If I mount the radar on the mizzen mast, how much signal will be
blanked by the main mast on a 36 footer?
G

Gordon brought forth on stone tablets:
If I mount the radar on the mizzen mast, how much signal will be
blanked by the main mast on a 36 footer?
G

That's how ours is mounted... It works fine looking forward. But the
view aft is blanked some...

bob
s/v Eolian
Seattle

In article ,
Gordon wrote:

If I mount the radar on the mizzen mast, how much signal will be
blanked by the main mast on a 36 footer?
G

Basically the part of the full circle (angle) it is blocking (maybe add
some of the radar beam width, typically up to 6 degrees for a small
radome) - radar frequencies behave almost like light in that respect.

HTH

Marc

--
Switzerland/Europe
http://www.heusser.com
remove CHEERS and from MERCIAL to get valid e-mail

In article ,
Gordon wrote:

If I mount the radar on the mizzen mast, how much signal will be
blanked by the main mast on a 36 footer?
G

Ok, take a 2X4, and put it at Arms Length, edgewise in front of
your eyes. How much of the Far Field Scenery is blocked by the Wood?
Now move the 2X4 closer, more is blocked but you could still navigate
using your eyes, right? Your Mizzen Mast Radar Mount will be very
similar, in that some of the signal will be reflected by the Mast,
and Shrouds, but the farther it is away from the Radar, the less
will be reflected. Also the Horozontal Beamwidth of your Radar
Antenna will have a Significant Effect on what your Radar can see,
thru the obstucting mast. Narrower Beamwidth, less Reflection,
better Targets, MORE MONEY.

Bruce in alaska
--
add a 2 before @

Gordon wrote in news:13dti6knj5hh173
@corp.supernews.com:

If I mount the radar on the mizzen mast, how much signal will be
blanked by the main mast on a 36 footer?
G


None. The antenna in the little radome is a WIDE piece of printed
circuit board with a phased antenna array cut into it at 10Ghz. As it
sweeps across the main mast and rigging, a return shadow of RF from the
target sweeps across the face of this WIDE phased array, but only cuts
off the return signal to a few elements, never the whole antenna, so you
never miss anything because of the shadow. It sees targets just fine way
further away than you need racing along at 6 knots.

Imagine you are standing at the bow exactly opposite of someone on the
opposite side of the mainmast. Because he is narrow, you can only see
the edges of him on either side of the mast. But, to see what the effect
of the WIDE antenna is, have him hold a linear tube flourescent light
sideways in front of him. The flourescent light tube sticks out both
sides of the mast. The further away from the mast he is, the more of the
light's tube you can see from your side. Look at the boat behind you.
Do you see the shadow of the mast from the light? No, because MOST of
the light's tube is always exposed on either side of the mast. There is
no defined shadow, only a slightly-less-lighted area that's quite wide.
The effect on the radar illuminating the target is very similar from its
wide antenna. It isn't as sensitive as it is to the side pointed through
the mast....but the mast doesn't make a big hole in its coverage, which
is the point. You'll see that big bouy before running it down....(c;

Larry
--
Search youtube for "Depleted Uranium"
The ultimate dirty bomb......

As well, your boat will likely yaw around a bit, like any good sailor
in the groove, chasing every wave and will-o-the-wisp, so like a
compass card, your radar display will wallow around a bit, so even if
your antenna is blanked out a bit to the left, next moment, it'll be
to the right. Some targets will flicker a bit, possibly. Even if the
display doesn't follow the motion of your compass card, it's failings
will. If I wanted to sound lamentably lame, I'd warn: "Don't forget
about the return shadow from your pulpit!" But, The receiver is time
gated, it won't see the blinding glare reflected from the mast (do you
have black tape on your pushpit, to dim the stern light reflection?)
or pulpit and it will see like you can see around the finger upside
your nose, at least until staring at the mast cooks a line on your
cornea. Just 'cause you can't see the radar microwaves doesn't mean
they won't cook you. Do you stare at the sun reflected on windshields,
etc, of cars?

Where are the radar absorbing carbon fiber and U.V. protectant lenses,
glasses and cowlings? Just think! no more worrying about getting a
flying fish in the eye while siezed to the winch knot on your finger,
trying to kick the tranny into reverse, and unhitch your lashed oolau
self steering bungee, while the furler tether snaps and pops out the
giant wind bag into the force five, heeling you so much you float off
from where you were grounded, only to be washed further up on the
rocks before being crushed between the aircraft carrier and the
lighthouse, blinded.

You are still required to keep a lookout.

Old Pav is gone. Now I feel a need to sing, if only poorly. God bless
us, every one!

Terry K