Apparatus and method for transferring DC power and RF energy through a dielectric for antenna reception

#The invention relates generally to transmission of radio frequency signals (e.g., SDARS signals) from an antenna across a dielectric such as glass to a receiver disposed in a vehicle, as well as the transmission across glass of power from the receiver to antenna electronics. The invention also relates to an antenna system having DC and RF coupling across a dielectric which uses a relatively low supply voltage and low loss circuit boards and patch arrangement for optimal RF coupling.

#With reference to FIG. 1, a number of antenna systems have been proposed which provide for the transfer of radio frequency (RF) energy through glass or other dielectric surface to avoid having to drill holes, for example, through the windshield or window of an automobile for installation. Glass-mount antenna systems ate advantageous because they obviate the necessity of having to provide a proper seal around an installation hole or other window opening in order to protect the interior of the vehicle and its occupants from exposure to external weather conditions.

#In the conventional antenna system 20 depicted in FIG. 1, RF signals from an antenna 22 are conducted across a glass surface 24 via a coupling device 26 that typically employs capacitive coupling, slot coupling or aperture coupling. The portion of the coupling device 26 on the interior of the vehicle is connected to a matching circuit 28 which provides the RF signals to a low noise amplifier (LNA) 32 at the input of a receiver 34 via an RF or coaxial cable 30. The matching circuit 28 can comprise passive components or traces on a circuit board, for example. The antenna system 20 is disadvantageous because the matching circuit 28, losses associated with the cable 30 and RF coupling (e.g., on the order of 2 to 4 dB or more) cause an increase in system noise. RF coupling losses increase as frequency increases. To reduce coupling losses, a conventional antenna system 20 is preferably implemented using ceramic compositions for circuit boards that are relatively expensive (e.g., Rogers 3003, 4003, 3010, and the like available from Rogers Corporation, Chandler, Ariz.). The cost associated with using these types of materials is 5 times that of a standard FR4 circuit board. A need therefore exists for an antenna system that achieves low RF coupling loss using low cost circuit boards.

#The various aspects, advantages and novel features of the present invention will be more readily comprehended from the following detailed description when read in conjunction with the appended drawings, in which:

#FIG. 1 depicts a conventional antenna system that allows transfer of RF energy across a dielectric such as glass;

#FIG. 2 depicts a conventional antenna system for installation on a building for satellite reception of video signals;

#Throughout the drawing figures, like reference numerals will be understood to refer to like parts and components.

#The system depicted in FIG. 2 is generally a high voltage system, that is, the voltage supplied from an internal source is typically 12 volts to 18 volts. The voltage supplied outdoors, that is, through the dielectric to the externally mounted electronic components such as the LNA 56, is the voltage supplied from the internal source times its efficiency, which can be as low as 50%. Thus, the DC voltage supplied through the dielectric to the externally mounted electronic components is 6 to 9 volts. In satellite radio receivers such as receivers for SDARS, the receiver 48 supplies approximately 5 volts to the externally mounted antenna hardware. In accordance with the present invention, the antenna system is configured to deliver a minimum of 5 volts DC to externally mounted components when the internal supply voltage is only 5 volts.

#With reference to FIG. 3, an antenna system 80 constructed in accordance with an embodiment of the present invention is shown. The antenna system 80 is configured for satellite reception (e.g., SDARS) at a vehicle. The antenna system comprises an interior module 82 for installation inside the vehicle (e.g., in the passenger or engine compartment of an automobile), and an exterior module 84 for installation on the exterior of a vehicle (e.g., on the front or rear windshield or a window of the vehicle). The interior module 82 and the exterior module 84 are preferably mounted on opposite sides of a dielectric such as glass 86 (e.g., an automobile windshield or window). The antenna system 80 preferably employs plural antennas (e.g., a satellite signal antenna 88 and a terrestrial signal antenna 90), and RF and DC coupling. The antenna system can also employ an integral antenna assembly for mounting on the exterior surface of the glass 86 as described in the above-referenced U.S. patent application Ser. No. 09/844,699.