Integrated microstrip helmet antenna system

• US 5,886,667 A
• Filed: 09/10/1997
• Issued: 03/23/1999
• Est. Priority Date: 10/01/1996
• Status: Expired due to Fees

• Current Assignee: Probir K. Bondyopadhayay
• Original Assignee: Probir K. Bondyopadhayay
• Inventors: Bondyopadhayay, Probir K.
• Primary Examiner(s): Wong, Don
• Assistant Examiner(s): Ho, Tan
• Application Number:
  US08/926,836
• Time in Patent Office: 559 Days
• Field of Search: 343/700 MS, 343/718, 343/853
• US Class Current: 343/700.0MS
• CPC Class Codes: A42B 3/30 Mounting radio sets or communication systems
• CPC Class Codes: H01Q 1/276 for mounting on helmets
• CPC Class Codes: H01Q 1/38 formed by a conductive layer on an insulating support patch antennas H01Q9/0407; microstrip dipole antennas H01Q9/065; microstrip slot antennas H01Q13/106; transmission line microstrip antennas H01Q13/206; manufacturing reflecting surfaces using insulating material for supporting the reflecting surface H01Q15/142
• CPC Class Codes: H01Q 21/205 providing an omnidirectional coverage turnstile aerials H01Q21/26
• CPC Class Codes: H01Q 21/24 Combinations of antenna units polarised in different directions for transmitting or receiving circularly and elliptically polarised waves or waves linearly polarised in any direction circularly polarised patch antennas H01Q9/0428; circularly polarised horns H01Q13/0241; cross-polarised horns H01Q13/0258; polarisation converters H01Q15/242; cross-polarised rear feeds H01Q19/136; crossed polarisation dual antenna H01Q25/001
• CPC Class Codes: H01Q 9/0414 in a stacked or folded configuration
• CPC Class Codes: H01Q 9/0435 using two feed points
• CPC Class Codes: H04B 2001/3866 carried on the head

Abstract

An integrated helmet and omnidirectional microstrip antenna system comprising a ballistic helmet constructed of rigid non-metallic material with a sheet of dielectric material as the top layer thereof and an omnidirectional microstrip antenna system having one or more antenna radiator elements affixed to the top surface of the dielectric sheet. The antenna radiator elements are circularly polarized by a microstrip feed network designed to provide circular polarization of a desired sense. A conductive layer of metallic material bonded to the underside of said dielectric sheet and integrated in the helmet structure serves as the electrical ground for the antenna.

Claims

1. An integrated helmet and microstrip antenna system which is adapted to provide substantially omnidirectional transmission and reception of microwave and millimeter wave signals as well as reception of Global Positioning System Signals, said integrated helmet antenna system comprising:

a helmet structure comprising a sheet of dielectric material as the top layer thereof;

a first circularly polarized microstrip antenna radiator element bonded on the top side of said dielectric sheet, said sheet having an electrically conducting ground layer bonded on one side to the bottom of said sheet to form a layer of said helmet structure and serve as an electrical ground for the antenna system;

an array of three more antenna radiating elements bonded to the top side of said dielectric sheet and arranged on the helmet in a ring array around said first antenna element, said antenna elements each adapted to be excited and circularly polarized by a dual feed microstrip feed line structure with appropriate pre-determined amplitude and relative phase distributions among said antenna radiator elements so as to produce a wide angle antenna radiation pattern acceptable for a specific antenna performance requirement, said feed structure comprising a microstrip feed line originating from a feed point near the base of the helmet where it is connectable to a coaxial connector for coupling to a power signal source and signal collection point, said feed line running upwards to the top center region of the helmet where it divides into a pair of branches in predetermined power ratios, the first branch of said first pair further dividing into a second pair of branches in predetermined power ratios with one branch of said second pair feeding said first circularly polarized element at the center top of the helmet, and the other branch of said second pair being routed around said top antenna element at a distance to avoid undesired coupling and extending radially outward from the top of the helmet to feed one of the other three antenna elements at a predetermined location, the second branch of said first pair further dividing into another pair of branches in predetermined power ratio, with each branch of said other pair being routed about the said element at the top center of the helmet with sufficient separation amongst the feed lines so as to minimize feed line coupling, said two branches of said other pair spreading radially outward from the top of the helmet with each connecting to a different one of the remaining two antenna elements which are in predetermined coupling locations on the helmet.

2. The omnidirectional helmet antenna system as set forth in claim 1 wherein each microstrip antenna radiator element and the microstrip feed line structure is printed on said dielectric sheet.

3. The omnidirectional helmet antenna system as set forth in claim 2 wherein the integrated printed antenna structure is covered by a thin layer of dielectric material which serves as a radome for the antenna system.

4. The omnidirectional helmet antenna system as set forth in claim 1 wherein the dielectric substrate on which the antenna elements are mounted are made of unwoven aramid materials.

5. The omnidirectional helmet antenna system in claim 1 wherein the helmet is made of woven aramid material.

6. The omnidirectional helmet antenna system as set forth in claim 1 wherein the circularly polarized microstrip antenna elements are circular microstrip patches.

7. The omnidirectional helmet antenna system as set forth in claim 1 wherein each circularly polarized radiator element is fed by microstrip line matched T-junction type power dividers.

8. The omnidirectional helmet antenna system as set forth in claim 1 wherein each circularly polarized antenna radiator element is a microstrip line quadruple fed element.

9. The integrated helmet and microstrip antenna system as set forth in claim 1 wherein said electrically conducting ground layer is in the form of a wire screen.

10. The integrated helmet and microstrip antenna system as set forth in claim 9 wherein the size of a conducting wire screen opening of the wire mesh is defined by a side of the opening having a dimension approximately of the order of 0.01 times the wavelength of the antenna operating frequency in the media in which the mesh is embedded.

11. An integrated helmet and microstrip antenna system which is adapted to provide substantially omnidirectional transmission and reception of microwave and millimeter wave signals as well as reception of Global Positioning System Signals, said integrated helmet antenna system comprising:

a helmet structure comprising a sheet of dielectric material as the top layer thereof;

at least one microstrip antenna radiator element bonded on the top side of said dielectric sheet;

an electrically conducting ground layer bonded on one side to the bottom of said sheet to form a layer of said helmet structure and serve as an electrical ground for the antenna system;

a microstrip feeder network comprising a microstrip feed line originating from a feed point near the base of the helmet where it is adapted to be connected to a coaxial connector for coupling to a power signal source and signal collection point, said feed line running upwards from said feed point to a point near said antenna radiator element where it divides to provide a junction power divider, said power divider being coupled to said antenna radiator element at dual feed points located on mutually orthogonal input axes of the radiator element coupled thereto for providing a 90°

phase shift in the signal to one of said dual feed points with respect to the other so as to generate circular polarization of the desired sense.

12. The integrated helmet and integrated microstrip antenna system as set forth in claim 11 wherein the helmet is made of woven aramid material.

13. The integrated helmet and integrated microstrip antenna system as set forth in claim 11 wherein said sheet of dielectric material is made of unwoven aramid material.

14. The integrated helmet and integrated microstrip antenna system as set forth in claim 11 wherein said electrically conducting ground layer is in the form of a wire mesh having mesh openings wherein the side of a mesh opening is approximately of the order of 0.01 times the operating frequency of the antenna in the media in which said mesh is embedded.

15. An integrated helmet and microstrip antenna system which is adapted to provide substantially omnidirectional transmission and reception of microwave and millimeter wave signals as well as reception of Global Positioning System Signals, said integrated helmet antenna system comprising:

a helmet structure comprising a sheet of dielectric material as the top layer thereof, an electrically conducting ground layer bonded on one side to the bottom of said sheet to form a layer of said helmet structure and serve as an electrical ground for the antenna system;

a first circularly polarized microstrip antenna radiator element bonded on the top side of said dielectric sheet near the top center of the helmet structure;

a plurality of additional antenna radiating elements bonded to the top side of said dielectric sheet and arranged on the helmet in a ring array around said first antenna element, said antenna elements each adapted to be excited and circularly polarized by a dual feed microstrip feed line structure with appropriate pre-determined amplitude and relative phase distributions among said antenna radiator elements so as to produce a wide angle antenna radiation pattern acceptable for a specific antenna performance requirement, said feed structure comprising a microstrip feed line originating from a feed point near the base of the helmet where it is connectable to a power signal source and signal collection point, and a plurality of T-junction power dividers wherein each of said power dividers is coupled to a different one of said antenna radiator elements at feed points located on mutually orthogonal input axes of the radiator element coupled thereto so as to provide inputs with a 90°

phase shift of one of said inputs with respect to the other whereby said antenna system will generate circular polarization radiation of the desired sense.

16. An integrated helmet and microstrip antenna system as set forth in claim 15 wherein said helmet structure and said sheet of dielectric material are of aramid material.

17. An integrated helmet and microstrip antenna system as set forth in claim 15 wherein said helmet structure is of woven aramid material and said dielectric sheet is of non-woven aramid material.

18. An integrated helmet and microstrip antenna system as set forth in claim 15 wherein said electrically conducting ground layer is a wire mesh having square mesh openings with side dimensions approximately of the order of 0.01 times the operating frequency of the antenna in the media in which the mesh is embedded.

19. An integrated helmet and microstrip antenna system adapted to provide omnidirectional wide angle transmission and reception of microwave and millimeter wave signals as well as reception of Global Positioning System Signals, said integrated helmet antenna system comprising:

a helmet structure comprising a sheet of dielectric material as the top layer thereof;

an electrically conducting ground wire screen bonded on one side to the bottom of said sheet to form a layer of said helmet structure and serve as an electrical ground for the antenna system;

a first circularly polarized microstrip antenna radiator element bonded on the top side of said dielectric sheet near the top center of the helmet structure; and

a plurality of additional antenna radiating elements bonded to the top side of said dielectric sheet and arranged on the helmet in a ring array around said first antenna element, said antenna elements each adapted to be excited and circularly polarized by a dual feed microstrip feed line structure with appropriate pre-determined amplitude and relative phase distributions among said antenna radiator elements so as to produce a wide angle antenna radiation pattern acceptable for a specific antenna performance requirement, said feed structure comprising a microstrip feed line originating from a feed point near the base of the helmet where it is connectable to a power signal source and signal collection point and further including a plurality of T-junction power dividers wherein each of said power dividers is coupled to a different one of said antenna radiator elements at feed points located on mutually orthogonal input axes of the radiator element coupled thereto so as to provide inputs with a 90°

phase shift of one of said inputs with respect to the other whereby said antenna system will generate circular polarization radiation of a desired sense.

20. An integrated helmet and microstrip antenna system as set forth in claim 19 wherein said helmet structure and said sheet of dielectric material are of aramid material.

21. An integrated helmet and microstrip antenna system as set forth in claim 19 wherein the conducting screen openings are of a size and configuration so as to attenuate the electromagnetic field of the antenna transmission by at least 60 dB.