5g and rainfall radar

[beardy]

I may be wrong in my assumptions but :
There are concerns that 5g frequencies could interfere with rainfall radar returns and interpretation. Has anybody in the aviation community assessed this wrt met radar and probably more importantly airborne weather radar and windshear detection. How would you feel about WINDSHEAR warning on approach or departure because the numpty in 24c hasn't got his phone in airplane mode?

[Manwell]

Beardy, I don't know the answer to that one, but it may not require a numpty in the cabin to cause a problem if it is the case. 5G works on millimetre waves, much smaller than previous bands, and that requires stations every couple of hundred metres. If you're flying above them, I wonder if they'll be beaming horizontally only,

I've just spoken to a bloke who has a company in the US involved with 5G, and he reckons it won't. 5G stations radiate mostly horizontally, not omnidirectionally, so that means a cell phone could presumably interfere with Wx radar if it's in the same frequency range. Do you know the frequency of your radar? Apparently Telstra 5G will use 3.5Ghz.

[MickG0105]

This is surely just a Luddite beat up, isn't it? Airborne weather radars are typically X-Band (9.3-9.5 GHz - the Collins WXR-2100 is 9.33 GHz, the Honeywell RDR-4000 is 9.375 GHz) so there's no issue there. Ground based meteorological radars are either S-Band (2.7-2.9 GHz) for very long ranges, C-Band (5.6-5.65 GHz) for ranges of 200 km or so, or X-Band for near range stuff. Apart from the fact that there's no frequency overlap mobile phone tower antennas are tilted down so that they point at the punters carrying their mobile devices. Weather radars on the other hand tend to point up 'cause that's where the weather is.

[beardy]

This is surely just a Luddite beat up, isn't it? Airborne weather radars are typically X-Band (9.3-9.5 GHz - the Collins WXR-2100 is 9.33 GHz, the Honeywell RDR-4000 is 9.375 GHz) so there's no issue there. Ground based meteorological radars are either S-Band (2.7-2.9 GHz) for very long ranges, C-Band (5.6-5.65 GHz) for ranges of 200 km or so, or X-Band for near range stuff. Apart from the fact that there's no frequency overlap mobile phone tower antennas are tilted down so that they point at the punters carrying their mobile devices. Weather radars on the other hand tend to point up 'cause that's where the weather is.
Airborne weather radars tend to point down for most of the cruise and a little up when at lower altitudes.
5g uses a variety of frequencies not necessarily a single one, each region allocating its own range. Some areas have concerns that the higher allocated frequencies will impinge on satellite rainfall radar.
There has already been interference in Hungary with ground based wx radar although not connected with 5g it showed an inadequate consultation process Hungarian radar (https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.itu.int/dms_pub/itu-r/md/09/sem.wmo/c/R09-SEM.WMO-C-0019!!PDF-E.pdf&ved=2ahUKEwju1auO4erjAhVsRxUIHZfoCYwQFjAHegQIBBAB&usg=AOvVaw0Oqi13SoVlgGeVCQIcSc7O)
This is an honest open query about possible overlap with airborne weather radar.

[MickG0105]

This is an honest open query about possible overlap with airborne weather radar.

And the honest answer is that there is no overlap. As I've already said airborne weather radars are X-Band and typically in the 9.3 GHz range. 5G will use two frequency bands; Frequency range 1, which is less than 6 GHz and typically around 3.5 GHz, and Frequency range 2 which is greater than 24 GHz. You'll note that 9.3 GHz is greater than 6 GHz and markedly less than 24 GHz, ie no overlap.

Bear in mind that one of the key issues with 5G is signal attenuation; the effective range between a base station and a device, both specifically designed to exchange data on the 5G spectrum, is measured in hundreds of metres. How anyone thinks that signal is going to be interfering with other devices well off frequency and at considerable distances is anyone's guess.

In any event, all the hoopla to date has been in relation to ground-based weather radar and weather satellite water vapour detection using 23.8 GHz emissions (which is close to the minimum range of 5G FR2).

[beardy]

Thanks for the reply. I'm guessing you are in the USA. Are you confident that there will be no overlap in other parts of the world?

[MickG0105]

Thanks for the reply. I'm guessing you are in the USA. Are you confident that there will be no overlap in other parts of the world?
Nope, Australia.

And yes, given that there are international spectrum guidelines for 5G (it would make life difficult for phone manufacturers if there weren't) I would be relatively confident that 5G will not interfere with airborne weather radar anywhere in the world.

[Manwell]

Mick, since 5G bands are either above or below weather radar, and it's not recommended to stand in front of one in operation, do you know anything about the potential health effects of 5G at either frequency range?

[MickG0105]

Manwell, bearing in mind that we are talking about non-ionising radiation, it's not so much the frequency as the energy that's the health concern. Airborne weather radars like the RDR-4000 are punching out about 900 W; a typical 5G metro-cell (greatest coverage, max power) will max out at about 20 W so we're talking nearly two orders of magnitude difference in power output. Apply the inverse square law to the distances involved (standing directly in front of a 900 W focussed beam transmitter versus being what? 50 - 250 metres from a 20 W transmitter) and you quickly get a sense for the differences.

​​​​​​The analogy that I use frequently is the Sun and your TV - both emit radiation in the visible spectrum and we're rightly counselled not to look directly at the Sun; does that mean that you shouldn't look directly at your TV?

[Jump Complete]

MickG0105. Interesting point, makes sense. A couple of weeks ago, in a Service Station on the M5, above the Urinals was a poster warning of the dangers of 5G. The poster depicted a family on the street, implying they were getting gently microwaved, recalling those old ‘protect and survive’ films from the Seventies about surviving nuclear war.