Smart Conformal Antenna – A Technical Challenge

With emerging trends of the future towards conformal design of automotive antennas, there are global trends in communication technologies that must be incorporated into all coming telematics solutions. These technologies are facing two major requirements: communication technologies use higher frequencies and bandwidth and more technologies need to be supported simultaneously.
All these trends can be well covered by conformal (smart) antenna concepts. Here at HARMAN we are designing and implementing them while being fully prepared to overcome the technical challenges they present.


Gerhard Grossberger is Director of Product Management at HARMAN Business Unit Telematics. Gerhard has 20+ years of experience in defining systems and business models for telematics products and services. He is sharing his expertise in bringing wireless technologies into solutions with a new quality of user experience. Here Gerhard answers questions that he is commonly asked about the world of Conformal Antenna.​

1.  What is a conformal smart antenna?
The principle is the same as a conformal antenna, also known as a conformal flat system, that follows the outline of the car. But a conformal smart antenna goes one step further. It includes not only the receive and transmit antenna elements, but also all the electronics of a conventional TCU - like application processor, memory, wired interfaces to the E&E-Architecture of the car. This is what makes this kind of antenna smart and intelligent.

2.  What are the real advantages compared to traditional antennas?​
Conformal antennas convert the height of traditional antennas into a flat surface. This surface structure enables the integration of more radio technologies as conventional antennas can support. The main reason of this is because distances between antenna elements can be optimized for a better coexistence of different radio technologies at a small footprint. And this coexistence is very important. Passengers in a car expect that all radio services shall be available everywhere and simultaneously.

A conformal smart antenna brings the electronics very close to the antenna elements, reducing the connection length between antennas and the radio chipsets to a minimum. Knowing that every meter of cable cause signal loss and distortions, a conformal smart antenna offers an optimized performance - more transmit power as well as better receiver sensitivity. Especially on higher frequencies as used in WiFi, 5G or V2X, this gives a huge benefit.

3.  Which technologies can be incorporated?​
​Due to its flat design, conformal antennas and conformal smart antennas can support more technologies than conventional systems. Here is a list of wireless radio technologies that have been already demonstrated, or even realized:

  • 2G, 3G, 4G and 5G cellular networks, up to 4x4 MIMO
  • Bluetooth and Bluetooth Low Energy
  • WiFi (both 2.4 and 5 GHz), up to 2x2 MIMO
  • V2X (C-V2X and DSRC)
  • GNSS single and dual band
  • RKE
  • TPMS
  • UWB​

4.  What are the biggest challenges?
The compact and highly integrated design of a conformal smart antenna generates challenges that need to be addressed during system design, antenna placement, mechanical concept and thermal (cooling) concept.

The first challenge, and maybe it's the biggest, is to be solved is to support all requirements from different domains and find the best fit for our customers. There are requirements and restrictions from the OEMs car line (dimensions, materials, connector positions, manufacturing process etc.) as well as for example temperatures that apply on the roof of a car, and safety regulations that must be followed (rollover, eCall etc.).  And of course, all radio technologies need to coexist and work on their best possible performance.

To address all these topics in a best way, we combine best practices from all required departments, including expertise in antenna simulation and measurement facilities.

5.  What performance can a smart antenna achieve?

When looking to a conformal antenna, many people first think that such an antenna may not have similar performance like traditional antennas. This is because of its flat design, and no antenna elements look above the (metal) roof of a car. The expectation might be that the surrounding metal influences the performance.

But we need to consider that HARMAN conformal antennas use latest state-of-the-art technology. One antenna element is not just a simple piece of PCB, it's much more. Our conformal antenna elements have complex design metrics, using optimal combination of material and form factor. They also leverage from the available space of its flat design and are optimized for omnidirectional radiation patterns.​

​​​We have up a lot of work on these optimizations, both simulations but also real-world testing. And especially all the performance measurements we did under realistic conditions, show better performance than conventional antenna concepts. Better performance enables better user experience. That is why HARMAN has highest demands on this.​

6.  Is a conformal smart antenna cheaper than traditional antenna?

To answer this question correctly, we need to look on the overall system cost. These include the TCU and antenna, but also potentially other cost like cables, connectors, manufacturing and others. A traditional telematics system in a modern car has around 4 to 6 antennas implemented at the roof, with the TCU mounted somewhere under the dashboard. The need for RF cables in such an environment might be between 24 and 40 meters. This is a huge cost impact, and it is eliminated by using a conformal smart antenna. And of course, all these cables need connectors, generate weight, must be mounted in a harness and may cause warranty issues.

Beside the cost of money there is also cost of performance. The cables used in the above example cause signal attenuation. There are high performance cables available, but with the impact of much higher cost. Implementing RF cabling is always a compromise, ending up in degradation of user experience.

7.  How does V2X technology​​ fit into a conformal antenna?

V2X is a fully integrated part in HARMAN's conformal smart antenna concept. Independent of the used technology (DSRC or C-V2X), the requirements regarding antenna design are identical. Direct vehicle-to-vehicle communication requires a signal radiation at the full 360 degree surrounding of the vehicle - at a very flat opening angle in the vertical direction.

Antennas are typically mounted at the back end of the vehicle roof. This position is a very good place in general. But for V2X it has an impact on poor coverage of the area in front of the vehicle. To overcome this, a common approach is to place one V2X antenna directly inside the conformal (smart) antenna module. This antenna radiates mainly to the back side.

A second V2X antenna is typically mounted behind the front wind screen, radiating to the front side. The combination of these two V2X antennas is a good approach for sending and receiving V2X direct link messages 360 degrees around the car.

8.  Is a conformal smart antenna future proof?

Conformal antenna design in general is a common trend in the automotive market. Traditional antenna concepts are expected to disappear in the near future. And bringing the TCU electronics close to the antennas is another trend that we see. That said, the short answer is: Yes. Smart conformal antennas are not a short hype, but more of is a global trend that will go its way, starting now from premium brands and reaching the mass market soon.​

Even today we can see already a number of vehicles on the road with invisible antennas. OEMs put a lot of effort into hiding antennas on many locations around the car. Both OEMs and their customers want to get rid of all the visible antennas. The smart conformal antenna​​​​ concept solves these issues with a much more cost-efficient approach.​

For more information on HARMAN Conformal Antenna, click here​ to download this document summarizing the entire interview that was recently conducted.​

More information about Smart Conformal Antenna

Gerhard Grossberger

Gerhard Grossberger

Associate Director, Engineering and R&​D - Telematics at HARMAN International​​

Connect with the Author:LinkedIn​​​​

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