SUPPLEMENT THE INTERNET OF THINGS
DESIGNING ELECTRONIC DEVICES FOR THE IOT USING LP-WAN CONNECTION
LP-WAN is a useful development for networks of “things”, so how do you design the connection to the LP-WAN asks Antenova, designer and manufactures of embedded antennas for networks? Because of the small data capacity, LP-
WAN looks best suited to simple applications, such as tracking, parking, billing or burglar alarms, where the data packets are small, so we can expect to see the most growth in new IoT applications in the oil and gas industries, metering, smart cities, agricultural monitoring, and lighting. One single LP-WAN will be able to run any number of these applications. Designing a product for a LP-WAN should
be no more difficult, and maybe easier than for cellular or Wi-Fi networks. The choice of network will depend upon the nature of the application, the amount of data, distances between the devices, and if the connections are obstructed or line-of-sight. At the device end, the main requirement
will be to select antennas for the correct frequency ranges, and to remember that devices with more than one connection will need more than one antenna. While antennas are generally becoming
T
here is increasing interest in Low Power WANs, (LP-WAN). Low
powered networks such as LoRa and SigFox are not new, but now they are starting to be adopted for significant real-life projects, while some newer network standards, such as Weightless- P, have recently emerged on the market and give the electronics designer more network choices. LP-WANs operate in the lower part of
the radio spectrum, below 1GHz. With an LP-WAN it’s possible to pack more signals down the narrow band by dividing the frequency into many channels to support large numbers of devices. It results in a very low cost network, with no cabling costs because all of the connections are wireless, and there are no cellular or satellite communications costs either. Adding the fact that battery technology
has advanced too, it gives a very efficient network where a number of LP-WAN devices could run for very long periods without any maintenance or energy costs. LP-WAN devices, unlike smartphones, have very low power requirements, so AA batteries or coin batteries could last for
S10 DECEMBER/JANUARY 2017 | ELECTRONICS
many years, as they only need to power tiny bursts of activity. These are just some of the reasons why LP-WANs will be useful for connecting networks of “things”. However, there are some inhibitors to the
use of LP-WANs, the data packets are small, they work across relatively short ranges, they are not realtime, and there can be network interference. Yet there are plenty of situations where these factors are not significant, and numerous new applications which will become viable in the LP-WAN environment, for example tracking and monitoring applications, particularly where the electronic devices move around, such as with tracking pets and livestock. The distances achieved vary, but 2km - 5km may be possible.
THE CONNECTED HOME LP-WAN could also be a good choice for electronic applications in the smart home, because the radio signals can penetrate objects and buildings. By adding antennas to domestic equipment and appliances, they can be connected to an external network to allow off-site maintenance or cloud-based remote controls.
Figure 1:
LP-WAN it’s possible to pack more signals down the narrow band by dividing the frequency into many channels to support large numbers of devices
smaller, their size is ultimately governed by the laws of physics, and they will always ideally require a ground plane of 80mm to 100mm to perform at the sub 1GHz frequency ranges. Yet the devices being created for the Internet of Things will tend to be small – items such as sensors, for example. This presents a challenge to the designer – to maintain the performance of the antenna, whilst designing it into a limited space. It’s important to remember that the
housing material of the device and the position of the antenna can both affect the final performance of the antenna. If the ground plane is too small, the antenna will not perform as well as it should – its efficiency will be reduced, which will reduce its operational range and drain power faster from the batteries. If the designer chooses flexible FPC
antennas, they can be folded or curved and fixed to the underside of the product casing. Whichever style of antenna is selected, the design should be tested to understand how the antenna radiates and how it should be positioned and matched to get the best performance within the device.
Antenova
www.antenova-m2m.com/products T: 01223 810600
/ ELECTRONICS
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