MYTH or FICTION

Oughta be easy enough to test. Stick a 2.4GHz horn antenna on the input of your spectrum analyzer. Turn the attenuation to zero. Put a similar horn on the magnetron of your microwave oven. Put them a meter apart and pointed at each other. Flip the switch. Report back.

I wasn't there myself but have seen the aftermath and believe the guys who dunnit: BIG pulsed radar on rooftop, guys testing their stuff at other end of roof. Big pulsed radar was turned back on when guys were off the roof, big dish starts to turn again ... *PHUT* ... no more semiconductin' left in the input amp. Don't remember the distance but it was several meters.

I recall hearing of an orbiting communications satellite having its output power amplifier destroyed during commissioning tests due to excessive up link power.

Well, if a pulsed megawatt maggie can literally fry a person to death at 5 feet, then receiver front-end burnout is certainly possible and probably has happened many times.

FFFfffrapppP!

I've had HIGH power radar affect electronics (not just front ends) at distances of over a thousand meters. Not destroy anything, but cause unintended/improper operation.

There is no way that at one meter these would not have totally fried anything in the window...

(We're talking NORAD radar sets.)

Why not consider the front end to be an antenna and apply the Friis equation? Link:

That should tell you if it's possible, and if so, under what conditions.

-mpm

On a sunny day (Thu, 7 Jan 2010 17:18:07 -0800 (PST)) it happened snipped-for-privacy@uakron.edu wrote in :

There was one amateur radio operator who enjoyed burning converters by pointing his beam at them, 1 kW I think. They got to him IIRC.

Those old RF transistors were very sensitive. Do not remember the frequency. Was in the sixties?

Back in the days of 10GHz CW police speed radar, I had a friend that, anytime he spotted a police radar in operation, he would walk up to the car with his nice shiny aluminum clipboard and blow the mixer diode, then ask the cop for "directions" ;-) ...Jim Thompson

I knew a guy for whom it was very unfortunate. It basically fried his eyes and he was gradually becoming blind. And that was over a long distance as well.

I had the privilege of working under Harold Friis at Bell Labs, Holmdel.

He was one of the greatest leaders able to get the best work from those he supervised. He'd plant a thought in your mind and you'd leave his office thinking it was one of the best things you'd ever conceived.

He had 25 patents himself, but was probably responsible for many more issued to those he inspired.

I was once head of the radar department at a large electronics corporation. We shared the roof with a radar rest range and a "dark tunnel" used by the infra-red department. The head of IR was worried about the proximity to an active radar. I once took a NE-2 neon bulb with its leads cut and bent to act an an antenna into the dark IR range with him. The bulb flashed every time the radar "scanned" it from a few feet away. It took me a lot of time to convince him that there was no health danger!

I love it. A nice low tech solution to a high tech problem.

So how do convert the power level from Friis to a field level at the target?

Steve

Friis is irrelevant. Compute the area over which the power is distributed (don't forget to account for antenna gain. Then convert W/m^2 to V/m (free space impeadance = 376 Ohm).

Vladimir Vassilevsky DSP and Mixed Signal Design Consultant

Thats what I needed to know, thanks.. With a bit of egg on my face as I was just trying to explain to my non techie boss what a horn does....

Thanks, Steve

An old Navy demonstration practice on a ship to show sailors why one should NOT walk in front of microwave dishes, was to put a grapefruit onto the end of a broomstick and hold it out in front of the dish when it gets turned on.

The grapefruit explodes.

The demonstration is over. Back to work. Watch where you are walking.

I wouldn't walk in front of an active RADAR emitter with or without you.

At what average power does the grapefruit explode? Just Curious...

Steve

Well, I once meant some one a few years ago, that got burned 90% of his body working on a 2M watt navy radar unit, changing the bleeder resistors. Some one turned it on. He woke up in a military hospital where he stay for some time. He had skin graphs done and still had to live with severe nerve damage and you can imagine what his skin looked like.

Very smart and interesting navy radio tech. It was hard to talk to him with his eyes and face twitching due to nerve damage!.