Overview
The Industrial, Scientific, and Medical (ISM) bands in Australia are defined in the Australian Radiofrequency Spectrum Plan (ARSP 2025), maintained by the Australian Communications and Media Authority (ACMA). These are frequency ranges available for shared, license-exempt use — primarily for non-communication applications, but widely repurposed by modern communication systems such as Wi-Fi, Bluetooth, LoRaWAN, and RFID.
Operating in ISM bands in Australia means adhering to class-licence conditions, EIRP limits, and emission constraints. Devices must accept interference and not cause harmful interference to licensed services.
Australian ISM Bands (per ARSP 2025)
| Frequency Range (MHz) | Typical Applications | Max EIRP / Power Limit | Key Technical Notes |
| 6.765 – 6.795 | Induction heating, RF welding | 42 dBµA/m @ 30 m | Narrowband industrial energy applications; interference mitigation required. |
| 13.553 – 13.567 | RFID (13.56 MHz NFC), contactless cards | 60 dBµA/m @ 10 m | Very short-range, magnetic-coupled; heavily used for ISO 14443 / ISO 15693. |
| 26.957 – 27.283 | Industrial control, RC, telemetry | ≤ 1 W EIRP | Shared with LIPD devices; 27 MHz CB channels adjacent. |
| 40.66 – 40.70 | Low-power telemetry, motion sensors | ≤ 25 mW EIRP | Short-range; used in industrial control and keyless entry. |
| 433.05 – 434.79 | Short-range devices, garage doors, telemetry | ≤ 25 mW EIRP | Popular SRD band; shared with EU ISM allocations; potential congestion in urban areas. |
| 902 – 928 (AU 915 MHz subset) | IoT / LPWAN (LoRa, Sigfox), telemetry | ≤ 1 W EIRP (typically ≤ 30 dBm EIRP under class licence) | Primary LPWAN band in AU; ensure compliance with AU915 plan (915-928 MHz only). |
| 2 400 – 2 500 | Wi-Fi 2.4 GHz, Bluetooth, ZigBee | ≤ 4 W EIRP (point-to-multipoint) | High congestion; robust coexistence design needed. |
| 5 725 – 5 875 | Wi-Fi 5 GHz, microwave links | ≤ 4 W EIRP (outdoor fixed), ≤ 1 W EIRP (portable) | High data-rate capable, but higher path loss; DFS/TPC often required. |
| 24 000 – 24 250 | Industrial radar, short-range sensors | ≤ 100 mW EIRP | Millimetre-wave applications; high attenuation and short range. |
| 61 000 – 61 500 | mmWave data links | ≤ 500 mW EIRP | Very short range; atmospheric loss dominant. |
| 122 – 123 GHz / 244 – 246 GHz | Experimental, imaging, sensing | ≤ 100 mW EIRP | Emerging for imaging, motion sensing, and high-bandwidth data. |
Reference: ACMA — Australian Radiofrequency Spectrum Plan 2025
Power & Emission Constraints
The Radiocommunications (Low Interference Potential Devices) Class Licence 2015, as amended, defines emission limits, modulation requirements, and power constraints for each ISM range:
- 902–928 MHz:
- Up to 30 dBm EIRP for spread-spectrum or frequency-hopping systems (LoRaWAN, DSSS, FHSS).
- Duty cycle restrictions may apply depending on modulation and channelization.
- 2.4 GHz & 5.8 GHz:
- Max 4 W EIRP for outdoor fixed links (e.g., PTP Wi-Fi bridges).
- Portable/indoor typically ≤ 1 W EIRP.
- DFS/TPC required in certain sub-bands to protect radar and satellite links.
- 433 MHz & 27 MHz bands:
- Low-duty cycle transmitters only, ≤ 25 mW EIRP.
- Ideal for SRD, remote keyless entry, and telemetry.
- 24 GHz & above:
- Radiated limits much stricter due to propagation loss; typically ≤ 100 mW EIRP.
- Mainly used for automotive radar, industrial level sensing, and motion detectors.
Key Engineering Implications
1. Band Selection
- 915 MHz: Best for IoT and LPWAN (LoRaWAN, Sigfox, proprietary). Good range and penetration; verify AU915 channel mask.
- 2.4 GHz: Universally supported hardware; heavy coexistence burden.
- 5.8 GHz: Shorter range but cleaner channels; high data rates for point-to-point.
- 24 GHz+: Ideal for radar/imaging, but high loss requires directive antennas.
2. Coexistence Design
Given ISM bands are shared, design must incorporate:
- Spread spectrum (FHSS, DSSS, CSS)
- Forward error correction and adaptive data rate (ADR)
- Clear channel assessment (CCA) and backoff schemes
- Channel agility to mitigate congestion
3. Antenna & Propagation
| Band | λ (Wavelength) | Propagation traits |
| 433 MHz | ~69 cm | Long range, robust through walls |
| 915 MHz | ~33 cm | Balanced range/antenna size |
| 2.4 GHz | ~12.5 cm | Moderate range, small antenna |
| 5.8 GHz | ~5 cm | Line-of-sight, poor penetration |
| 24 GHz | ~1.25 cm | LOS only, high path loss |
4. Certification
Before market entry, devices must:
- Comply with ACMA EMC & RF standards (e.g., AS/NZS CISPR 11, ETSI EN 300 220/328 equivalents).
- Bear RCM (Regulatory Compliance Mark) demonstrating conformity.
- Operate strictly within the class-licensed EIRP and frequency limits.
Example: IoT Deployment in AU915 MHz
For LoRaWAN deployments:
- Band: 915–928 MHz
- Spreading factors: SF7–SF12 (CSS modulation)
- Max EIRP: 30 dBm (with 2 dBi antenna typically)
- Channel plan: 8 uplink channels (915.2–916.9 MHz), 1 downlink (923.3–927.5 MHz) per AU915 standard.
- ADR: Must adjust data rate to minimize time-on-air and comply with duty cycle.
Summary
- Australia aligns broadly with ITU Region 3 for ISM allocations but enforces local power, duty-cycle, and emission limits.
- The main ISM bands—13.56 MHz, 27 MHz, 433 MHz, 915 MHz, 2.4 GHz, 5.8 GHz, and 24 GHz—cover everything from RFID to mmWave radar.
- Designers must ensure compliance with ACMA’s class-licence conditions and RCM certification.
- Successful ISM deployment requires careful trade-off between range, throughput, coexistence, and regulatory limits.
References:
- ACMA. Australian Radiofrequency Spectrum Plan 2025
- ACMA. Radiocommunications (Low Interference Potential Devices) Class Licence 2015
- ITU-R. Radio Regulations, Edition 2024