Thick folded dipole which is tuneable within a frequency band of two octaves

• US 4,005,430 A
• Filed: 01/12/1976
• Issued: 01/25/1977
• Est. Priority Date: 01/17/1975
• Status: Expired due to Term

• Current Assignee: Etat Francais Represente Par Le Delegue Ministeriel Pour L'Armement
• Original Assignee: Etat Francais Represente Par Le Delegue Ministeriel Pour L'Armement
• Inventors: Dubost, Gerard, Havot, Henri Albert
• Primary Examiner(s): Lieberman, Eli
• Application Number:
  US05/648,290
• Time in Patent Office: 379 Days
• Field of Search: 343/745, 343/747, 343/752, 343/803, 343/804, 343/807, 343/845
• US Class Current: 343/747
• CPC Class Codes: H01Q 9/26 with folded element or elements, the folded parts being spaced apart a small fraction of operating wavelength resonant loop antennas H01Q7/00

Abstract

A thick folded dipole having an operating frequency which is far less thanhe first resonance frequency. The dipole includes a folded strand and a thick fed strand having a diameter which is about ten times greater than the diameter of the folded strand. The fed strand comprises two spaced apart cylindrical half strands having ends in the form of conical frustums and coaxial bore holes. A center conductor of a coaxial cable extends through the folded strand, the bore hole of one half strand, the space between the half strands and into the bore hole of the other half strand. Symmetrical spaced apart short circuits for matching the radiation impedance of the dipole by varying the distance between the short circuits are provided between the fed strand and the folded strand. In another embodiment there is disclosed a thick folded half dipole including a folded half strand and a thick fed cylindrical half strand.

Claims

1. A thick folded dipole, comprising:

a. a folded strand having a bore hole;

b. a thick fed strand having a diameter which is about ten times greater than the diameter of said folded strand;

said fed strand including two spaced apart symmetrical cylindrical half strands having ends in the form of conical frustums and coaxial bore holes;

c. a coaxial cable for carrying signals to be emitted or received by the dipole, said cable including a center conductor extending through the bore hole of said folded strand, the bore hole of one half strand, the space between said half strands and into the bore hole of the other half strand; and

d. symmetrical spaced apart short circuit means for matching the radiation impedance of the dipole by varying the distance between said short circuit means, said means being provided between said fed strand and said folded strand, wherein the operating frequency of the dipole is far less than the first resonance frequency.

2. A thick folded dipole according to claim 1 wherein said other half strand has connected inside of it a fixed capacitance and the end of said center conductor within said other half strand is connected to said other half strand by said fixed capacitance.

3. A thick folded dipole according to claim 1 wherein said other half strand has connected inside of it a variable capacitance, and the end of said center conductor within said other half strand is connected to said other half strand by said variable capacitance.

4. A thick folded dipole according to claim 3 wherein said variable capacitance includes a dielectric sleeve positioned to a greater or lesser extent over said end of said center conductor.

5. A thick folded dipole according to claim 1 wherein said other half strand has connected inside of it a variable inductance, and the end of said center conductor within said other half strand is connected to said other half strand by said inductance.

6. A thick folded dipole according to claim 1 wherein said other half strand has inside of it a switch means having a movable contact and connected to the end of said center conductor within said other half strand, a variable inductance connected to said other half strand, and a variable capacitance connected to said other half strand, said contact being movable to contact either said inductance or said capacitance, whereby said end of said conductor is connected to said other half strand either by said inductance or said capacitance.

7. A thick folded half dipole, comprising:

a. a folded half strand having a first bore hole;

b. a thick fed cylindrical half strand having a diameter which is about ten times greater than the diameter of said folded strand, said cylindrical half strand having an end in the form of a conical frustum and a second bore hole;

c. a ground conductive metallic plate having a flat surface perpendicular to the longitudinal axis of the half dipole, said plate forming a reflector plane and having a third hole;

d. a capacitance within the third hole and connected to said plate;

e. an inductance within the third hole and connected to said plate;

f. a switch means within the third hole and having a movable contact for connection either to said capacitance or said inductance;

g. short circuit means provided between said folded half strand and said cylindrical half strand for matching the radiation impedance of the half dipole by varying the distance between said short circuit means and an end of said cylindrical half strand; and

h. a coaxial cable for carrying signals to be emitted or received by the half dipole, said cable including a center conductor extending through the bore holes of said folded half strand and said cylindrical half strand and connected to said switch means, whereby said center conductor is connected to said plate either by said capacitance or said inductance.

8. A thick folded half dipole according to claim 7 wherein said capacitance is variable.

9. A thick folded half dipole according to claim 7 wherein said inductance is variable.