Cellular antennas with improved front-to-back performance

• US 5,872,544 A
• Filed: 02/04/1997
• Issued: 02/16/1999
• Est. Priority Date: 02/04/1997
• Status: Expired due to Fees

• Current Assignee: PHAZAR Corp. (QAR Industries, Inc.)
• Original Assignee: Gec-Marconi Hazeltine Corporation Electronic Systems Division
• Inventors: Schay, Gary A.
• Primary Examiner(s): Wong, Don
• Assistant Examiner(s): PHAN, THO GIA
• Application Number:
  US08/794,705
• Time in Patent Office: 742 Days
• Field of Search: 343/725, 343/727, 343/729, 343/730, 343/810, 343/817, 343/890, 343/891, 343/892, 343/767, 343/770, 343/771, 343/793, 343/794, 343/872, 343/819, 343/832, 343/834, 343/835
• US Class Current: 343/727
• CPC Class Codes: H01Q 1/246 specially adapted for base stations
• CPC Class Codes: H01Q 13/10 Resonant slot antennas
• CPC Class Codes: H01Q 19/104 using a substantially flat reflector for deflecting the radiated beam, e.g. periscopic antennas periscopic fed Cassegrain antennas H01Q19/191; passive relays H04B7/145
• CPC Class Codes: H01Q 21/10 Collinear arrangements of substantially straight elongated conductive units
• CPC Class Codes: H01Q 21/12 Parallel arrangements of substantially straight elongated conductive units travelling-wave antennas comprising transmission line loaded with transverse elements H01Q11/02; Yagi antennas H01Q19/30
• CPC Class Codes: H01Q 21/29 Combinations of different interacting antenna units for giving a desired directional characteristic H01Q25/00 takes precedence
• CPC Class Codes: H01Q 21/293 one unit or more being an array of identical aerial elements adaptive arrays H01Q3/2605

Abstract

A 90 degree azimuth beamwidth is achieved in a narrow cellular antenna, by inclusion of sidewalls. To improve front-to-back performance, slot radiating elements extending through the sidewalls re-radiate signals behind the antenna. Signals re-radiated from the slot elements are effective to partially cancel signals otherwise radiated behind the antenna as a result of diffraction. H-shaped slots are described for sidewall use and side-to-side slots are described for endwall use. Slots may be dielectrically loaded by contiguous portions of a radome.

Claims

1. A cellular antenna, providing an azimuth beamwidth and having improved front-to-back performance, comprising:

a plurality of vertically aligned dipole radiators in a single vertical column;

a reflective backwall positioned behind said dipole radiators and having a width inadequate to achieve said azimuth beamwidth;

sidewalls extending forward from said backwall to increase beam focus to achieve said azimuth beamwidth; and

a plurality of slot radiating elements formed in said sidewalls to re-radiate signals behind said antenna to partially cancel signals otherwise radiated behind said antenna.

2. A cellular antenna as in claim 1, additionally including a radome of dielectric material having side portions extending contiguous to said slot radiating elements and partially determining effective slot capacitance.

3. A cellular antenna as in claim 1, wherein each said slot radiating element is H-shaped and aligned with its central portion extending in a forward direction.

4. A cellular antenna as in claim 3, wherein each said slot radiating element includes a relatively narrow central portion providing a slot of predetermined capacitance and relatively wider end portions extending across the ends of the central portion.

5. A cellular antenna as in claim 1, wherein each said slot radiating element is proportioned to be non-resonant within an operating frequency band.

6. A cellular antenna as in claim 1, additionally including:

endwalls extending forward from the top and bottom of said backwall; and

a plurality of slot radiating elements formed in said endwalls to re-radiate signals behind said antenna.

7. A cellular antenna as in claim 6, wherein each said endwall slot radiating element comprises a slot extending in a side-to-side direction.

8. A cellular antenna as in claim 6, wherein said plurality of dipole radiators is replaced by a single vertically aligned dipole radiator.

9. A cellular antenna as in claim 1, wherein said plurality of dipole radiators is replaced by a single vertically aligned dipole radiator.

10. A cellular Antenna as in claim 1, wherein said antenna provides a beam having a 90 degree azimuth beamwidth within a predetermined frequency range.

11. A cellular antenna as in claim 1, wherein the antenna is rotated so that said dipole radiators and column of radiators are not vertically aligned.

12. A cellular antenna, including a reflector with re-radiating slots to improve front-to-back performance, comprising:

a plurality of radiators arrayed in a vertical column;

said reflector cooperating with said radiators, said reflector including sidewall portions extending forward; and

a plurality of slot radiating elements formed in said sidewalls to re-radiate signals behind said reflector to improve front-to-back performance by partially canceling signals otherwise radiated behind said antenna, said slot radiating elements proportioned to be non-resonant within an operating frequency band.

13. A cellular antenna as in claim 12, additionally including a radome of dielectric material having side portions extending contiguous to said slot radiating elements and partially determining effective slot capacitance.

14. A cellular antenna as in claim 12, wherein each said slot radiating element is H-shaped, and aligned with its central portion extending in a direction transverse to said array of radiators.

15. A cellular antenna as in claim 14, wherein each said slot radiating element includes a relatively narrow central portion providing a slot of predetermined capacitance and relatively wider end portions extending across the ends of the central portion.

16. A cellular antenna as in claim 12, wherein said radiators are vertically aligned dipole radiators.

17. A cellular antenna as in claim 12, wherein said plurality of radiators is replaced by a single vertically aligned dipole.

18. A cellular antenna as in claim 12, wherein the antenna is rotated so that said column of radiators are not vertically aligned.

19. A cellular antenna, providing an azimuth beamwidth and having improved front-to-back performance, comprising:

a plurality of vertically aligned dipole radiators in a single vertical column;

a reflective backwall of planar rectangular shape positioned behind said dipole radiators and having a width inadequate to achieve said azimuth beamwidth;

sidewalls of planar rectangular shape and extending forward from said backwall to increase beam focus to achieve said azimuth beamwidth; and

a plurality of H-shaped slot radiating elements formed in said sidewalls to re-radiate signals behind said antenna to improve front-to-back performance by partially canceling signals otherwise radiated behind said antenna.

20. A cellular antenna as in claim 19, wherein each said slot radiating element includes a relatively narrow central portion providing a slot of predetermined capacitance and relatively wider end portions extending across the ends of the central portion.

21. A cellular antenna as in claim 19, additionally including a radome of dielectric material having side portions extending contiguous to said slot radiating elements and partially determining effective slot capacitance.

22. A cellular antenna as in claim 19, wherein said plurality of dipole radiators is replaced by a single vertically aligned dipole.