Wireless Connectivity & IoT / LoRaWAN

LoRaWAN: Technology and Filter Requirements

LoRaWAN (Long Range Wide Area Network) is the leading technology for the Internet of Things (IoT) when it comes to extreme range and minimal power consumption. Based on Chirp Spread Spectrum (CSS) modulation, LoRaWAN operates in unlicensed sub-GHz bands, primarily at 868 MHz in Europe and 915 MHz in North America. The technical challenge lies in the extremely high receiver sensitivity of up to -148 dBm, which allows signals to be detected even far below the noise floor. However, this sensitivity makes LoRaWAN gateways extremely vulnerable to overloading from neighboring high-power cellular services such as LTE Band 20 (800 MHz) or GSM 900.

Wainwright Instruments provides specialized high-performance filters for these high-sensitivity environments, designed to precisely isolate the narrowband LoRa spectrum from broadband interference. Since LoRaWAN gateways are often installed at exposed locations in parallel with cellular base stations, extreme skirt steepness and high stopband attenuation outside the ISM bands are required. Our filter solutions protect receiver front-ends from saturation and ensure stable connectivity for thousands of end nodes per gateway, even in spectrally burdened environments.

Typical Deployment Scenarios:

LoRaWAN filters from Wainwright are essential components for LPWAN infrastructures that must guarantee reliable data transmission over distances of up to 15 km.

Smart City Infrastructure: In urban environments, our filters secure the communication of networked streetlights and parking sensors in the 868 MHz band against massive interference from public cellular networks and Wi-Fi offloading.
Smart Grid & Utility Metering: For remote reading of water and gas meters located in deep shafts, our filters ensure maximum receiver sensitivity to fully exploit the deep indoor penetration of LoRaWAN.
Agricultural Technology (Smart Farming): In expansive agricultural areas, our filter solutions secure signal quality for soil moisture sensors and livestock tracking systems in the 915 MHz band by eliminating interference from neighboring rural LTE stations.
Industrial Condition Monitoring: In factory halls, our RF components protect LoRa gateways from electromagnetic pulses from heavy machinery, enabling uninterrupted monitoring of critical parameters.
Logistics & Asset Tracking: For tracking containers in expansive port areas, we offer filters that minimize multipath interference and stabilize signal purity in metal-rich environments with strong reflections.
Environmental Monitoring: In disaster protection systems, such as river level gauges, our highly robust filters guarantee reliable alerting over long distances, even under extreme weather conditions.
Building Automation: In large office complexes, our filters prevent hundreds of battery-powered LoRa sensors from being limited in range by neighboring in-house cellular repeaters.
Research & Network Planning: To validate network coverage models, we provide high-precision reference filters for measurement gateways to determine actual link quality without external spectral contamination.

Suitable Filter Categories for Wireless Connectivity & IoT / LoRaWAN

Requirements for spectral purity in the sub-GHz range demand filter solutions that combine exceptionally high quality factors with minimal insertion loss.

Band Pass Filters

Our LoRaWAN Band Pass filters provide precise selection for ISM bands at 868 MHz and 915 MHz. They are specifically optimized for use in professional outdoor gateways, featuring extremely steep rejection skirts to safely block the adjacent LTE spectrum below 862 MHz. By minimizing insertion loss, these filters directly support system link budget, as every decibel of loss avoidance can increase coverage by hundreds of meters. The mechanical stability of our resonators ensures that the filter curve remains absolutely stable even under extreme temperature fluctuations at mast locations. Manufacturers of infrastructure components benefit from the high power handling and long-term stability of our filters.

Manually Tunable Band Pass Filters

For the development of LoRa modules and gateway prototypes, we offer manually tunable Band Pass filters covering the entire range from 400 MHz to 1000 MHz. Via high-precision mechanical tuning elements, the center frequency can be adjusted exactly to regional LoRaWAN channels (e.g., EU868, US915, or AS923). This flexibility allows engineers to validate the immunity of their designs against specific local frequency allocations in the lab. The robust construction guarantees permanent reproducibility of the filter curve, which is indispensable for consistent measurement results during product certification and field tests.

Digitally Tunable Band Pass Filters

Electronically controllable filters support modern SDR-based gateways that must react agilely to various frequency plans. Via digital interfaces such as SPI, filter parameters can be adjusted in real-time, which is particularly advantageous for devices that switch dynamically between channels or support different regional standards. Our digitally tunable filters combine digital control precision with the necessary RF quality and are optimized for use in test environments and development systems. They enable rapid reconfiguration of automated test rigs without manual hardware swaps, supporting efficient quality assurance processes in the manufacturing of IoT hubs.

Band Reject Filters / Notch Filters

Our LoRaWAN notch filters serve to eliminate specific interfering signals, such as from a directly adjacent LTE 800 transmitter, which could impair gateway sensitivity. They feature extremely deep stopband attenuation of often over 50 dB, while the LoRaWAN passband remains nearly unaffected. This protection is fundamental for maintaining Quality of Service (QoS) at co-located sites with cellular towers. By using our notch filters, the robustness of the infrastructure against strong out-of-band signals is massively increased, significantly reducing packet error rates.

Manually Tunable Band Reject Filters / Notch Filters

Frequency-tunable notch filters provide field technicians with a quick solution for suppressing unforeseen interference in the sub-GHz range. By manually adjusting the stopband frequency, interfering signals caused, for example, by poorly performing industrial radio systems in the vicinity can be masked immediately. This ensures the availability of critical LoRaWAN networks without waiting for new hardware components. The mechanical precision of our filters guarantees that once a stopband frequency is found, it remains exactly maintained over long periods, even under vibration at mast locations.

Digitally Tunable Band Reject Filters / Notch Filters

In intelligent IoT networks, digitally tunable notch filters enable an automated response to dynamic interference scenarios. Controlled by monitoring algorithms, these filters can dynamically mask interfering signals in real-time to maintain Quality of Service for critical applications such as smart grid controls. Their integration into automation concepts for radio optimization allows for autonomous radio optimization across entire city areas. Thanks to remote controllability, operators can adjust filter characteristics centrally, reducing operating costs and massively increasing the resilience of LoRaWAN nodes against new interference sources at shared antenna sites.

Monoplexer / Diplexer / Duplexer / Triplexer

Separating transmit and receive paths at a LoRaWAN gateway requires high-performance duplexers with extremely high isolation. Our solutions for the 868 MHz band are optimized for highest power handling combined with minimal PIM to prevent the device's own transmitter from blocking the high-sensitivity receiver path. Triplexer solutions are used when LoRaWAN must be combined with other services such as LTE-M or NB-IoT on a shared antenna. Wainwright Instruments manufactures these components with the highest precision to ensure that multi-mode gateways develop their full performance across all utilized frequency ranges. Our multiplexers are optimized for use in professional gateways and industrial infrastructure applications.

Absorptive Filters

Absorptive filters play a crucial role in the transmission infrastructure of LoRaWAN gateways to protect amplifier linearity and effectively eliminate harmonics. Rather than reflecting unwanted harmonics back to the power amplifier, these filters safely convert them into heat, preventing reflection damage. This is particularly important for complying with strict regulatory emission limits (ETSI/FCC) in crowded radio fields. Our absorptive filters are designed for continuous operation and increase hardware lifespan by consistently minimizing thermal stress from reflected energy and significantly improving signal purity.