Critically coupled bi-periodic driver antenna

• US 5,841,406 A
• Filed: 08/19/1996
• Issued: 11/24/1998
• Est. Priority Date: 08/19/1996
• Status: Expired due to Fees

• Current Assignee: Sidney C. Smith
• Original Assignee: Sidney C. Smith
• Inventors: Smith, Sidney C.
• Primary Examiner(s): Le, Hoanganh T.
• Assistant Examiner(s): Ho, Tan
• Application Number:
  US08/697,033
• Time in Patent Office: 827 Days
• Field of Search: 343/810, 343/812, 343/815, 343/818, 343/833, 343/819, 343/890, 343/778, 343/793
• US Class Current: 343/815
• CPC Class Codes: H01Q 1/1228 on a boom
• CPC Class Codes: H01Q 19/30 the primary active element being centre-fed and substantially straight, e.g. Yagi antenna

Abstract

The present invention is an improved Yagi-Uda style antenna. Primarily, the present invention provides that at least two driven elements are spaced approximately 0.1 λ apart from each other. The driven elements are forced into a critical couple mode by electrically connecting the two driven elements with a matched phasing delay line. The phasing delay line retards the phase current sufficiently to, coupled with the specified element separation, satisfy both the endfire condition and the Hansen-Woodyard condition. This provides for increased directivity and gain, and deep nulls in the field strength. The at least two critically coupled elements compromise at least a first driven element, which is the primary broadcast element, and a second driven element, which is a driven reflector element. The reflector element acts to augment field strength in a direction toward the first driven element and reduce field strength in a direction away from the first driven element. The present invention may include the use of at least one parasitic director elements. These are elements that are not electrically coupled to the driven elements, but are inductively coupled. The present invention further provides an antenna with a greatly reduced loss resistance component. The present invention reduces nonradiative resistance losses with an element mounting saddle that incorporates an enlarged conductive contact surface area. This enlarged conductive contact surface area is designed to conform with the surface of the radiative element to be mounted on the saddle. By increasing the conductive contact surface area, current density at any one point in the contact is reduced. This allows larger currents to flow through the contact area with less resistance heating.

Claims

1. An antenna comprising:

i) a mast;

ii) a boom assembly;

iii) a boom-to-mast mounting bracket for attaching the boom assembly to the mast;

iv) first and second driven element assemblies, said first driven element assembly having a length approximately one half of the operating frequency wavelength of the antenna, and said second driven element assembly having a length greater than one half of the operating frequency wavelength of the antenna and the distance between the first and second driven element assemblies is approximately 0.1 of the operating frequency wavelength of the antenna;

v) two element drivers, one for each element assembly, for electrically driving the element assembly, said element driver having a matching arm with an aperture at a first end, a stand-off insulator attached at one end to the element assembly and at an opposite end to the first end of the matching arm, and a shorting strap attached at one end to the element assembly and at an opposite end to a second end of the matching arm;

vi) first and second driven element saddle brackets, the first and second driven element saddle brackets attaching the first and second driven element assemblies to the boom assembly respectively, wherein the first driven element saddle bracket has an element attachment portion with an enlarged contact surface area contoured to closely fit the first element assembly, a boom mounting portion attached to the element attachment portion, and a RP connector attachment portion connected to the boom mounting portion, the second driven element saddle bracket has an element attachment portion with an enlarged contact surface area contoured to closely fit the second element assembly, and a boom mounting portion attached to the element attachment portion; and

vii) an electrical circuit comprising a radio frequency transmitter/receiver, a coaxial cable connected at one end to the radio frequency transmitter/receiver and connected at an opposite end to the RF connector which is attached to the RF connector attachment portion of the first driven element saddle bracket, a 0.66 velocity factor phasing delay line with at least a first conductor and a second conductor, said first conductor attached at one end to a center post on the RF connector and jumpered to the element driver on the first drive n element assembly and attached at an opposite end to the element driver on the second driven element assembly, and said second conductor attached at one end to a first driven element saddle bracket and attached at an opposite end to a second driven element saddle bracket.

2. An antenna comprising:

i) a mast;

ii) a boom assembly;

iii) a boom-to-mast mounting bracket for attaching the boom assembly to the mast;

iv) first and second driven element assemblies, said first driven element assembly having a length approximately one half of the operating frequency wavelength of the antenna, and said second driven element assembly having a length greater than one half of the operating frequency wavelength of the antenna and the distance between the first and second driven element assemblies is approximately 0.1 of the operating frequency wavelength of the antenna;

v) a parasitic director element assembly having a length less that one half of the operating frequency wavelength of the antenna, and being separated from the first driven element assembly by between 0.25 and 0.33 of the operating frequency wavelength of the antenna;

vi) two element drivers, one for each driven element assembly, for electrically driving the element assembly, said element driver having a matching arm with an aperture at a first end, a stand-off insulator attached at one end to the element assembly and at an opposite end to the first end of the matching arm, and a shorting strap attached at one end to the element assembly and at an opposite end to a second end of the matching arm;

vii) first and two second driven element saddle brackets, the first driven element saddle bracket attaching the first driven element assembly to the boom assembly and two second driven element saddle brackets attaching the second driven element assembly and parasitic element assembly to the boom assembly, wherein the first driven element saddle bracket has an element attachment portion with an enlarged contact surface area contoured to closely fit the first element assembly, a boom mounting portion attached to the element attachment portion, and a RF connector attachment portion connected to the boom mounting portion, the second driven element saddle bracket has an element attachment portion with an enlarged contact surface area contoured to closely fit the second element assembly, and a boom mounting portion attached to the element attachment portion; and

viii) an electrical circuit comprising a radio frequency transmitter/receiver, a coaxial cable connected at one end to the radio frequency transmitter/receiver and connected at an opposite end to the RF connector which is attached to the RF connector attachment portion of the first driven element saddle bracket, a 0.76 velocity factor phasing delay line with at least a first conductor and a second conductor, said first conductor attached at one end to a center post on the RF connector and jumpered to the element driver on the first driven element assembly and attached at an opposite end to the element driver on the second driven element assembly, and said second conductor attached at one end to a first driven element saddle bracket and attached at an opposite end to a second driven element saddle bracket.

3. An antenna comprising:

i) a mast;

ii) a boom assembly;

iii) a boom-to-mast mounting bracket for attaching the boom assembly to the mast;

iv) first and second driven element assemblies, said first driven element assembly having a length approximately one half of the operating frequency wavelength of the antenna, and said second driven element assembly having a length greater than one half of the operating frequency wavelength of the antenna and the distance between the first and second driven element assemblies is approximately 0.1 of the operating frequency wavelength of the antenna;

v) two parasitic director element assemblies, each having a length less that one half of the operating frequency wavelength of the antenna, and a first parasitic element assembly being separated from the first driven element assembly by between 0.25 and 0.33 of the operating frequency wavelength of the antenna and a second parasitic element assembly being separated from the first parasitic element assembly by between 0.25 and 0.33 of the operating frequency wavelength of the antenna;

vi) two element drivers, one for each driven element assembly, for electrically driving the element assembly, said element driver having a matching arm with an aperture at a first end, a stand-off insulator attached at one end to the element assembly and at an opposite end to the first end of the matching arm, and a shorting strap attached at one end to the element assembly and at an opposite end to a second end of the matching arm;

vii) first and three second driven element saddle brackets, the first driven element saddle bracket attaching the first driven element assembly to the boom assembly and the three second driven element saddle brackets attaching the second driven element assembly and two parasitic element assembly to the boom assembly, wherein the first driven element saddle bracket has an element attachment portion with an enlarged contact surface area contoured to closely fit the first element assembly, a boom mounting portion attached to the element attachment portion, and a RF connector attachment portion connected to the boom mounting portion, the second driven element saddle bracket has an element attachment portion with an enlarged contact surface area contoured to closely fit the second element assembly, and a boom mounting portion attached to the element attachment portion; and

viii) an electrical circuit comprising a radio frequency transmitter/receiver, a coaxial cable connected at one end to the radio frequency transmitter/receiver and connected at an opposite end to the RF connector which is attached to the RF connector attachment portion of the first driven element saddle bracket, a 0.76 velocity factor phasing delay line with at least a first conductor and a second conductor, said first conductor attached at one end to a center post on the RF connector and jumpered to the element driver on the first driven element assembly and attached at an opposite end to the element driver on the second driven element assembly, and said second conductor attached at one end to a first driven element saddle bracket and attached at an opposite end to a second driven element saddle bracket.