1. Field of the Invention
The subject invention relates to antennas. Particularly, the subject invention relates to microstrip antennas for circular polarization applications.
2. Description of the Related Art
Antennas for receiving signals from a satellite, such as Satellite Digital Audio Radio Service (SDARS) signals, are well known in the art. These antennas are routinely carried on vehicles for use with the vehicle's radio receiver. Typically, these antennas are mounted on a metallic roof of the vehicle such that the roof acts as a ground plane for the antenna. Furthermore, these antennas often have a bulky appearance that is not aesthetically pleasing from the outside of the vehicle.
Many modern vehicles incorporate glass into their roof. The amount of glass used can range from a typical sunroof that provides glass over a small portion of the vehicle roof to a panoramic-style glass that spans the entire roof area of the vehicle. Unfortunately, the use of glass in vehicle roof structures reduces the amount of sheet metal that can be used as a ground plane for a satellite antenna. As such, typical satellite antennas suffer from lower performance when disposed on glass.
Therefore, there remains an opportunity for an antenna that may be integrated with glass, such as a glass roof of a vehicle, for receiving signals from a satellite.
The subject invention provides an antenna including a patch element formed of conductive material. The antenna also includes a coupling element formed of conductive material and having an interior edge defining a cavity. The coupling element is disposed non-planar with and generally parallel to the patch element. A plurality of radiating strips are formed of conductive material and arranged as at least one dipole pair. The radiating strips are disposed non-planar with and generally parallel to the patch element. The radiating strips are also disposed within the interior edge of the coupling element. The antenna also includes a first dielectric layer formed of a non-conductive material and sandwiched between the patch element and both the radiating strips and the coupling element. The antenna may also be integrated with a window having a non-conductive pane of transparent material.
The window having the integrated antenna may be a glass roof of a vehicle. The unique structure of the antenna makes it ideal to receive signals from satellites through the glass with performance that is comparable to sheet metal mounted antennas that are prevalent in the prior art. Specifically, the antenna of the subject invention provides radiation pattern coverage at lower elevation angles, i.e., angle coverage as low as 20 degrees, which is the lowest satellite elevation required by SDARS providers.
Other advantages of the present invention will be readily appreciated, as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:
Referring to the Figures, wherein like numerals indicate corresponding parts throughout the several views, an antenna is shown at 10.
Referring to
The window 12 may be a rear window (backlite), a front window (windshield), sunroof, roof window, or any other window or tilter/non-tilter pane of the vehicle 14. The window 12 may alternatively be utilized in non-vehicle applications such as buildings (not shown). The antenna 10 may also be implemented in non-window applications, including, but not limited to, electronic devices such as cellular phones. Of course, those skilled in the art realize other applications for the antenna 10.
The antenna 10 of the illustrated embodiments may be utilized for transmitting and/or receiving radio frequency (RF) signals. Preferably, the RF signal has a circular polarization, such as those utilized by Satellite Digital Audio Radio Service (SDARS) providers, such as XM Radio or Sirius Satellite Radio. More preferably, the antenna 10 of the illustrated embodiments operates on RF signals having a frequency around 2,338 MHz, which corresponds to a commonly utilized SDARS frequency band. The antenna 10 may also be utilized with other signal polarizations and/or at other frequencies, as is readily recognized by those skilled in the art. However, for explanatory purposes, the dimensions of the antenna 10 described hereafter relate to the 2,338 MHz SDARS frequency band. Those skilled in the art appreciate that these dimensions may be modified based on a desired operation of the antenna 10 and should not be read as limiting in any way.
Referring to
Preferably, the patch element 18, as well as the other components of the antenna 10 defined below, are disposed inside of the vehicle 14. As such, the antenna 10 is not easily visible from outside of the vehicle 14, which allows the vehicle 14 to maintain a streamlined and aesthetically pleasing appearance.
In the illustrated embodiments, the patch element 18 defines a generally circular shape. The circular shape assists in providing a uniform radiating effect along an edge of the radiating patch element 18. However, other shapes of the patch element 18 may alternatively be utilized, including, but not limited to, rectangular or triangular shapes. To correspond to the SDARS frequency band described above, the patch element 18 has a diameter of about 20 mm.
The antenna 10 also includes a coupling element 20 formed of conductive material. The conductive material may be a metal or other material that conducts electricity. The coupling element has an interior edge 22 defining a cavity 24. Preferably, the interior edge 22 of the coupling element 20 defines a generally rectangular shape. More preferably, and as shown in the illustrated embodiments, the interior edge 22 of the coupling element 20 defines a square shape. Accordingly, the cavity 24 also defines a square shape. However, the interior edge 22 of the coupling element 20, and the cavity 24, may alternatively define other shapes including, but not limited to, circles, triangles, and other polygons.
The coupling element 20 is disposed non-planar with the patch element 18. More specifically, as shown in
The antenna 10 also includes a plurality of radiating strips 26 formed of conductive material. In one implementation, the radiating strips 26 may be produced with printed and hardened silver paste as is commonly known in the art. In another implementation, the radiating strips 26 may be segments of wire. However, those skilled in the art realize other techniques to implement the radiating strips 26.
As with the coupling element 20, the radiating strips 26 are disposed non-planar with and generally parallel to the patch element 18. As such, the radiating strips 26 are also generally parallel to the coupling element 20. Furthermore, in the illustrated embodiments, the radiating strips 26 are also disposed below the patch element 18.
The radiating strips 26 are arranged as at least one dipole pair (not numbered). In the illustrated embodiment, the plurality of radiating strips 26 is further defined as four radiating strips 26. Furthermore, the four radiating strips 26 are arranged as two dipole pairs in a crossed-dipole pattern, as can be seen in
This crossed-dipole arrangement of the radiating strips 24 assists in providing the antenna 10 in transmitting and/or receiving the RF signal with circular polarization. In the illustrated embodiments, the length of each radiating strip measures about 17 mm. The proximal ends 27 are separated from the common point by about 1 mm. As such, proximal ends 27 of each dipole pair are separated from one another by about 2 mm.
The radiating strips 26 are disposed within the interior edge 22 of the coupling element 20. Said another way, the radiating strips 26 do not contact or overlap the coupling element 20. As such, the radiating strips 26 appear to be disposed within the cavity 24. In the illustrated embodiments, each radiating strip 26 is separated from the interior edge 22 of the coupling element 20 by about 1 mm.
As can be best seen in
The antenna 10 may also include a plurality of feed elements 34 formed of conductive material, as shown in
The antenna 10 preferably includes a ground plane 36 formed of a conductive material for reflecting energy received and/or transmitted by the antenna 10. The ground plane 36 is disposed generally parallel with the patch element 18, the coupling element 20, and the radiating strips 26. The ground plane 36 is also disposed below, i.e., non-planar with, the patch element 18, the coupling element 20, and the radiating strips 26. The ground plane 36 is preferably substantially flat and defines a rectangular shape. More preferably, the ground plane 36 defines a square shape. However, other shapes may also be acceptable. In the illustrated embodiment, the ground plane 36 has a length of about 60 mm and a width of about 60 mm. The ground plane 36 of the illustrated embodiments also defines transit holes (not numbered) to allow the radiating strips 26 to pass through the ground plane 36 without making electrical contact with the ground plane 36.
A first dielectric layer 38 is sandwiched between the patch element 18 and both the radiating strips 26 and the coupling element 20. A second dielectric layer 40 is sandwiched between both the coupling element 20 and the radiating strips 26 and the ground plane 36. The dielectric layers 38, 40 are formed of non-conductive material to provide an insulating layer. In the first and second embodiments, the first dielectric layer 38 has a height of about 5 mm while the second dielectric layer 38 has a height of about 10 mm. The dielectric layers 38, 40 each have a relative permittivity between 1 and 100. Preferably, the relative permittivity of each dielectric layer 38, 40 are different For example, the first dielectric layer 38 may be a plastic and the second dielectric layer 40 may be an air gap. However, it is to be appreciated that the first and second dielectric layers 38, 40 may be formed from other materials. The difference between the relative permittivity of the first and second dielectric layers 38, 40 may be dependent upon the SDARS application and the characteristics of the signal received by the antenna 10.
Both dielectric layers 38, 40 are preferably shaped and sized to align with the coupling element 20 and the ground plane 36. As such, in the illustrated embodiment, the dielectric layers 38, 40 each have substantially square shape with a length of about 60 mm and a width of about 60 mm. The dielectric layers 38, 40 each define respective peripheral sides 42, 44, as can be see in
In a third embodiment, as shown in
The antenna 10 preferably includes a conductive casing 46 formed of a conductive material. The conductive casing 46 is disposed adjacent the peripheral sides 42, 44 of the dielectric layers 38, 40. More specifically, the conductive casing 46 is disposed on the peripheral sides 42, 44. As such, the conductive casing 46 wraps around the entire periphery of the antenna 10, as is shown in
Referring to
Additionally, an amplifier (not shown) may be disposed on or integrated with the feeding network 48. The amplifier is preferably a low-noise amplifier (LNA) such as those well known to those skilled in the art.
The unique structure of the antenna 10 makes it ideal to receive signals from satellites through the window 12. As a measure of success for the claimed invention, development focused on gain characteristics that are equivalent to sheet metal mounted antennas that are prevalent in the prior art. Accordingly, the performance of the subject antenna 10 is comparable to such sheet metal mounted antennas. Specifically, the antenna 10 of the subject invention provides radiation pattern coverage at lower elevation angles, as shown in
The present invention has been described herein in an illustrative manner, and it is to be understood that the terminology that has been used is intended to be in the nature of words of description rather than of limitation. Obviously, many modifications and variations of the invention are possible in light of the above teachings. The invention may be practiced otherwise than as specifically described within the scope of the appended claims. In addition, the reference numerals in the claims are merely for convenience and are not to be read in any way as limiting.
This application claims priority to and the benefit of PCT International Patent Application No. PCT/US2008/014088, filed on Dec. 29, 2008, and U.S. Provisional Application No. 61/063,562, filed Feb. 4, 2008, which is hereby incorporated by reference.
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/US2008/014088 | 12/29/2008 | WO | 00 | 10/26/2010 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO2009/099427 | 8/13/2009 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
3813674 | Sidford | May 1974 | A |
4054874 | Oltman, Jr. | Oct 1977 | A |
4443802 | Mayes | Apr 1984 | A |
4486758 | de Ronde | Dec 1984 | A |
4675685 | Finken | Jun 1987 | A |
4853703 | Murakami et al. | Aug 1989 | A |
5142698 | Koga et al. | Aug 1992 | A |
5208602 | Monser et al. | May 1993 | A |
5233364 | Lefeuvre et al. | Aug 1993 | A |
5280286 | Williamson | Jan 1994 | A |
5293176 | Elliot | Mar 1994 | A |
5300936 | Izadian | Apr 1994 | A |
5453754 | Fray | Sep 1995 | A |
5465100 | Remondiere | Nov 1995 | A |
5703601 | Nalbandian et al. | Dec 1997 | A |
5801660 | Ohtsuka et al. | Sep 1998 | A |
6023244 | Snygg et al. | Feb 2000 | A |
6087989 | Song et al. | Jul 2000 | A |
6680712 | Yamamoto et al. | Jan 2004 | B2 |
6731243 | Taira et al. | May 2004 | B2 |
6940457 | Lee et al. | Sep 2005 | B2 |
7612727 | Schwenke | Nov 2009 | B2 |
7619568 | Gillette | Nov 2009 | B2 |
20060097923 | Li et al. | May 2006 | A1 |
20070080864 | Channabasappa | Apr 2007 | A1 |
20070126638 | Channabasappa | Jun 2007 | A1 |
20070268188 | Guha et al. | Nov 2007 | A1 |
20080129635 | Surittikul et al. | Jun 2008 | A1 |
Number | Date | Country |
---|---|---|
1667276 | Jun 2006 | EP |
1744399 | Jan 2007 | EP |
1775795 | Apr 2007 | EP |
2408149 | May 2005 | GB |
2006-229871 | Aug 2006 | JP |
2007-235592 | Sep 2007 | JP |
WO 2007-106975 | Sep 2007 | WO |
Entry |
---|
English language translation and abstract for JP 2006-229871 extracted from PAJ database Feb. 14, 2011, 33 pages. |
English language translation and abstract for JP 2007-235592 extracted from PAJ database Feb. 14, 2011, 32 pages. |
PCT International Search Report PCT/US2008/014088, dated Mar. 27, 2009, 3 pages. |
Number | Date | Country | |
---|---|---|---|
20110032164 A1 | Feb 2011 | US |
Number | Date | Country | |
---|---|---|---|
61063562 | Feb 2008 | US |