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