ultrawideband wave radar, the portable high powered x-ray machine.
sees through walls, containers, people...

It suffers the same visibility modifiers as Ultrasound.
At max rating (4) it can see through 20 pts of materials (10cm of contruction ferrocrete is something between 11-13)
It has a signal rating of 2 and can be jammed.

But put that on a scorpion spy drone and it'll make short work of mapping out everything and everyone.

I'm not interested in stopping it, I'm interested in understanding what would detect ultrawideband radar.

If you are standing at a bus stop and in the bushes 20 feet away is a wee scorpion with rating 4 ultrawideband radar.
He's scanning you.

What would make you react? What gear would you need to detect the ultrawideband pings bouncing off your melon?

How much detail is this device detecting, if your using it to monitor movement behind objects might be hard to fool.

Any sensor capable of detecting the wavelength band would pick it up pretty quickly.

Could fool it or a at least lessen its usefulness by producing "noise" on the same wavelength bands sensor is using.

Rules pretty generalized but Jammer might affect it?
Signal masking would work but seems to be limited to vehicles.
Unless you allow signal masking materials to be applied to armor?

Signal Masking is How we did it in 4th... But it was pretty expensive to apply to body armor (and it needed to be full Body Armor for it to work properly.
Not many players went to the extremes of protecting against the UWR due to price of the Masking.

I'm assuming by "ultrawideband radar" you are talking about the (terahertz) Radar Sensor from CF, because the stats you mentioned fit:
- "Radar pulses are detectable by any wireless device, but most won’t be able to identify them as anything more than background noise" (CF p. 81). So you'd have to configure your commlink to specifically listen for it -- call it "sensor mode" and handle it the same as running silent
- Your own Radar Sensor, obviously
- With SR technology, a THZ detector which only registers signal peaks should be cheap as an infrared sensor is today, how about RFIDs with a tiny OLED that lights up when touched by pulsed T-ray?

Sounds to me like he is describing the Ultrawideband Radar and the Radar Sensor cyberware from 4th ed Arsenal and Augmentation respectively.
If this is the case, remember it sees textures and movement, not color or other details. So while it may know a person is there, it can't really tell you who they are unless there is something distinctive about their shape. Like you could tell if it was a troll or an ork but unless that troll has a particularly distinctive horn curl or something, you can't tell who it is without some other cues. If you knew what cyberware the troll was packing, you could use that to help with the ID (it can detect cyberware).
Its 2 signal gives it a pretty good range to detect things but a signal of 2 is also very easy to jam. Directional jammers are a good choice here. While it is able to see through a lot of things, figuring out just what you are looking at in a crowded situation is probably going to require a good perception test on the part of the observer (and if you are just using the sensor then your intuition is replaced by the sensor rating). Wireless negating paint and Faraday cages don't play well with the sensor either.

Mantis is on the money.

In terms of stopping it I'm with you. Faraday, Wifi negating paint, jammers... all solid stationary defenses.

I was more concerned with the average team of runners and or corp sec out on the town... how would they know they are being scanned by ultrawideband?

an RFID that is programmed to respond to ultrawideband would work but it's a very custom solution where I was looking for what was out there "out of the box"

Any drone of vehicle having it's own radar could detect the ultrawideband scan but I seem to recall it isn't easy and usually appears as background noise... I'll look into that.

Well I wonder why they would care they were being scanned if they were just out on the town. They probably pass by a million cameras, MAD scanners and other sensors in their day to day life. Do they worry about them all? Probably not.

If they are on the job, then a perception test should give them a chance to spot the drone. They can also do a matrix scan for hidden nodes in the area to try and find the thing. Jammers are likely to be in use at this point as are other anti scanner tech. Their hacker will also be on the job, checking for exactly this sort of thing.
A corp could use telematics software to tell when something is in the area that doesn't belong, like the drone you mention. This of course won't work out on the street very well but in a facility of some sort it can be very effective at keeping out or at least spotting unwanted spies.

On the magic front, while Improved Invisibility won't help, a Physical Mask spell may help as can spells like Chaff.

My point with these solutions is, if they are concerned with being spied upon, the type of sensor is less important than the fact they are being observed. If they don't know that basic fact it won't matter what solution they have to counteract it.

I can't wait for Shadowrun to catch up with actual science and start introducing Femto-Photography to look around corners using virtually undetectedable light sources (its shining a visible spectrum laser onto a surface for femtoseconds* at a time). Although I'm unsure what a second femto-camera aimed at the first would see (aside from the obvious "what's around the corner in the hallway?" answer: "another femto-camera").

*For reference, a femtosecond is 1/1,000,000th of a nanosecond, which is 1/1,000,000th of a milisecond. That works out to 1/1,000,000,000,000,000th (1 quadrillionth) of a second!

Damn, looks like they just copied over the stats. The part about wireless devices considering it background noise is from Chrome Flesh, however...as is the part about wireless devices being able to receive the signal in the first place, so no real change.

Neither 4th nor 5th say anything about T-Ray/UWB systems not being able to receive another system's signals, so I would say apply common sense: If it can receive its own return signal, it can also receive signals from other systems working in the same frequency range. And this should work at longer ranges than the imaging, because the signal does not have to make the return leg to the original sender and the signal doesn't even have to be strong enough to produce an image, just enough to be recognizable as a signal.

So the solution straight out of the box is to get your own, at R 1 in a portable sensor box coupled to your commlink

Kinda wished they had just simplified sensors and called them either passive or active. All this extra detail about different sensor suites not following through with their passive equivalents or at least saying an active sensor (radar for eg.) is also a passive sensor for other radar systems is cumbersome. Or at least out right stating that active sensors are also frequently passive sensors for the same type so those of us who don't have in depth knowledge of sensor systems don't have to ask questions like this. Oh well, I can dream.

Well, it does explicitly say so for ultrasound. Of course, that can either be seen as a precedent, or the fact that this statement is missing for all other sensors can be seen that ultrasound is an exception. A simple (a) or (p) behind each sensor sounds like a good idea indeed.