NB-IoT Antenna ESD and Surge Protection

Overview

Narrowband IoT (NB-IoT) is a wireless communication technology that provides low power consumption, wide coverage, and high reliability for IoT devices. It is a variant of LTE designed to support large-scale, low-power, low-data-rate IoT communications.

Main characteristics of NB-IoT

Low power consumption: optimized RF design and narrowband transmission enable long operating periods and extended battery life.
Wide coverage: NB-IoT leverages existing LTE infrastructure to extend coverage, including indoor and underground areas.
High reliability: retransmission mechanisms and error checking help ensure reliable data delivery, even in poor signal conditions.
Low cost: by using existing LTE networks, additional infrastructure investment is minimized, lowering deployment and maintenance costs.

NB-IoT is widely applied in areas such as smart cities, smart homes, smart metering, and environmental monitoring, providing reliable connectivity for large-scale deployments.

Need for ESD and surge protection at the antenna

NB-IoT devices are used in both indoor and outdoor environments. Static charge can accumulate between the device and its antenna, leading to electrostatic discharge (ESD) that can damage circuitry. Outdoor exposure also introduces the risk of electrical surges from events such as lightning. Therefore, protection components should be placed at the antenna interface to limit overvoltage propagation and reduce damage from electrical surges.

Proposed protection approach

A protection solution is proposed for antenna interfaces to provide ESD and surge mitigation while preserving RF signal integrity.

Key points:

Use low-capacitance protection devices at the antenna interface to minimize impact on RF performance.
For modules with a 3.3 V operating voltage, a low-junction-capacitance diode such as ULC3311CDN is recommended.
For 5 V modules, a low-junction-capacitance ESD diode such as ULC0511CDN30 is recommended. The specified devices support contact discharge up to 30 kV and air discharge up to 30 kV.
To meet IEC 61000-4-5 surge testing requirements, add a gas discharge tube (GDT) at the front end, for example SMD4532-090NF or 2R090-5S.