In article ,
Jules wrote:

Me wrote:

The basic facts a Any commercial civilian Xband Radar will NOT even
come close to approching FCC RF Radiation Biologic Health Maximum
Radiation Power Densities even if you are right next to the antenna.
You are more likely to get hurt by the rotating antenna hiting you
in the head than from the RF Energy coming out of the antenna.
Wx Radar on Commecrcial Aircraft usually are left in Standby Mode
untill the aircraft has taxied onto the tarmac beside the active runway.
runway
Eve if they were activated, most xBand versions still don't have the
Power Density one foot in front of the antenna to approch the FCC RF
Radiation Biologic Health Maximum.
Military Radars are a totally different beast altogether, and there are
very strict operational rules for when they can be operated inside US
Water and Airspace.

On my plane the radar is 7.6 kw (xband). The manual says not to use it
on the ground especially around people. Also they have been know to
cause some sort of sparking on metal so fuel trucks are to be avoided.
Shop people are cautioned to make sure it is not emitting if in stby
mode, some do. The display will say STBY, the antenna not panning, but
it is emitting. Go figure. Small airplanes have xband not because it is
wimpy but because of antenna size constraints. These are 10 ro 12 inch
diameter "flat dish" antennas. Lots of waveguide-like openings on it.
Extreemly directional. And this is a small 6 seater plane.

Large weather radars, ground based are sband. Big antennas.

In the late 80's many radars dropped down to under 10 watts. Most under
one watt. Mainly due to improved signal processing. Even on large jets
with large dishes. With the lower power came more managable attenuation
affects in rain too.

You do not want your head one foot away from my radar when it is on. And
I wouln't let you try it, even if you asked.




Jules, you really need to go back to Radar School and try and understand
the technology that your using. 7.6Kw Pulsed Xband Radars have an AVERAGE
Power of less than 20 watts. It isn't the Peak Pulse Power that fries
you, or causes the sparks, it is the AVERAGE Power, and less than 20
watts one foot in front of ANY antenna is considerably less than that,
due to RF Radiation being subject to the Inverse Square Law. Most of
the old Decca 20Kw Commercial Marine Radars in xBand had Average Powers
less that 35 watts, and were well below maximum Radiation Power
Densities directly in from of the 6ft Slotline Antennas.
Your socalled Flat Dish antennas at nothing more than a tuned Phase
Array, and again, one foot out in front, Power Densities are well
below maximum permissable Power Densities.

Third Generation Commercial xBand Radar Technology, that came in the
80's, introduced Solid State LNA's, Ring Circulating Isolators, and
Logrythemic IF ampilfiers, which improved the receivers Noise Figures,
and Dynamic Gain by an Order of Magnitude. This is all in the RF Path,
and had nothing to do with signal processing of baseband signals which
didn't come into play untill DSP Processors were intoduced in the mid
90's and the Fourth Generation of Commercial Radars.

Manuals are written by folks who understand the technology, about as
much as the lawyers, that approve them before they are published. Yes,
there are safety concerns with radar operations around FBO Fueling
Operations, but the incidents of actual causal problems, are rare to the
extreme.

Again, all the above is TRUE only for commercial radars, and may, or may
not be TRUE, and likely NOT TRUE for Military Radars, as these are more
often than not CW operating, and, or doppler type radars that are NOT
Pulsed.

Me

Me wrote:
7.6Kw Pulsed Xband Radars have an AVERAGE
Power of less than 20 watts.

I know it works in pulses and it is the pulse you should look out for.
Like a microwave oven , it can induce voltages in pieces of metal, high
enough to cause sparks. What would that do to a person with a pacemaker?

I only know the power rating.
I am not sure arcing incidents are that rare as I have met a couple of
people who claim to have seen it happen.

If a hammer drops on your foot and then rests there for 20 minutes, is
it the pulse or the average force to look out for.

My radar...

Peak Power Output: 7.5 KW nominal, 6.0 KW minimum

Output Frequency: 9375 Mhz (X-Band)

I think it does 160 pulses per second.



You would be willing to take the full brunt of that one foot away? I
will be back at the airport this afternoon and ask for someone to hold
thier head up to the radome. I never went to radar school.

I'll take your word for it, but I won't volunteer!

In article ,
The Visitor wrote:

Me wrote:
7.6Kw Pulsed Xband Radars have an AVERAGE
Power of less than 20 watts.

I know it works in pulses and it is the pulse you should look out for.
Like a microwave oven , it can induce voltages in pieces of metal, high
enough to cause sparks. What would that do to a person with a pacemaker?

No, absolutly NOT, Microwave Ovens are NOT pusled, they are CW, and
continious. It is AVERAGE Power that fries you, not Peak Pulse Power.
See, this is what you seem not to understand, about the technology that
is being discussed. You don't seem to have a grasp of how the technolgy
works.


I only know the power rating.
I am not sure arcing incidents are that rare as I have met a couple of
people who claim to have seen it happen.

and I have meet a lot of people that claim to have seen and been
kidnapped by aliens, too......

If a hammer drops on your foot and then rests there for 20 minutes, is
it the pulse or the average force to look out for.

not analogous, at all, and just shows that yoiu don't undertand the
technology that you talking about.


My radar...

Peak Power Output: 7.5 KW nominal, 6.0 KW minimum

Output Frequency: 9375 Mhz (X-Band)

Most likely using a 2J42 Magnitron or equivilent....


I think it does 160 pulses per second.

that seems a bit low, should be in the 500 to 750 range, but ok..

and the Pulse Width, which you don't cite, is the determining factor
in calculating the Average Power of the RF Energy emitted from the
device. Typical Pulse Widths would be in the .1 to 1 microsecond range
for this type of radar. So lets take 1 microsecond.
1 * 160 = 160 microseconds total ON time out of 1000000 microsends/second
160.0/1000000 *7500 Watts Peak Pulse Power = 1.2 Watts Average Power

Now understand that RF Energy is nonIonizing radiation and therefore
interacts with biologics as HEAT. Now just how much heat will be
transfered to you from a 1.2 Watt light bulb held in your hand,
assuming that you get 100% capture of that power into your hand,
and considering that if your standing out in front of the antenna
even at one foot, the Inverse Square Law still applies?




You would be willing to take the full brunt of that one foot away? I
will be back at the airport this afternoon and ask for someone to hold
thier head up to the radome. I never went to radar school.

that is obvious....


I'll take your word for it, but I won't volunteer!

Me