PCB loop antenna 868 MHz for Wi-SUN node

Wi-SUN node key data

Customer: Okra Solar in Australia
Website: okrasolar.com
IoT application: Mesh-grid monitoring and remote maintenance for off-grid power systems
Radio technology: Wi-SUN (868 MHz in Africa)
Frequency range: 868 MHz
Antenna type: PCB loop antenna (integrated, with coax cable)
Special feature: Invisible integration solves range issues and protects against vandalism

Okra Solar in Australia supplies remote African communities with decentralized solar mesh-grids that deliver reliable AC power to last‑mile households. Leaf units (WI-SUN nodes) bring power to homes, while Okra’s communication layer uses a Wi-SUN mesh to send high‑resolution monitoring data to the cloud, even where there is no mobile network. Satelittes in the orbit make the connection to the cloud.

Our team developed a compact 868 MHz PCB loop antenna for Okra’s Wi-SUN border router (gateway). The antenna connects via a short coax cable, so it fits both inside the gateway enclosure and inside the Leaf units, while still matching the Wi-SUN requirements. This keeps the RF design consistent across products and simplifies logistics and maintenance.

The main challenge was limited range in dense mesh networks with many nodes. Large ground planes of PCBs, metal parts in the system, dssplay and nearby non-conductive materials such as plastic and wood degraded antenna efficiency. By tailoring the PCB loop geometry, matching network and its position in the housing, we restored and improved the link budget at 868 MHz. The coax pigtail gives mechanical flexibility: the RF front-end can sit where the electronics demand it, while the antenna sits where RF performance is best.

Compared to external whip antennas, the integrated PCB loop brings several advantages. The antenna is completely hidden inside the device, which reduces theft and vandalism and avoids accidental damage during transport and installation. At the same time, there is no connector corrosion and no need for installers to orient an external antenna. For Okra this means more robust operation in harsh African environments with dust, heat and humidity, and lower total cost over the product lifetime.

Antenna matching and IoT development

Do you need a customised antenna for your IoT product? We support you with antenna matching on your existing design, complete antenna development, or full hardware design for connected devices. Reach out to discuss your PCB layout, housing and RF requirements – together we can turn your link budget into a solid, field‑proven solution.