In a message dated 1/24/2009 3:13:23 A.M. Eastern Standard Time,
europa-list@matronics.com writes:
>>>> I'm planning on running a tail light/tail strobe at the highest
point on the rudder trailing edge; will these wires (running down the
back side of the stern post) create electronic interference if I were
to adopt your antenna solution?.<<<<
Hey Fred,
The way to make a highly directional antenna out of a dipole is to put a
metallic object parallel and in close proximity to the antennas elements. I
would avoid putting any metallic objects, particularly along the entire length
of
the antenna elements, that are within 2 wave lengths distance from the
antenna. If you do this you will likely change the radiation pattern of the
antenna considerably and you risk having blind spots, along with poor transmit
and
receive characteristics. The two wave length distance is a general rule of
thumb. Whether or not your strobe wiring will interfere also depends on your
radio's noise rejection characteristics. Noise rejection characteristics vary
---From radio to radio and manufacturer to manufacturer, but one thing is
certain. Aircraft Com radios are AM and that does not bode well for noise
rejection
at all, regardless of who made it. I would try to keep your strobe wiring and
the light itself as far away as possible from antennas and audio wiring and
be sure to ground the strobe shield wire on one end, preferably to the case
of the strobe power supply, such as under one of the mounting bolts so that
the shield wire contacts the case of the strobe power supply.
>>>>..what about the same if I were to
install the Bob Archer in the fin?...or should I move the BA forward
of the rear bulkhead to where there would be adequate height within
the fuselage shell?<<<<<
Consider antenna accessibility if you are thinking of placing it inside the
vertical fin. There might come a time at some point in the future where you
will need to get at it. This isn't likely, but it would be my luck if I were
to place an antenna in an inaccessible area I would have to get to it for some
reason. I would think that would result in major surgery if you install it
inside the fin above the bottom rib. One of the reasons why I put my AAE Com
antenna on the back side of the stern post was for accessibility. For
installation forward of the rear bulkhead, again you have to consider the
metallic
objects that are in close proximity, i.e., elevator push/pull tube, elevator
mass balance, etc. One solution might be to install your Com antenna right
behind the "D" panel in the baggage bay bulkhead. You're only radiating about
5-8
watts with the Com, so there isn't much of an RF hazard to consider. The
transponder antenna is one I would want as far away as possible from me, audio
wiring, and other electronics that might be sensitive. Some transponders pulse
as high as 250 watts ERP. 1090 Mhz at that power level is certainly
something to consider.
Hope it helps!
Regards,
John Lawton
Whitwell, TN (TN89)
N245E - Flying
**************A Good Credit Score is 700 or Above. See yours in just 2 easy
steps!
cemailfooterNO62)
|