Dual-band transmission device and antenna therefor

• US 6,545,640 B1
• Filed: 06/14/2001
• Issued: 04/08/2003
• Est. Priority Date: 11/08/1999
• Status: Expired due to Term

• Current Assignee: RPX Corporation
• Original Assignee: Alcatel SA (Nokia Corporation)
• Inventors: Herve, Pascal, Coupez, Jean-Philippe, Kouam, Charles Ngounou
• Primary Examiner(s): LE, HOANGANH T
• Application Number:
  US09/868,067
• Time in Patent Office: 663 Days
• Field of Search: H01/Q.138, 343/700.MS, 343/702, 343/846, 343/826, 343/828
• US Class Current: 343/700.0MS
• CPC Class Codes: H01Q 1/243 with built-in antennas
• CPC Class Codes: H01Q 1/246 specially adapted for base stations
• CPC Class Codes: H01Q 5/357 using a single feed point
• CPC Class Codes: H01Q 9/0421 with a shorting wall or a shorting pin at one end of the element H01Q9/0414 takes precedence

Abstract

The antenna (1) of this system is a microstrip antenna. A rear edge (10) of the body (31) of its patch (6) is provided with a short-circuit (S) by which a quarter-wave type primary resonance can be excited from a connecting line (C1). A slot (17) penetrates the patch from its periphery and separates a body from a tail (33) which remains connected to the body by a passage (32). A secondary resonance mode utilises the body, the passage and the tail. It can be excited from the same connection line at a frequency which is twice that of the primary resonance. The short-circuit can be obtained by components attached to the edge of the substrate of the antenna and can then have inductive, resistive and controlled components. The invention applies in particular to implementing a two-mode mobile radio system using the GSM and DCS standards.

Claims

1. A two-band transmission system including:

a signal processor adapted to be tuned in two operating bands centered on respective predetermined center frequencies to transmit and/or receive an electrical signal in each of the two bands,

a microstrip antenna, and

an antenna connection system including electrical conductors connecting the processor to the antenna for coupling said electrical signal to radiated waves,

wherein the antenna includes;

a conductive ground plane,

a conductive patch having a periphery,

an electric substrate positioned between said conductive ground plane and said conductive patch,

a short-circuit formed at said periphery, and

a separator slot having an origin consisting of an opening in said periphery, said slot penetrating said patch from said origin,

wherein said short-circuit and said separator slot enable two resonances to be established in said antenna, one of said two resonances is of the quarter-wave type with an at least virtual electric field node fixed by said short-circuit, constitutes a primary resonance and has a primary frequency substantially equal to one of said two center frequencies, and the other of said two resonances constitutes a secondary resonance having a secondary frequency substantially equal to the other of said two center frequencies,

and wherein said electrical conductors of the connection system include said ground plane and a main antenna coupling conductor which is part of said patch to enable said antenna to be coupled to said signal processor around each of said two center frequencies,

which transmission system is characterized in that said separator slot extends in said patch as far as a rear end of said slot located at a sufficiently small distance from said periphery for said slot to divide said patch partly into a body including said main antenna coupling conductor and said short-circuit and a tail free of said short-circuit and electrically connected to said connection system only by means of said body and a passage consisting of an area of said patch between a back and said periphery.

2. The transmission system according to claim 1, said system being characterized in that said separator slot is at a distance from said periphery greater than the distance from said back to said periphery over a major portion of its length and on both sides.

3. The transmission system according to claim 1, said system being characterized in that said separator slot is at a distance from said periphery greater than the distance from said back to said periphery over all of its length and on both sides except in the vicinity of said origin.

4. The transmission system according to claim 1, said system being characterized in that said origin of the separator slot is near said short-circuit so as to confer on said two resonances respective resonance paths which both extend from said short-circuit, one of said two paths extends only in said body and the other of said two paths extends in said body and in said tail.

5. The transmission system according to claim 4, said system being characterized in that the edges of said separator slot are concave on the same side as said body and convex on the same side as said tail.

6. The transmission system according to claim 1, wherein said antenna includes:

said electrical substrate which has two mutually opposed main surfaces which extend in horizontal directions of said antenna and respectively constitute a bottom surface and a top surface,

a bottom conductive layer which extends over said bottom surface and constitutes said ground plane of said antenna,

a top conductive layer which extends over an area of said top surface over said ground plane and constitutes said patch,

said short-circuit, which electrically connects said patch to said ground plane from a segment of said periphery of said patch, and

an antenna coupling system forming part of said antenna connection system.

7. The transmission system according to claim 6, said system being characterized in that said antenna coupling system is a microstrip line including:

a strip constituting said main antenna coupling conductor, and

said ground plane.

8. The transmission system according to claim 6, said system being characterized in that said patch is of generally rectangular shape and said periphery includes:

an edge provided with the short-circuit and constituting a rear edge,

an edge opposite said rear edge and constituting a front edge, and

two lateral edges joining said rear edge to said front edge and respectively constituting a leading edge and a tail edge,

and in which system a length of said patch extends between said rear edge and said front edge in a longitudinal direction constituting one of said horizontal directions and a width of said patch extends between its two lateral edges in one of said horizontal directions constituting a transverse direction.

9. The transmission system according to claim 8, said system being characterized in that said body has an excrescence extending in the plane of said patch in the vicinity of said passage.

10. The transmission system according to claim 8, said system being characterized in that said separator slot extends from said rear edge of the patch to said front edge as far as a rear end of said slot at a distance from said two lateral edges and said front edge, whereby said body is connected to said tail by a passage having a length and a width, said length extends in said transverse direction, said width extends in said longitudinal direction between said front edge and said back of said slot, said slot separates said rear edge into a body base forming part of said body and provided with said short-circuit and a tail base forming part of said tail, said tail base has a width in said transverse direction, a tip of said tail consists of the area where said tail joins with said passage and has a width extending in said transverse direction, said tail has a length extending in said longitudinal direction from said tail base to said tip, and a width of said tail is defined at each point of said length and extends in said transverse direction.

11. The transmission system according to claim 10, said system being characterized in that said width of the base of the tail is greater than said width of the tip of said tail.

12. The transmission system according to claim 11, said system being characterized in that said width of the tail increases from said tip to said base of said tail through a plurality of intermediate values between said widths of said tip and said base.

13. The transmission system according to claim 12, said system being characterized in that said length of the tail is from 50% to 100% of said length of the body and the ratio of said secondary frequency to said primary frequency is from 1.9 to 2.1.

14. The transmission system according to claim 12, said system being characterized in that said width of the base of the tail is from 50% to 150% of said width of the body, said passage and said tip of said tail constitute a connecting system of said tail, a narrower width of said system constitutes an effective tail connection width and this effective width is from 10% to 70% of said width of said base.

15. The transmission system according to claim 8, said system being characterized in that said origin of the separator slot and said short-circuit are near the point common to said rear side and said tail side, the edges of said separator slot are concave on the same side as the body and convex on the same side as said tail, so as to impart two said two resonances two resonance paths respectively extending from said short-circuit, and one of said two paths extends only in said body and the other extends in said body and in said tail.

16. The transmission system according to claim 6, said system being characterized in that said short-circuit has a relatively high impedance at said primary frequency so that said primary resonance is substantially different from a resonance that could be induced in said antenna in the vicinity of said frequency if said short circuit had no impedance, said impedance is at the same time relatively low at said frequency to fix an electric field node of said resonance in the vicinity of said short-circuit and said node is at least virtual.

17. The system according to claim 16, said system being characterized in that said impedance of the short-circuit has an inductive component.

18. The system according to claim 16, said system being characterized in that said impedance of the short-circuit has a resistive component.

19. The system according to claim 16, said system being characterized in that said impedance of the short-circuit has a controlled component.

20. The system according to claim 16, said system being characterized in that said short-circuit includes at least one discrete component connected between said patch and said ground plane of the antenna.

21. The system according to claim 6, said system being characterized in that a dielectric substrate includes in at least part of its area two mutually distinct and superposed layers respectively constituting a bottom dielectric layer carrying said ground plane and a top dielectric carrying said patch.

22. The system according to claim 21, said system being characterized in that said top dielectric layer has a higher relative permittivity than said bottom layer and said two layers extend all over the area of said substrate.

23. The system according to claim 21, said system being characterized in that said antenna includes a conductive insert extending in a portion of the area of said patch between said bottom dielectric layer and said top dielectric layer and said portion extends at least under said passage.

24. The transmission system of claim 1, wherein a width of said separator slot is less at said opening than a width of said separator slot at a portion of said separator slot proximal to said rear end.