The new wireless module iM282A from IMST GmbH enables up to 10 km range in the license-free 2.4 GHz band. It uses the LoRa modulation with frequency spread and is suitable even for battery-powered applications.
In practice, the radio applications often require high ranges in both outdoor and indoor space. In Europe, such applications are often implemented in the license-free sub-GHz frequency ranges at 433MHz or 868MHz. Since the low attenuation characteristics prevail in these frequency bands due to the low frequencies, larger ranges can be achieved with comparable transmission levels than in the 2.4 GHz frequency band.
However, this advantage is offset by two disadvantages of these frequency bands:
● Legally allowed duty cycle. For example, the transmission duration is limited to 1 percent (that is 36s per hour).
● The fact that the sub-GHz frequency bands are not harmonized worldwide.
Especially the latter can lead to enormous costs for the necessary radio approval outside of Europe.
Especially home automation applications such as lighting, heating, locking systems, air conditioners, and utility meters are often developed because of the requirement for longer range, in the sub-GHz frequency range. The limitation by the duty cycle is accepted because the application by nature rarely transmits data or the transmission frequency of the most battery-powered devices is limited by the battery capacity itself.
