Patent Application
20170324143
This invention relates generally to an RF connector assembly for connecting a thin film, planar antenna to a connector and, more particularly, to an RF connector assembly for connecting a thin film, co-planar waveguide (CPW) antenna adhered to automotive glass to a FAKRA-type connector.
Modern vehicles employ various and many types of antennas to receive and transmit signals for different communications systems, such as terrestrial radio (AM/FM), cellular telephone, satellite radio, dedicated short range communications (DSRC), GPS, etc. The antennas used for these systems are often mounted to a roof of the vehicle so as to provide maximum reception capability. Further, many of these antennas are often integrated into a common structure and housing mounted to the roof of the vehicle, such as a “shark-fin” roof mounted antenna module. As the number of antennas on a vehicle increase, the size of the structures required to house all of the antennas in an efficient manner and providing maximum reception capability also increases, which interferes with the design and styling of the vehicle. Because of this, automotive engineers and designers are looking for other suitable areas on the vehicle to place antennas that may not interfere with vehicle design and structure.
One of those areas is the vehicle glass, such as the vehicle windshield, which has benefits because glass typically makes a good dielectric substrate for an antenna. For example, it is known in the art to print AM and FM antennas on the glass of a vehicle where the printed antennas are fabricated within the glass as a single piece. However, these known systems are generally limited in that they can only be placed in a vehicle windshield or other glass surface in areas where viewing through the glass is not necessary.
SMB connectors are commonly employed for connecting RF elements, such as an antenna to a coaxial cable. Often times, SMB connectors include an over-molded plastic structure to provide a robust mechanical connection. This combination of an SMB connector with the over-molded plastic is commonly known in the art as a FAKRA-type connector. Thus, for antennas designed and implemented on a planar structure, such as automotive glass, a low profile connector typically needs to be employed to transition from the CPW antenna feed structure to the FAKRA-type connector to enable the antenna to be connected to the coaxial cable.
The present invention discloses and describes an RF connector assembly that provides a proper impedance connection between a CPW antenna mounted on automotive glass, or other suitable dielectric structures, to a FAKRA-type connector for connecting the antenna to a coaxial cable. The connector assembly includes a printed circuit board (PCB) having a top surface and a bottom surface and being adhered to the glass. Vias are provided through the PCB to make electrical contact between metallization planes on the top surface and the bottom surface of the PCB. Terminals that are part of the connector extend through some of the vias, where ground terminals provide mechanical stability and make electrical contact with the metallization planes on the bottom surface of the PCB and a signal terminal provides an electrical connection to the antenna radiating element. The PCB is adhered to a substrate on which the antenna is mounted so that the metallization planes and microstrip lines make electrical contact with a CPW feed structure that feeds the antenna.
Additional features of the present invention will become apparent from the following description and appended claims, taken in conjunction with the accompanying drawings.
The following discussion of the embodiments of the invention directed to a connector assembly for providing an RF connection between a thin film, flexible antenna adhered to a dielectric structure and a FAKRA-type connector is merely exemplary in nature, and is in no way intended to limit the invention or its applications or uses. For example, the discussion herein talks about the connector assembly being applicable to connect a CPW antenna mounted on automotive glass to a FAKRA-type connector. However, as will be appreciated by those skilled in the art, the connector will have application for connecting other electronic devices on other types of substrates.
It may be desirable to provide a thin film, CPW antenna on the windshield 16, the rear window 18, or any other window or dielectric structure on the vehicle 10, where the antenna is flexible to conform to the shape of the particular dielectric structure, and where the antenna can be mounted at any suitable location on the dielectric structure, including locations on the windshield 16 that the vehicle driver needs to see through. The antenna may operate in a frequency band suitable for various communications systems, such as AM/FM radio antennas, DSRC antennas, satellite radio antennas, GPS antennas, cellular antennas, including MIMO antennas, etc. The antenna can be a wideband monopole appliqué antenna that is installed directly on the surface of the dielectric structure by a suitable adhesive. The antenna structure can be designed to operate on automotive glass of various physical thicknesses and dielectric properties, where the antenna structure operates as intended when installed on the glass or other dielectric since in the design process the glass or other dielectric is considered in the antenna geometry pattern development.
The antenna 30 can be formed by any suitable low loss conductor, such as copper, gold, silver, silver ceramic, metal grid/mesh, etc. If the antenna 30 is at a location on the vehicle glass that requires the driver or other vehicle occupant to see through the glass, then the antenna conductor can be any suitable transparent conductor, such as indium tin oxide (ITO), silver nano-wire, zinc oxide (ZnO), etc. Performance of the antenna 30 when it is made of a transparent conductor could be enhanced by adding a conductive frame along the edges of the antenna 30 as is known in the art.
The thickness of automotive glass may vary approximately over 2.8 mm-5 mm and have a relative dielectric constant εr in the range of 4.5-7.0. The antenna 30 includes a single layer conductor and a co-planar waveguide (CPW) feed structure to excite the antenna radiator. The CPW feed structure can be configured for mounting the connector 38 in a manner appropriate for the CPW feed line or for a pigtail or a coaxial cable. When the connector 38 or the pigtail connection to the CPW line is completed, the antenna 30 can be protected with the passivation layer 36. In one embodiment, when the antenna 30 is installed on the glass, a backing layer of the transfer tape can be removed. By providing the antenna conductor on the inside surface of the vehicle windshield 22, degradation of the antenna 30 can be reduced from environmental and weather conditions.
As will be discussed in detail below, the present invention proposes a suitable low profile RF connector assembly that can be used in place of the connector 38 for connecting the antenna structure 20 to a coaxial cable through a FAKRA-type connector. More specifically, the RF connector assembly provides desirable features including proper impedance matching to couple a CPW antenna mounted on vehicle glass to the FAKRA-type connector. The connector assembly will have application for antennas employed for any of the communications systems referred to above, and in, for example, the 500 MHz-6.0 GHz frequency band.
The connector assembly 60 also includes a PCB 80 having a top surface 82 and a bottom surface 84 and being mounted to the top surface 64 of the substrate 62, as will be discussed in detail below.
Four via holes 102 are provided through the PCB 80 and the metallization planes 88 and 96, and are provided around the slots 90 and 98, as shown, where the spacing between the vias 102 matches the spacing between the terminals 48. Further, a via 104 is provided through the PCB 80 and the microstrip lines 92 and 100, and is positioned to accept the signal pin 50 of the connector 40. The connector 40 is positioned on the top surface 82 of the PCB 80 so that the terminals 48 align with the vias 102 and the signal pin 50 aligns with the via 104 so that the terminals 48 and the pins 50 extend through the PCB 80. A suitable soldering process is then employed to secure the connector 40 to the PCB 80 so that the terminals 48 make electrical contact with the metallization planes 88 and 96 and the signal pin 50 makes electrical contact with the microstrip lines 92 and 100, where the terminals 48 provide mechanical rigidity. Additional optional vias 106 and 108 can be provided through the PCB 80, the metallization planes 88 and 96, and the microstrip lines 92 and 100, and be filled with a suitable metal to make further electrical contact between the metallization planes 88 and 96 and the microstrip lines 92 and 100.
The top surface 64 of the substrate 62 includes alignment dots 110 provided on both the metallization plane 68 and the microstrip line 72, as shown. The alignment dots 110 are aligned with the vias 102 and 104 so that the PCB 80 is properly oriented relative to the substrate 62. The PCB 80 is adhered to the substrate 82 by a suitable adhesive layer 112 that allows electrical contact between the metallization plane 96 and the metallization plane 68, and the microstrip line 100 and the microstrip line 72. Thus, the microstrip line 72 is electrically coupled to the signal pin 50. It is noted that all of the metallization planes and microstrip lines being discussed can be optically transparent, as discussed above.
In other embodiments, the antenna may be provided on a bottom surface 114 of the substrate 62, such as an inside surface of the vehicle glass.
The foregoing discussion discloses and describes merely exemplary embodiments of the present invention. One skilled in the art will readily recognize from such discussion and from the accompanying drawings and claims that various changes, modifications and variations can be made therein without departing from the spirit and scope of the invention as defined in the following claims.
This application claims the benefit of the priority date of U.S. Provisional Patent Application Ser. No. 62/332,666, titled, Thin Film Antenna to Fakra Connector, filed May 6, 2016.
| Number | Date | Country | |
|---|---|---|---|
| 62332666 | May 2016 | US |
