Why do automotive radar devices work only in 24 and 77-79 Ghz bands?

Question

Commercial Automotive RADAR devices work on frequencies of 24 Ghz and 77 - 79 Ghz.

My question is only these frequency bands ? Why not say 40 Ghz ? What's so special about 24 Ghz and 77-79 GHz that commercial RADAR based Collision devices are available only in these bands ?

You can not just willy nilly bring a product onto the market in any specific frequency that you like — PlasmaHH, Jul 04 '16 at 15:03
The International Telecommunication Union co-ordinates worldwide spectrum allocation and usage. Governments enforce legislation to ensure conformity with the rules. — Chu, Jul 04 '16 at 15:32

score 1 · Answer 1 · answered Jul 04 '16 at 17:48

From around 55 to 65 GHz, there is a strong absorption band due to oxygen in the atmosphere. This area may not really be usable. The peak is around 15 dB/km. But the rest of the region from 24 to 79 GHz seems like it would be usable apart from government regulations.

The manufacturers probably do not want to use different bands in every country, so if a spectrum area is not available in just one important market, they will probably avoid it in all markets. Not sure if that has an effect in this case, but it can in other areas.

Why do automotive radar devices work only in 24 and 77-79 Ghz bands?

1 Answers1