With every passing yr, customers have increased expectations for wi-fi connectivity from their autos—and design engineers are on the forefront of making techniques to satisfy these expectations. Wi-fi connectivity and associated purposes come in several kinds, starting from elaborate infotainment techniques to automobile management options akin to route planning, navigation, and identification of hazards.
For management and highway security, autos of tomorrow will have the ability to talk utilizing vehicle-to-everything (V2X) techniques. “The whole lot” can embody a mobile community, roadside infrastructure, particular person autos, bicyclists, and pedestrians. Mobile V2X (C-V2X) is a normal for V2X outlined by the worldwide mobile communication requirements group 3GPP.
C-V2X can make the most of both vehicle-to-network (V2N) communications through mobile networks or it might probably use direct communication, generally known as PC5. PC5-based direct communication features, that are just like a walkie-talkie, allow the automobile to speak with different autos or close by gadgets with out an middleman. This functionality addresses one of many shortcomings of V2N, which requires cell community protection, and lots of endure from lengthy latency as a result of the sign is shipped by a number of phases (system to cell tower, cell tower to web, web to second cell tower, and cell tower to second system). This additionally may be too time-consuming to supply crucial knowledge in a well timed method.
PC5 communications is optimized for shut communication, inside 1.5 km and line of sight, since customers on this vary are most related to the protected operation of the automobile. Longer-range communications may be managed by V2N gadgets and the mobile community. The fast rise of automated driver help techniques (ADAS) and security features is fueling demand for sooner and extra dependable PC5-based connectivity. With some security and regulatory organizations contemplating requiring PC5 communication to realize a 5-star security score, PC5 is evolving from a nice-to-have to vital characteristic. Because of this, automobile designs should incorporate antennas and supporting structure that ship reliable V2X connectivity through PC5.
Automotive engineers should deal with challenges and potential pitfalls for antenna techniques early within the design course of. Optimizing efficiency of the antenna system entails sustaining glorious sign integrity by minimizing vitality loss, or sign attenuation, each inside and outside the automobile. Listed below are 5 suggestions system designers can apply to assist guarantee autos are able to high-speed C-V2X communications required for a spread of security features.
Tip #1: Know Your Hyperlink Finances
An instance of a Cable Loss Hyperlink Finances. MOLEX
Designing the antenna system for optimum efficiency is a posh course of, and step one ought to be mapping out a hyperlink finances. The hyperlink finances predicts how a lot vitality is misplaced between the transmitter in Automobile A and the receiver in Automobile B (and vice versa for the return message). At 5.9 GHz, the frequency used for PC5-based vehicle-to-vehicle (V2V) communications, vitality loss may be extra important than at decrease frequencies, making it much more crucial to determine the hyperlink finances earlier than any additional steps in design are taken.
When establishing the hyperlink finances, designers should take into account vitality loss inside the antenna block; inside the cable block, together with any required connectors; and within the telematic management unit block. Mapping this info is important to designing the system to counteract any extreme vitality loss. As design work proceeds, the antenna system design may be refined as needed to take care of a suitable degree of sign attenuation and guarantee dependable and efficient operation of the TCU.
Tip #2: Maximize Sign Power with Correct Antenna Placement
KOOL99/ISTOCK/GETTY IMAGES PLUS VIA GETTY IMAGES
Earlier than designers can lay out the automobile antenna system, optimum, efficient antenna placement must be decided. Bodily placement of the antennas on the automobile has a serious impact on sign power. On the similar time, the selection of location for the antennas should be balanced in opposition to the general design and aesthetics of the automobile.
When evaluating placement, the model (e.g., shark fin or blade) and placement (e.g., entrance windshield or bumper) of the antenna are main concerns. Location will have an effect on multidirectional connectivity, with sign power various considerably by route relying on the antenna location. For instance, shark fins are positioned on the automobile roof, ideally on the highest level. This presents the potential for 360-degree protection across the automobile. However custom-made shark fins steadily comprise many inner antenna parts, akin to 5G mobile, high-precision GNSS, Wi-Fi, or AM/FM, that may block the sign and degrade efficiency. Counterintuitively, glass roofs are particularly detrimental to antenna efficiency at 5.9 GHz. Because of this, PC5 parts are steadily added to the again of the shark fin and are centered on rear-facing efficiency.
Antennas positioned within the windshield or inside the bumper can have their efficiency affected by close by gadgets and structural supplies. For an antenna on the entrance left nook of the automobile within the bumper, there are prone to be “blind spots” to the suitable and rear as a result of any sign would wish to go by a good portion of the automobile’s construction, thereby dramatically lowering the sign power. Polar plots are used to visualise blind spots by figuring out instructions with poor sign power. With this info, the antenna model or location may be revised to enhance connectivity.
A range system for antennas presents benefits. MOLEX
In lots of circumstances, optimizing sign power may be completed by utilizing two antennas that complement one another’s protection (assuming the TCU accommodates two antennas). With an antenna on the entrance and a second on the rear, or with antennas at reverse corners, every antenna maintains one of the best sign power within the route of the opposite’s blind spot. That is referred to as a range system. Utilizing polar plots of sign power, antenna placement may be deliberately designed to maximise sign power and enhance the pace and reliability of the automobile’s PC5 connection.
Tip #3: Optimize Your Cables and Interconnects
As soon as the antenna places and TCU are decided, the subsequent step within the design course of focuses on routing cables and choosing interconnect choices to optimize system efficiency. A major supply of sign attenuation may be cable loss. That is primarily affected by the cable’s sort and size in addition to the connectors utilized. Cable loss may be managed, nonetheless, however designing for optimum sign power requires a spread of things to be thought of. These elements embody automobile structure in addition to value, weight, and element manufacturability.
The high-speed FAKRA Mini connector. MOLEX
Shorter cable runs and high-performance 50-Ohm coax cables may also help cut back cable loss. With extra environment friendly cables, although, come trade-offs in value and weight. Excessive-performance wire is heavier, including weight to the automobile, and costlier. It can be tougher and time-consuming to put in. For these causes, cable lengths ought to be stored as quick as potential, however this should be evaluated alongside antenna placement calls for in addition to the general automobile structure and wiring harness. Electrical connectors also can make a serious distinction in total system efficiency, each in managing cable loss and making certain dependable efficiency. Excessive-performance, automotive-grade connectors, akin to Molex Excessive-Pace FAKRA Mini (HFM) Connectors, additionally may also help cut back cable loss.
As with many design choices, optimizing intra-vehicle connectivity whereas limiting cable loss is a balancing act between assembly system efficiency objectives with limiting value and weight. The hyperlink finances serves as a key consider managing these priorities.
Tip #4: Incorporate a Compensator, If Wanted
In lots of autos, significantly these using two antennas, longer cable runs will likely be needed. On cables that run over two meters, sign attenuation is a major gating issue to high efficiency, sometimes pointing to the necessity for a bi-directional amplifier, or compensator. The compensator can enhance efficiency by boosting sign power in transmit mode to offset vitality loss within the system. In obtain mode, the compensator locks within the signal-to-noise ratio. The hyperlink finances will spotlight the necessity for a compensator for longer cable runs which are all too typically included in at present’s techniques.
The compensator also needs to be agnostic, which means it should work with totally different system protocols from main PC5 chipset suppliers, though clients will steadily customise performance. For the everyday antenna system, an automotive-grade, protocol-agnostic compensator, such because the Molex V2X Compensator, presents a number of benefits. It incorporates a PC5 antenna factor; presents a excessive diploma of design flexibility, together with totally different achieve management settings for inbound and outbound indicators; and its rugged design helps guarantee dependable system operation.
Tip #5: Completely Take a look at the System at Each Stage
All through the design course of, it’s critical to check the automobile antenna system repeatedly, each on a element foundation and as an entire system. Making certain the system and its parts work as designed is crucial to avoiding surprises when the design is finalized.
Early within the design course of, simulation testing is important. Using calculations derived from simulating the sign attenuation of every element within the system is important in creating the hyperlink finances. Then, because the design is refined, simulation testing may be revised as wanted. As soon as the design is within the prototype part, a testing facility ought to be used to supply a full vary of information on the operation of the whole system. Molex leverages superior, devoted testing amenities in Europe and North America to find out the efficiency of the system in a variety of situations. Utilizing this info to validate simulations and the hyperlink finances will assist make sure the antenna system works as required.
The Rising Significance of Connectivity
As security techniques in autos start to rely extra more and more on PC5-based C-V2X connectivity, it should change into more and more very important for automotive designers to make sure that autos can preserve dependable mobile connections with close by autos and different gadgets. Shoppers and regulatory our bodies would require autos to realize excessive requirements for connectivity to satisfy security expectations.
To perform this, it’s essential to design automobile antenna techniques from the beginning with concerns for sign attenuation challenges. Taking these steps and optimizing end-to-end operation of the antenna system because the automobile design progresses will considerably enhance connectivity and total system operation to ship efficiency that meets client demand. This, in flip, will enhance buyer satisfaction and allow related autos of tomorrow to ship the specified ranges of efficiency, consolation and effectivity, most significantly, with the very best ranges of driver and passenger security.
Considering studying extra? Steered studying: SAE specification J3161
