Antennas for aircraft 2

[Higgler]

As an antenna engineer, our company is starting to make antennas for air vehicles. Is anyone out there familiar with some of the requirements for attaching antennas on aircraft,
Example, adding a new Anti-Jam GPS antenna to commercial aircraft is one product that we are producing;

1) Mounting techniques, a)screws with environmental seal, versus b) epoxy resin/glue attachement. Is there normally a cable with a service loop to attach to the antenna before feeding it back in for mounting. Or is blind mate common? What standard connector is most common, type N-female? Are the connectors loctite attached to prevent loosening of the cable attachement?

2) Vibration requirements, I know there is a wide range of requirements depending on location, some general info such as, fuselage of aircraft easy vibration, tail mount is high stress, wings are mid stress, etc.

3) Rain Erosion; testing, I've been involved in some. Is it required for all, or can you cite the material as "good for rain erosion" and skip testing.
Which materials are most common for aircraft mounted antennas. I've used Tefzel and PEEK with proven results, any other common ones. I realize sometimes rain proofing bad materials using a rubber like paint is common, like the forward radomes on commercial aircraft. What is the most common erosion proof paint out there.

4) Air Worthy Certificates, I once worked on a program whereby materials that burn toxic fumes are not allowed on military aircraft, is this true for all aircraft mounted antenna. I assume missiles could use anything, since they tend to burn anyhow. Is there reference material for this.

5) Who are the leading manufacturers of aircraft antennas and radomes to possibly build our hardware?

6) What questions/areas have I overlooked? testability to prove the antenna works? repainting after years of use? structural inspection criteria? Worthiness testing that it doesn't shred apart and enter an engine? Ballpark prices common for a GPS or other antennas? Power required by our antenna - is it easily supplied thru the center conductor of the coax? Overload protection to powerful radars hitting it that might blow out our electronics? EMI/EMC test requirements? Is color important? weight? CG?

I'm full of unknowing, any help would be appreciated,
Thanks,
KCH.

 

[Higgler]

BrianR
For an improved mechanical epoxy resin mounting scheme, the 36 x36 inch layup could be made into 36x1 inch sections (or something like that). Separating the antenna into sections would make it easier to mount to the contour of the skin. Many array designs are naturally layed out in strips like that anyhow.

Would installers prefer to add a separate thicker radome cover over the entiere assembly anyhow? Hence after epoxying the array pieces, a top cover would be added and attached mechanically around the periphery? I was hoping to avoid that through the epoxy resin attachment technique.
kch

 

[BrianR]

A thin antenna attached and sealed around the periphery will be subject to full pressurization loads too, (air through the antenna conector hole - which is not practical to seal). This is in the order of 9 psi plus overpressure margin.

We installed a 5ft satcom antenna and it had an integral radome and flat metal base. It needed an adaptor pedestal to conform to the hull shape and the manufacturers offered machined pedestals for various aircraft but not for this aircraft so our structures people made a fabricated sheet metal pedestal which worked well.

The base of your antenna needs to be able to conform to the hull shape, carry the pressurization load and have sufficient tolerance in its attachment to accommodate fuselage stretching at altitude. Several thoughts come to mind but they are really only appropriate when you're in the design loop.