ISM Bands
ISM Bands (or Industrial-, Scientific- or Medical Frequency Bands) are attractive frequency ranges for the deployment of Radar equipment. Choosing a frequency in one of those bands reduces the effort to meet necessary regulations. The ISM frequency bands of interest for Silicon Radar products are situated in the range of 24 GHz, 60 GHz, 122 GHz, and 244 GHz. The exact frequency bands are depicted in Table 1. Indifference to the common belief, some parts of these ISM bands still require licensing. More details can be found in the corresponding standardization bodies and documentations. Also, pay attention to national differences which may apply to broader frequency range allocations. In the end, each operator is held responsible to respect these limits when operating radar devices. This applies as well to the power transmission, which shall not exceed 100 mW Equivalent Isotropic Radiated Power (EIRP) for the four bands indicated.
| Frequency | Frequency Range | Bandwidth | Thereof license free(*1) | License free bandwidth(*1) |
| 24 GHz | 24.00 - 24.25 GHz | 0.25 GHz | 24.15 - 24.25 GHz | 0.10 GHz |
| 61 GHz | 61.00 - 61.50 GHz | 0.50 GHz | 61.00 - 61.50 GHz | 0.50 GHz |
| 122 GHz | 122.00 - 123.00 GHz(*2) | 1.00 GHz | 122.25 - 123.00 GHz | 0.75 GHz |
| 244 GHz | 244.00 - 246.00 GHz | 2.00 GHz | 244.00 - 246.00 GHz | 2.00 GHz |
(*1) Please check your exact local regulations.
(*2) FCC proposal to extend ISM starting from 116 GHz up to 123 GHz in the US market.
More relaxed regulations apply for tank level probing radar (TLPR) applications, provided the sensor is kept in a closed environment.
| Frequency | Frequency Range | Bandwidth |
| 24 GHz | 24.05 - 27.00 GHz | 2.95 GHz |
| 61 GHz | 57.00 - 64.00 GHz | 7.00 GHz |
| 80 GHz | 75.00 - 85.00 GHz | 10.00 GHz |
Please note country-specific variations for TLPR applications due to differences in regional regulations.
The European Telecommunications Standards Institute (ETSI) and Federal Communications Commission (FCC) also work on a number of new regulations to open further frequency bands for specific applications and operating conditions. As an example please refer to a technical report which shall foster the introduction of a harmonized spectrum for sensor or radiodetermination applications of Short Range Devices (SRD) using UWB technology within the frequency range 120 GHz to 260 GHz, available under https://www.etsi.org/deliver/etsi_tr/103400_103499/103498/01.01.01_60/tr_103498v010101p.pdf. Such initiatives are often available in draft versions and the implementation into regulation still requires approval.
Automotive Radar
As a further example here we refer to the automotive radar frequency domain :
Automotive 24 GHz : The unregulated 24 GHz narrowband (NB) spans 200MHz, from 24.05 GHz to 24.25GHz. The 24GHz Ultra Wide Band (UWB) spans 5GHz, from 21.65GHz to 26.65GHz but will be phased out in 2022 for both, Europe and the USA.
Automotive 77 GHz : The total frequency band spans from 76 GHz to 81 GHz, thereof the automotive Long Range Radar (LRR) band from 76 to 77 GHz and the automotive Short Range Radar (SRR) band from 77 to 81 GHz.
Please note that automotive radar components will require a complete AEC-Q100 certification which may impose a further cost on the components used.
Disclaimer:
The overview above cannot replace individual information and efforts for the release of sensor solutions on the customer side. No warranty is given, errors and omissions excepted.
