RAK Outdoor Cavity Band-Pass Filter for Gateways for LoRaWAN®

What Is a LoRaWAN Cavity Band-Pass Filter?

A LoRaWAN Cavity Band-Pass Filter like the RAK Outdoor Cavity Band-Pass Filter is a hardware component that allows only the desired LoRaWAN frequency band to pass through, while attenuating nearby unwanted signals such as LTE, 5G, radar, or train communication systems.

It uses high-Q resonant cavities to isolate the target band, protecting LoRa gateways from strong external interference. This is particularly important in high-noise, urban, or industrial environments.

The RAK outdoor RF filter for gateways for LoRaWAN is designed to work with the following RAKwireless gateways:

• WisGate Edge Pro RAK7289V2/CV2
• WisGate Edge Prime RAK7240V2/CV2
• WisGate Connect RAK7393 (coming soon)
• And other brand gateways using standard N-Female RF connectors

When to Use a Cavity Band-Pass Filter with a Gateway for LoRaWAN

• Near Cellular Towers – Prevents strong LTE/5G signals (700–900 MHz) from desensitizing the LoRa receiver.
• Industrial Sites – Filters out wideband RF noise from heavy machinery, telemetry, or private radios.
• Smart City Rooftops – Blocks interference from FM radio, TETRA/P25 public safety radios, or WiFi mesh.
• Co-location with Other ISM Devices – Avoids spurious interference from Zigbee, alarms, or SRDs sharing ISM bands.
• Agriculture Near Radar / Military Installations – Protects against high-power pulsed radar signals.
• Dense Gateway Environments – Prevents cross-interference when multiple radios share the same mast.
• Rural Long-Range Towers – Suppresses strong distant broadcast signals (FM, DVB) that raise noise floor.

Key Features of RAK Outdoor Cavity Band-Pass Filter

• >75 dB attenuation outside the passband, effectively suppressing nearby LTE/5G/RF noise
• <2.0–3.2 dB depending on model, minimizing signal degradation
• Fully sealed for rain, snow, dust, and high humidity environments
• Easy integration with existing RF hardware. No adapters needed.
• Supports global LoRa deployments: EU868, US915, CN470, IN865/RU864/AU915/KR920/AS923-1/AS923-2/AS923-3/AS923-4

Key Benefits of RAK Outdoor Cavity Band-Pass Filter

This filter improves network reliability and ensures LoRa signal noise suppression, giving operators clearer signal performance and consistent results in varied deployment environments.

• Reduces troubleshooting caused by unpredictable RF noise
• Improves consistency of network data delivery
• Helps extend useful life of deployed gateways
• Supports planning in mixed urban and industrial landscapes
• LoRa signal noise suppression

Use Case #1: Smart City Gateway Near a Cellular Tower

A municipal IoT team installed LoRa gateways close to mobile base stations. The RAK Outdoor Cavity Band-Pass Filter provided stable reception despite heavy LTE activity, ensuring uninterrupted monitoring of street lighting and traffic sensors.

Use Case #2: Industrial Facility with Heavy Equipment

An energy plant deployed gateways across areas with welding machines and motors. The cavity band-pass industrial LoRa filter solution helped suppress industrial interference, allowing accurate data collection for equipment status and maintenance alerts.

Comparison Table: RAK Outdoor Cavity Band-Pass Filter vs. Generic RF Filters

How to Select the Right Cavity Band-Pass Filter

Choose the appropriate filter model based on your LoRa deployment frequency.

Check the frequency label on your device or consult the regional LoRaWAN specification to select the appropriate model.

For example:

• Use the EU868 LoRaWAN band filter when deploying in Europe.
• Use the US915 LoRa band-pass filter when deploying in the United States.

What’s in the Box

• 1 pc Cavity Bandpass Filter
• 1 pc Coaxial RF Cables for Gateway
• 1 pc Waterproof Tape
• 1 pc PVC Tape
• 2 pc Steel straps (Diameter of 40-135mm)

How to Get Started with RAK Outdoor Cavity Band-Pass Filter

• Overview of RAK Outdoor Cavity Band-Pass Filter
• Datasheet of RAK Outdoor Cavity Band-Pass Filter
• Installation Guide for RAK Outdoor Cavity Band-Pass Filter

Frequently Asked Questions

What is a cavity bandpass filter?

A cavity bandpass filter is an RF component that allows signals within a specific frequency range to pass while blocking unwanted signals outside that range. It uses high-Q resonant cavities to achieve very sharp selectivity, offering strong out-of-band rejection. In LoRaWAN applications, cavity bandpass filters protect gateways from interference caused by nearby LTE, 5G, or industrial noise sources. This ensures more reliable signal reception in dense or noisy environments.

How would you know if your filter is a low-pass, high-pass, or band-pass filter?

You can identify the type of filter by looking at its frequency response. A low-pass filter allows lower frequencies through while attenuating higher ones. A high-pass filter does the opposite, letting only higher frequencies pass. A band-pass filter, such as the RAK cavity filter for gateway for LoRaWAN, passes only a defined range of frequencies and blocks both lower and higher signals. Datasheets or specifications usually indicate the filter’s type and operating band.

Will the filter reduce my communication range?

Insertion loss is less than 2.5 dB, which has minimal impact on real-world link performance. In practice, your LoRaWAN communication range remains largely unaffected, while reliability and data consistency actually improve in noisy RF environments. By suppressing unwanted LTE, 5G, or industrial signals, the filter enhances signal quality and reduces packet loss.

How do I choose the right frequency version?

Select based on the LoRa® band used in your country or region. For example, EU = 868 MHz, US = 915 MHz, CN = 470 MHz. Always check the frequency label on your gateway or follow the regional LoRaWAN specification. RAK provides multiple frequency variants so you can match the filter precisely to your network.

Is grounding required?

Yes. We highly recommend grounding the filter to earth using ≥10 AWG wire to protect against lightning and improve ESD safety. Proper grounding not only provides protection against lightning strikes but also enhances electrostatic discharge (ESD) safety for connected devices. This practice reduces the risk of hardware damage, especially in outdoor deployments where storms and static build-up are common.

Can the antenna be mounted directly on the filter?

Yes, the design allows flexibility in how the antenna is connected. You can attach the antenna directly to Port 2 of the filter, creating a compact setup that reduces cable runs. Alternatively, you may use the included coaxial extension cable if your antenna needs to be positioned away from the gateway. Both configurations maintain signal integrity and make the filter easy to integrate into different LoRaWAN deployment scenarios.

Can I use two filters in series?

In extreme interference environments, yes. However, be aware that each filter adds a small insertion loss, so using two will slightly reduce overall signal strength. In most cases, a single RAK Outdoor Cavity Band-Pass Filter provides more than sufficient protection.