FEATURE INDUSTRIAL ELECTRONICS
BRINGING 5G IMPLEMENTATION TO AUTOMOTIVE APPLICATIONS
Geoff Schulteis, senior antenna applications engineer at Antenova Ltd.discusses antennas for the emerging 5G automotive market, and antenna integration
C
onnected car applications in vehicle diagnostics and “Infotainment” are
already here, and in-car streaming, games and web browsing are set to grow. 5G is very different to 3G and 4G, and offers the potential for new services around autonomous vehicles and remote-controlled driving. While within the vehicle itself, groups of sensors could monitor the condition of brakes, temperature and driving conditions. The key advantages of 5G lie in speed,
latency, and reliability. 5G promises download speeds of 150-250Mbps which is much faster than typical 4G speeds which are usually around 20-30Mbps in the UK. The latency on UK 4G networks is perhaps 50ms, and this will be greatly reduced – the target latency for 5G networks is 1ms. This is far faster than the reaction speed of a human being, so it is a key enabler for new rapid and time-critical processing that will be needed to control autonomous vehicles. 5G networks will provide greater
reliability, ideal for applications where safety is critical. Vehicles will be able to maintain constant connection to the network, so connected fleets of autonomous vehicles will be able to warn each other about traffic or poor road conditions ahead. The European 5G spectrum is primarily in the 3.4GHz – 3.8GHz bands where signals are shorter range and less likely to penetrate walls and obstacles. 5G services will be ideally suited to outdoor use, and the capacity of the 5G networks will be sufficient to support many users simultaneously. Next generation 5G cellular technology
will use antenna systems and MIMO antennas. MIMO (multiple-input multiple-output), means that more than one data signal is transmitted simultaneously over the same channel, typically using two to four antennas. The number of antennas can be increased to tens or even hundreds, thereby massively increasing network capacity and performance. Analysts Gartner say that CCTV is
currently the largest market opportunity for 5G. Then from 2023 onwards, they predict that the automotive sector will use the largest share of 5G IoT solutions.
24 FEBRUARY 2021 | ELECTRONICS
matching circuit to tune the antenna within the target device. Antennas may be the only component
SMD ANTENNA FOR 5G Manufacturers are already bringing 5G components to the market, including antennas. Image 1 shows Antenova’s Lepida SMD
antenna for 5G. it is an embedded antenna which mounts on a printed circuit board. This is a wideband antenna in SMD
form, designed to achieve strong RF performance and high efficiency across a 600MHz to 3800MHz spectrum, i.e. right across the key cellular bands: 617 – 698 MHz, 698 – 798 MHz, 824 – 960 MHz, 1710 – 2170 MHz, 2300 – 2400 MHz, 2500 – 2690 MHz, 3300 – 3800 MHz. It is linear polarised and has been designed to ensure excellent coplanarity. Lepida was developed for the more
demanding applications in 5G, 4G and LTE where antenna performance and reliability make a difference. It was designed to answer the needs of the automotive sector, and it can also be used in aerospace, UAVs, smart metering, remote control and 5G routers. Figure 2 shows key performance values for Lepida antenna SR4L054 across the frequencies.
ANTENNA INTEGRATION The integration of SMD antennas needs care. Many require a ground plane on the host PCB to radiate effectively, this antenna included, and the antenna requires a clearance underneath. Depending on the device environment, Lepida may also require an external
Figure 1:
Antenova’s Lepida antenna SR4L054
that has to be located in a specific physical position on the circuit board. This means it is best to position the antenna early in the design, allowing for the ground plane that the antenna needs to radiate effectively. The ground plane requirement will be stated in the manufacturer’s datasheet. An embedded antenna needs to be placed away from the rest of the circuit – otherwise noise and other components can cause it to detune and degrade performance. The gap between the device’s casing
and the antenna is also important. Plastic has a higher dielectric constant than air, so placing an antenna too close to the case is likely to detune the antenna, and metal casings are usually best avoided. The RF circuitry should be designed
with short transmission lines because these are prone to reflections and signal losses, they can potentially lose as much as 50% of the RF and compromise antenna performance.
Figure 2:
Key performance values for Lepida antenna SR4L054 across the frequencies
DESIGN REVIEW Once the design is complete, there are some checks to ensure optimum wireless performance. The designer should check the suitability of the transmission line, and if the impedance of the transmission line matches the source and RF circuitry. Along the transmission line, spacing between two vias should exceed 5% of the wavelength of the RF signals, and separate vias may be needed for each pin and pad. If the design requires a matching
circuit, for example a pi matching circuit, check that its values enable an impedance match. Advanced wireless designs often use multiple antennas, and may incorporate more than one wireless technology. In these cases, the co- existence of the various antennas will make the design more complex, and the integration will be best done by an antenna specialist.
Antenova Ltd.
www.antenova.com
/ ELECTRONICS
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