Flat panel antenna

• US 6,249,254 B1
• Filed: 08/30/2000
• Issued: 06/19/2001
• Est. Priority Date: 02/05/1999
• Status: Expired due to Fees

• Current Assignee: Xertex Technologies, Inc. (Laird Limited)
• Original Assignee: Centurion Industries Incorporated (Laird Limited)
• Inventors: Munson, Robert Eugene, Bateman, Blaine Rexel
• Primary Examiner(s): LE, HOANGANH T
• Application Number:
  US09/651,060
• Time in Patent Office: 293 Days
• Field of Search: H01/Q.138, 343/700.MS, 343/846, 343/702, 343/829, 343/830, 343/906, 343/711, 343/703, 296/00
• US Class Current: 343/700.0MS
• CPC Class Codes: G06F 1/1616 with folding flat displays, e.g. laptop computers or notebooks having a clamshell configuration, with body parts pivoting to an open position around an axis parallel to the plane they define in closed position
• CPC Class Codes: G06F 1/1626 with a single-body enclosure integrating a flat display, e.g. Personal Digital Assistants [PDAs]
• CPC Class Codes: G06F 1/1698 the I/O peripheral being a sending/receiving arrangement to establish a cordless communication link, e.g. radio or infrared link, integrated cellular phone details of antennas disposed inside a computer H01Q1/2266
• CPC Class Codes: H01Q 1/2266 disposed inside the computer
• CPC Class Codes: H01Q 1/243 with built-in antennas
• CPC Class Codes: H01Q 1/3233 particular used as part of a sensor or in a security system, e.g. for automotive radar, navigation systems
• CPC Class Codes: H01Q 1/3291 mounted in or on other locations inside the vehicle or vehicle body
• 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 9/40 Element having extended radiating surface

Abstract

A small size, flat panel, ⅙^th wavelength antenna is provided. A flat copper-clad dielectric substrate is processed on a first flat side to produce a copper triangular or pseudo triangular-shaped radiating element having a linear copper feed line that extends from the triangle apex. The substrate is also processed on its opposite flat side to produce a rectangular-shaped first copper ground plane element that underlies at least a portion of the copper feed line, but does not underlie the copper radiating element. The first side of the substrate may also be processed to produce a second copper ground plane element that is out of physical engagement with both the copper feed line and the copper radiation element. Aligned through holes are formed in the first ground plane element and the substrate. The metal sheath of a coaxial cable connects to the copper ground plane member(s), and the cable center conductor penetrates the aligned through holes and connects to the copper feed line. The antenna substrate may be a portion of a printed circuit board, or the like, that is within a mobile wireless communication device, such as a laptop computer or a cellular telephone. The antenna ground plane element(s) may also function as the ground plane for another antenna, such as a GPS antenna.

Claims

1. A method of determining the physical dimensions of an antenna having a generally triangular radiating element, having a linear feedline, one end of which includes an apex-area that is defined by a linear extension of two inclined sides of said radiation element, and having a ground plane element that is electrically isolated from and that underlies only said feedline and said apex area, said antenna having an input feed of a known impedance that is connected to said feedline, the method comprising the steps of:

selecting a desired center frequency of operation of said antenna;

selecting a height of said radiating element as measured from said end of said feedline to a base line of said radiation element, wherein said height is selected as a function of the wavelength of operation of said antenna and said desired center frequency of operation;

determining a width of said feedline that produces a feedline impedance that is less than said known input feed impedance;

selecting an apex angle for said apex area;

construct an antenna having physical dimensions in accordance with the above-defined steps;

connecting a first electrical instrument to said input feed and energizing said antenna with a frequency band that includes said desired center frequency;

using a second electrical instrument to determine a bandwidth of operation of said energized antenna; and

adjusting said height of said radiating element and/or said width of said feedline to achieve a desired bandwidth of operation of said energized antenna wherein said desired center frequency is within said desired bandwidth of operation.

2. The method of claim 1 wherein said desired bandwidth of operation is a maximum bandwidth of operation.

3. The method of claim 1 wherein said input feed is connected to a portion of said feedline that excludes said apex area.

4. The method of claim 1 wherein:

said antenna is a ⅙

^th wavelength antenna; and

said selected width of said feedline is about equal to the value in inches of 1.2 times the width of a feedline having an impedance equal to said known impedance.

5. The method of claim 1 wherein said apex angle is about 65-degrees.

6. The method of claim 1 wherein said energization of said antenna with a frequency band comprises energizing said antenna with a band of frequencies that includes said desired center frequency, plus and minus about 20-percent of said desired center frequency.

7. The method of claim 1 wherein:

said input feed is connected to a portion of said feedline that excludes said apex area;

said antenna is a ⅙

^th wavelength antenna;

said selected width of said feedline is about equal to the value in inches of 1.2 times the width of a feedline having an impedance equal to said known impedance

said apex angle is about 50-degrees;

said first electrical instrument is a network analyser;

said energizing of said antenna with a frequency band comprises energizing said antenna with a band of frequencies from about 20-percent less than said desired center frequency to about 20-percent greater than said desired center frequency; and

said second electrical instrument is a network analyser.

8. A method of designing the physical size of a planar antenna having a generally triangular shaped and a planar radiating element having a base side and two inclined sides that terminate at opposite ends of said base side, having a rectangular-shaped feedline, one width end of which includes an apex area that is defined by a linear extension of said inclined sides of said radiation element, said width end of said feedline providing an apex side for said radiating element, and having a ground plane element that is electrically isolated from but underlies only said feedline and said apex area, said antenna having an input feed of a known impedance that is connected to said feedline, the method comprising the steps of:

selecting a desired center frequency of operation of said antenna;

selecting a height of said radiating element as measured from said width end of said feedline to said base line;

said height being selected as a function of a wavelength of operation of said antenna and said desired center frequency of operation;

determining a length of said width end of said feedline that produces a feedline impedance that is less than said known impedance;

selecting an apex angle for said apex area;

construct an antenna having physical dimensions in accordance with the above-defined steps;

connecting a first electrical instrument to said input feed and energizing said antenna with a frequency band that includes said desired center frequency;

using a second electrical instrument to determine a bandwidth of operation of said energized antenna; and

adjusting said height of said radiating element and/or said width of said width end of said feedline to achieve a desired bandwidth of operation of said energized antenna such that said desired center frequency is generally centered within said desired bandwidth of operation.

9. The method of claim 8 wherein said desired bandwidth of operation is a maximum bandwidth of operation, and including the step of repetitively adjusting said height of said radiating element and/or said width of said width end of said feedline.

10. The method of claim 9 wherein:

said inclined sides of said radiating element are of equal length;

said apex angle is about 50-degrees; and

said feedline is centered upon a line that bisects said apex angle.

11. The method of claim 10 wherein said input feed is connected to a portion of said feedline that excludes said apex area.

12. The method of claim 11 wherein:

said antenna is a ⅙

^th wavelength antenna;

said known input impedance of said input feed is about 50 ohms; and

said width of said width end of said feedline is initially selected to be about equal to the value in inches of 1.2 times the width of a feedline having an impedance of 50 ohms.

13. The method of claim 12 wherein said energization of said antenna with a frequency band comprises energizing said antenna with a band of frequencies that includes said desired center frequency, plus and minus about 20-percent of said desired center frequency.