Cellular antenna structure for integration within a vehicle

A cellular antenna structure for integration in a vehicle includes a ground plane to follow a slope of a spoiler chassis. The spoiler chassis is a portion of the vehicle covered by a spoiler. The cellular antenna structure also includes a cellular antenna orthogonal to the ground plane and electrically connected to the ground plane and a structural support affixed to the ground plane to maintain a fixed position of the cellular antenna orthogonal to the ground plane.

INTRODUCTION

The subject disclosure relates to a cellular antenna structure for integration within a vehicle.

Vehicles may include one or more cellular antennas for communication with one or more cellular networks. A vehicle occupant may couple a personal cellular device (e.g., smartphone, tablet) with a vehicle communication system (e.g., via Bluetooth connectivity). A cellular antenna of the vehicle may then implement communication via a cellular base station. Accordingly, it is desirable to provide a cellular antenna structure for integration within a vehicle.

SUMMARY

In one exemplary embodiment, a cellular antenna structure in a vehicle includes a ground plane to follow a slope of a spoiler chassis. The spoiler chassis is a portion of the vehicle covered by a spoiler. The cellular antenna structure also includes a cellular antenna orthogonal to the ground plane and electrically connected to the ground plane and a structural support affixed to the ground plane to maintain a fixed position of the cellular antenna orthogonal to the ground plane.

In addition to one or more of the features described herein, the cellular antenna is shaped to fit completely within a volume defined by the spoiler.

In addition to one or more of the features described herein, the cellular antenna is shaped as a plate with one or more bends.

In addition to one or more of the features described herein, every dimension of the cellular antenna is less than a wavelength corresponding with a lowest operating frequency of the cellular antenna.

In addition to one or more of the features described herein, every dimension of the cellular antenna is less than a quarter of the wavelength corresponding with the lowest operating frequency of the cellular antenna.

In addition to one or more of the features described herein, the cellular antenna structure also includes a metal carrier between the spoiler chassis and the ground plane.

In addition to one or more of the features described herein, the metal carrier is electrically connected to the spoiler chassis and is affixed to the spoiler chassis.

In addition to one or more of the features described herein, the metal carrier is electrically connected to the ground plane and is affixed to the ground plane.

In addition to one or more of the features described herein, the metal carrier includes an opening to connect a cable from the vehicle to the ground plane.

In addition to one or more of the features described herein, the structural support is plastic.

In another exemplary embodiment, a method of fabricating a cellular antenna structure for a vehicle includes fabricating a ground plane to follow a slope of a spoiler chassis. The spoiler chassis is a portion of the vehicle covered by a spoiler. The method also includes affixing a cellular antenna orthogonal to the ground plane and electrically connected to the ground plane and affixing a structural support to the ground plane to maintain a fixed position of the cellular antenna orthogonal to the ground plane.

In addition to one or more of the features described herein, the method also includes shaping the cellular antenna to fit completely within a volume defined by the spoiler.

In addition to one or more of the features described herein, the shaping includes shaping the cellular antenna as a plate with one or more bends.

In addition to one or more of the features described herein, the method also includes sizing the cellular antenna such that every dimension of the cellular antenna is less than a wavelength corresponding with a lowest operating frequency of the cellular antenna.

In addition to one or more of the features described herein, the sizing includes sizing every dimension of the cellular antenna to be less than a quarter of the wavelength corresponding with the lowest operating frequency of the cellular antenna.

In addition to one or more of the features described herein, the method also includes affixing a metal carrier to the ground plane, the metal carrier being configured to be disposed between the spoiler chassis and the ground plane.

In addition to one or more of the features described herein, the method also includes configuring the metal carrier to be electrically connected to the spoiler chassis and affixed to the spoiler chassis.

In addition to one or more of the features described herein, the method also includes configuring the metal carrier to be electrically connected to the ground plane.

In addition to one or more of the features described herein, the method also includes fabricating the metal carrier with an opening to connect a cable from the vehicle to the ground plane.

In addition to one or more of the features described herein, the method also includes fabricating the structural support from plastic.

DETAILED DESCRIPTION

As previously noted, a vehicle may include one or more cellular antennas to facilitate communication between a cellular device in the vehicle and a cellular network. The cellular communication may be performed at sub-6 gigahertz (GHz) frequencies. For example, the communication may use a frequency range on the order of 617 megahertz (MHz) to 5 GHz. Prior cellular antennas designs include at least a portion of the antenna protruding from a surface of the vehicle. This may be undesirable from the standpoint of aesthetics and aerodynamic performance.

Embodiments of the systems and methods detailed herein relate to a cellular antenna structure for integration within a vehicle. According to exemplary embodiments, the entire cellular antenna is contained within a volume of a rear spoiler of a vehicle such that no portion of the antenna protrudes from the vehicle. The ground plane of the cellular antenna is parallel with and electrically connected to the chassis of the vehicle and the antenna is oriented to maximize its effective height and thereby its efficiency. The size and shape of the cellular antenna are designed to obtain a complete fit within the volume defined by the spoiler without sacrificing radiation efficiency.

In accordance with an exemplary embodiment,FIG.1is a block diagram of a vehicle100that includes a cellular antenna structure200(FIG.2) for integration within the vehicle100. The exemplary vehicle100shown inFIG.1is an automobile101. In alternate embodiments, the vehicle100may be a pick-up truck, sport utility vehicle, or another type of vehicle. The vehicle100is shown with a spoiler110at the rear edge of the roof105. The exemplary spoiler110is between the roof105and the rear windshield115, as shown. In alternate embodiments, the cellular antenna structure200may be located within a volume defined by other fascia of the vehicle100.

The vehicle100includes a spoiler chassis120, which is a part of the vehicle frame that acts as a structural support for the spoiler110and is also the part of the vehicle that is covered by the spoiler110. The spoiler chassis120is metal and is a sloped transition between the roof105and the rear windshield115, as shown. As further discussed with reference toFIG.2, this spoiler chassis120acts as an attachment point for the cellular antenna structure200. The vehicle100may include additional components (e.g., sensors, displays) such as a controller130to facilitate the cellular communication from within the vehicle100using the cellular antenna structure200. The controller130may include processing circuitry that may include an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that executes one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality.

FIG.2details the cellular antenna structure200that is integrated within the vehicle100according to one or more embodiments. Specifically, the cellular antenna structure200includes the cellular antenna210, a ground plane220(e.g., printed circuit board) that is electrically conductive, a metal carrier240to which the ground plane220is electrically connected and affixed and which is electrically connected and affixed to the spoiler chassis120, and a support structure230on the ground plane220that holds the cellular antenna210in a fixed position relative to the ground plane220and metal carrier240. The spoiler110is indicated along with a portion of the roof105. The volume201defined by the spoiler110is also indicated. While the spoiler chassis120is electrically conductive, the spoiler110itself has dielectric properties. As previously noted, the size, shape, and orientation of the cellular antenna210facilitates a complete fit within the spoiler110(i.e., with no portion of the antenna structure200protruding outside the spoiler110). As also noted, the design of the cellular antenna structure200according to one or more embodiments controls radiation efficiency of the cellular antenna210based on the design features detailed.

One of the design features of the cellular antenna structure200is that the cellular antenna210is a monopole antenna that is electrically small. The term electrically small refers to the fact that the cellular antenna210is shorter than the wavelength of signals transmitted and received. Specifically, every dimension of the cellular antenna210is less than the wavelength corresponding to the lowest operating frequency of the cellular antenna210. For example, every dimension of the cellular antenna210may be less than a quarter of the wavelength corresponding to the lowers operating frequency. While a monopole antenna is traditionally a straight rod, the cellular antenna210is a monopole antenna that is shaped to fit within the volume201of the spoiler110. Thus, the size is based on the operating frequency and the corresponding wavelength (e.g., length of cellular antenna210is half the wavelength) and the shape is designed such that the cellular antenna210fits completely in the volume201within the spoiler110. The shape may also be based on frequency response of the cellular antenna210. That is, for example, modeling or simulation may be used to determine the frequency response resulting from a particular shape of the cellular antenna210.

For the exemplary case shown inFIG.2, the lowest operating frequency may be 617 MHz. In this case, the cellular antenna210may have a length that is less than a quarter of the wavelength that corresponds with 617 MHz. The cellular antenna210shape includes two bends215in the plate that makes up the monopole cellular antenna210, one of which is occluded by the support structure230. As previously noted, the number and location of bends215may be selected to ensure a fit within the volume201defined by the spoiler110and may additionally be based on the resulting frequency response.

In addition to size and shape, another design feature of the cellular antenna structure200relates to the orientation of the cellular antenna210relative to the ground plane220. To be clear, the ground plane220is not horizontal but, instead, conforms to the slope of the spoiler chassis120. The spoiler chassis120is angled (e.g., 45 degrees) down from the roof105, which is shown as horizontal in the exemplary case. The roof105may have a curvature in alternate embodiments and in different vehicles100. As shown, the cellular antenna210is orthogonal to the ground plane220. The portion of the cellular antenna210that couples to the ground plane220(occluded by the support structure230inFIG.2but visible inFIG.3) is perpendicular to the ground plane220, which means that it is not vertical because, as noted, the ground plane220is not horizontal.

This relative orientation results in a maximum effective height for the cellular antenna210. The effective height, also referred to as effective length, is the height of the center of radiation of the cellular antenna210above the ground plane220and effects the efficiency of the cellular antenna210. Specifically, the effective height is the ratio of induced voltage to incident electric field. This ratio is maximized by the orientation of the cellular antenna210relative to the ground plane220shown inFIG.2. If the cellular antenna210were vertical (i.e., the portion of the cellular antenna210that couples to the ground plane220were vertical), then the cellular antenna210would be closer to the spoiler chassis120and the roof105, resulting in capacitance and decreased effective height and, consequently, decreased efficiency. Thus, in the arrangement ofFIG.2, the orientation that provides maximum effective height can be seen as the orientation that keeps the cellular antenna210farthest from the spoiler chassis120.

FIG.3is an isometric view of the cellular antenna structure200that is integrated within the vehicle100according to one or more embodiments. The metal carrier240is shown affixed to the ground plane220of the cellular antenna210via screws235. According to alternate embodiments, the metal carrier240and the ground plane220may be electrically connected and affixed with another type of fastener. The support structure230may be a plastic or other non-conductive part affixed to the ground plane220and arranged to support and fix the cellular antenna210with respect to the ground plane220. As noted with reference toFIG.2, the perpendicular arrangement between the ground plane220and the part of the cellular antenna210coupled to the ground plane220results in maximized effective height and, thus, efficiency of the cellular antenna orientation shown inFIG.3. An attachment point310used to attach the metal carrier240to the spoiler chassis120is indicated. A screw may be inserted in the attachment point310, for example.

FIG.4shows the metal carrier240of the cellular antenna structure200that is integrated within the vehicle100according to one or more embodiments. As previously noted, the metal carrier240is electrically connected to the spoiler chassis120on one side and to the ground plane220on the other. The metal carrier240may include an opening410for a cable to the ground plane220, for example. Attachment points420to affix the metal carrier240to the ground plane220are indicated. Screws235may engage each of the attachment points420, for example. Additional attachment points310that are used to affix the metal carrier240to the spoiler chassis120are also indicated.