical length, said dipoles being arranged to form a log-periodiclike array with the dipole having the shortest equivalent electrical length being disposed at the array front end and the dipole having the longest equivalent electrical length being disposed at the array back end, with the dipoles in said first group being disposed toward the array front end and the dipoles in said second group being disposed toward the array back end; feed line means; means for electrically coupling said dipoles to said feed line means at points on said feed line means which are related distances from an apex of said array, each dipole in said first group being coupled to said feed line means at the physical center of said dipole and each dipole in said second group being coupled to said feed line means at other than the dipole''s physical center; and antenna support means for supporting said dipoles in a vertical plane above a reference surface, said support means including a main support tower of a height which is less than one-half the wavelength of the signals of a frequency at which the longest dipole is designed to resonate.

Claim 9

A vertically polarized log-periodiclike antenna, designed to operate over a frequency band including a first frequency and a second frequency, lower than said first frequency, the antenna comprising: a plurality of dipoles, each having an equivalent electrical length which is a function of one-half the wavelength of the signals of a different frequency in said band at which the dipole is designed to resonate, said dipoles including a first group of dipoles each dipole in said first group having a physical length which is equal to its equivalent electrical length and a second group of dipoles, each dipole in said second group having a physical length which is less than the dipole''s equivalent electrical length, said dipoles being arranged to form a log-periodiclike array with the dipole having the shortest equivalent electrical length being disposed at the array front end and the dipole having the longest equivalent electrical length being disposed at the array back end, with the dipoles in said first group being disposed toward the array front end and the dipoles in said second group being disposed toward the array back end; feed line means; means for electrically coupling said dipoles to said feed line means at points on said feed line means which are related distances from an apex of said array, each dipole in said first group being coupled to said feed line means at the physical center of said dipole and each dipole in said second group being coupled to said feed line means at other than the dipole''s physical center; and antenna support means for supporting said dipoles in a vertical plane above a reference surface, said support means including a main support tower of a height which is less than one-half the wavelength of the signals of a frequency at which the longest dipole is designed to resonate.

Claim 10

A vertically polarized log-periodiclike antenna as described in claim 7 wherein each dipole in said second group includes loading means for loading the dipole to compensate for the difference between its physical and equivalent electrical lengths.

Claim 11

A vertically polarized log-periodiclike antenna as described in claim 8 wherein each dipole comprises first and second poles, said support means including means for supporting each first pole above said feed line means and each second pole below said feed line means, each dipole in said second group having at least one pole with a physical length less than one-half the dipole''s equivalent electrical length, said loading means including means coupled to said at least one pole of each dipole in said second group.

Claim 12

A vertically polarized log-periodiclike antenna as described in claim 9 wherein said at least one pole of each dipole in said second group is the second pole below said feedline means.

Claim 13

A vertically polarized log-periodiclike antenna as described in claim 10 wherein each of the poles of the dipole, having the longest equivalent electrical length, has a physical length which is less than one-half of the dipole''s equivalent electrical length, said loading means including capacitive means for loading the second pole of the longest dipole and cable-loading meAns extending from the first pole of said longest dipole for loading said first pole to compensate for the difference between its actual physical length and one-half the equivalent electrical length of the longest dipole.

Claim 14

A vertically polarized log-periodiclike antenna as described in claim 11 wherein said antenna support means includes a main support catenary having at least one electrically conductive segment comprising said cable loading means.

Claim 15

A vertically polarized log-periodiclike antenna as described in claim 7 wherein the equivalent electrical lengths of the dipoles in said first group are related by sigma 1 where Ln being the equivalent electrical length of any dipole in said first group excluding the longest dipole and Ln 1 is the next longer dipole, and the equivalent electrical length of at least some of the dipoles in said second group are related by sigma 2 where Lm being the equivalent electrical length of any dipole in said second group excluding the longest dipole and Lm is the next longer dipole.

Claim 16

A broadband dipole-type vertically polarized log-periodiclike antenna for providing the high electrical gain at the upper frequencies in said band, characteristic of a dipole type vertically polarized log-periodic antenna, the antenna comprising: a log-periodiclike array having a front end and a back end; and array support means for supporting said array in a vertically polarized plane above an electrically conductive surface, said array including a feedline and a plurality of dipoles coupled thereto, each dipole comprising a top pole above said feed line and a bottom pole below said feed line, the dipoles including a first group of dipoles near the front end of said array, each dipole in said first group having a physical length substantially equal to its equivalent electrical length which is substantially one-half of the wavelength of signals at a frequency at which said dipole is to radiate most strongly, said dipoles including a second group of dipoles each having a physical length which is less than its equivalent electrical length which equals one-half the wavelength of the signals of a frequency at which the dipole is to radiate most strongly, with the bottom pole of each dipole in said second group having a physical length which is less than one-half of the dipole''s equivalent electrical length, and bottom loading means coupled to the bottom pole of each dipole in said second group to the compensate electrically for the difference between the physical length of the bottom pole and one-half the equivalent electrical length of the dipole.

Claim 17

A broadband dipole-type vertically polarized log-periodiclike antenna for providing the high electrical gain at the upper frequencies in said band, characteristic of a dipole type vertically polarized log-periodic antenna, the antenna comprising: a log-periodiclike array having a front end and a back end; and array support means for supporting said array in a vertically polarized plane above an electrically conductive surface, said array including a feedline and a plurality of dipoles coupled thereto, each dipole comprising a top pole above said feed line and a bottom pole below said feed line, the dipoles including a first group of dipoles near the front end of said array, each dipole in said first group having a physical length substantially equal to its equivalent electrical length which is substantially one-half of the wavelength of signals at a frequency at which said dipole is to radiate most strongly, said dipoles including a second group of dipoles each having a physical length which is less than its equivalent electrical length which equals one-half the wavelength of the signals of a frequency at which the dipole is to radiate most strongly, with the bottom pole of each dipole in said second group having a physical length which is less than one-half of the dipole''s equivalent electrical length, and bottom loading means coupled to the bottom pole of each dipole in said second group to the compensate electrically for the difference between the physical length of the bottom pole and one-half the equivalent electrical length of the dipole.

Claim 18

A broadband dipole-type vertically polarized log-periodiclike antenna as described in claim 14 wherein said array support means including a tower of height less than the equivalent electrical length of the longest dipole in said array.

Claim 19

A broadband dipole-type vertically polarized log-periodiclike antenna as described in claim 15 wherein said second group of dipoles includes first and second subgroups, the physical length of the top pole of each dipole in said first subgroup being substantially equal to one-half the dipole''s equivalent electrical length, and the physical length of the top pole of each dipole in said second subgroup being less than one-half of the dipole''s equivalent electrical length, and cable loading means electrically coupled to the top poles of the dipoles in said second subgroup for compensating for the differences between their physical lengths and one-half of their dipole''s equivalent electrical lengths.

Claim 20

A broadband dipole-type vertically polarized log-periodiclike antenna as described in claim 14 wherein the equivalent electrical lengths of the dipoles in said first group are related by sigma 1, where Ln being the equivalent electrical length of any dipole in said first group Excluding the longest dipole in the group and Ln 1 is the equivalent electrical length of the adjacent longer dipole, and at least some of the dipoles in said second group have equivalent electrical lengths which are related by sigma 2 Lm being the equivalent electrical length of any dipole in said second group, excluding the longest dipole in the group, and Lm 1 is the equivalent electrical length of the adjacent longer dipole.

Claim 21

A broadband dipole-type vertically polarized log-periodiclike antenna as described in claim 17 wherein said cable loading means comprise a plurality of electrically conductive cables extending from the top end of substantially every pole in said second subgroup to said main support catenary.

Claim 22

A broadband dipole-type vertically polarized log-periodiclike antenna as described in claim 17 wherein said bottom loading means comprise a plurality of capacitors each coupled between the bottom end of a different bottom pole of a dipole in said second group and said conductive surface, said array support means include a main support catenary having electrically conductive segments insulated from one another, said electrically conductive segments comprising said cable loading means.

Claim 23

A broadband dipole-type vertically polarized log-periodiclike antenna as described in claim 19 wherein the top end of each top pole of each dipole in said second group is directly mechanically or electrically coupled to said catenary.

Claim 24

A broadband dipole-type vertically polarized log-periodiclike antenna as described in claim 16 wherein said bottom loading means comprise a plurality of capacitors each coupled between the bottom end of a different bottom pole of a dipole in said second group and said conductive surface, said array support means include a main support catenary having electrically conductive segments insulated from one another, said electrically conductive segments comprising said cable loading means.

Claim 25

A broadband dipole-type vertically polarized log-periodiclike antenna as described in claim 21 wherein the top end of each top pole of each dipole in said second group is directly mechanically or electrically coupled to said catenary.