N200LZ: Chapter 10 - Canard Antenna

[TMann]

I'm just about set up in my basement shop and will be continue my canard work.

Quick question for those who have blazed this trail previously. How many builders have put the foil antenna(s) in their canard?

[Marc Zeitlin]

I'm just about set up in my basement shop and will be continue my canard work.

Quick question for those who have blazed this trail previously. How many builders have put the foil antenna(s) in their canard?

I've got my Marker Beacon Antenna under the lower skin of my canard, centered. The cable exits an inch or two forward of the torque tube.

[Drew Swenson]

On my longez, I put the foil VOR/ILS ant on the bottomside of the canard (epoxy to bottom skin then covered with 1 layer of glass). I put the marker beacon foil antenna along the vert face of the right upper longeron.

[chasingmars]

Apropos of this, I'm going to be skinning my fuselage bottom soon. Is it a reasonable approach to not embed any antennas in the fuselage, and still have sufficient separation, space, etc, using only the lifting surfaces and winglets, assuming a fairly capable full-IFR capability?

 

Marker beacon antenna in the canard, navcoms in the winglet, GPS externals, what else am I missing?

 

Are there drawbacks in orientation of the marker beacon transverse in the canard vice longitudinally in the fuselage?

 

Thanks

[Marc Zeitlin]

... Is it a reasonable approach to not embed any antennas in the fuselage, and still have sufficient separation, space, etc, using only the lifting surfaces and winglets, assuming a fairly capable full-IFR capability?

Yes, although there's no issue with the NAV (or anything else) in the fuselage somewhere.

 

Marker beacon antenna in the canard, navcoms in the winglet, GPS externals, what else am I missing?

There are numerous discussions of antennae placement in the COZY archives. Here's what you need (or should plan for):

 

2 COM - winglets (foil, vertically polarized)

2 NAV - wings/fuselage bottom (foil, horizontally polarized)

1 GS - wing (foil, horizontally polarized)

1 MB - canard/fuselage/wing (foil, polarization not important)

1 Transponder - inside fuselage nose or strake tips - does NOT have to be external (short "whip", aluminum ground plane, vertical)

1 GPS - fuselage nose (per instructions)

1 XM Weather - fuselage nose (per instructions)

1 Strike Finder - strake tips (ask Nick Ugolini)

 

That'll keep you busy for a while.

 

Are there drawbacks in orientation of the marker beacon transverse in the canard vice longitudinally in the fuselage?

No. In theory, the MB should be longitudinal, but since you're always within a few miles of the MB when you're using it, I've been told by antenna engineers that you could use a wet piece of spaghetti oriented any way you'd like and it would work fine. I've never had an issue with my MB antenna reception, and it's transverse in the canard.

[SteveWrightNZ]

Are there drawbacks in orientation of the marker beacon transverse in the canard vice longitudinally in the fuselage?

Yes, but quite likely in theory and not in practice.

 

Here's the theory ;

 

Half-wave center-fed dipole antennas radiate (almost) equally in all directions, except they have a strong null off their tips.

 

Case 1 - If you orient the antenna longitudinally it will have a strong null forward and aft of the aircraft and a strong peak below (and above). This in theory amplifies the effect of "searching the ground for the beacon" because it is hunting for it with a directional antenna.

 

Case 2 - If you orient the antenna crosswise it will have a strong null off its' tips and a strong peak forward and aft, effectively rounding off the "peak" effect as you approach and cross the beacon. (unless you are flying wingtip first)

 

I have not read the beacon system specification but it would logical to me to use a horizontally, forward/aft oriented antenna to maximise the system sensitivity.

 

http://www.google.com/search?q=dipole+radiation+pattern

 

That's the theory - in practice these nulls and peaks just aren't that sharp, and quite likely it would be difficult to tell two installed systems apart. I would go with case 1.

 

With regards to recreationally flying VFR aircraft, I think GPS is much easier.

 

E&OE, YMMV, FWIW, FIIK.

 

S

 

For those who care, I have been involved with radio for thirty years. Had my ham ticket when I was 13 y/o.

[Lynn Erickson]

Yes, but quite likely in theory and not in practice.

 

Here's the theory ;

 

Half-wave center-fed dipole antennas radiate (almost) equally in all directions, except they have a strong null off their tips.

 

Case 1 - If you orient the antenna longitudinally it will have a strong null forward and aft of the aircraft and a strong peak below (and above). This in theory amplifies the effect of "searching the ground for the beacon" because it is hunting for it with a directional antenna.

 

Case 2 - If you orient the antenna crosswise it will have a strong null off its' tips and a strong peak forward and aft, effectively rounding off the "peak" effect as you approach and cross the beacon. (unless you are flying wingtip first)

 

I have not read the beacon system specification but it would logical to me to use a horizontally, forward/aft oriented antenna to maximise the system sensitivity.

 

http://www.google.com/search?q=dipole+radiation+pattern

 

That's the theory - in practice these nulls and peaks just aren't that sharp, and quite likely it would be difficult to tell two installed systems apart. I would go with case 1.

 

With regards to recreationally flying VFR aircraft, I think GPS is much easier.

 

E&OE, YMMV, FWIW, FIIK.

 

S

 

For those who care, I have been involved with radio for thirty years. Had my ham ticket when I was 13 y/o.

that is the theory but my MB is working on a NAV antenna mounted in the canard

[SteveWrightNZ]

that is the theory but my MB is working on a NAV antenna mounted in the canard

Yes indeed, I concur. Much theory is quite worthless alongside practice. For myself, I wouldn't even have a MB, AND I'm not building. Yet.

 

S

[chasingmars]

Here's what you need (or should plan for):

 

Thanks Mark for the summary, that's exactly the sort of thing I was looking for. The archives are great and it's my usual first step, but for some topics, there's not always all that much concensus, and a summary from a flyer is helpful.

 

cheers,

[TMann]

Okay ........ I've got my antennas in and I'm ready to skin the bottom side .......but before I do:

Can someone explain to me why I should wait until AFTER I put my botom skin on before I put in my hardpoints (HD Foam)?

Wouldn't it be more logical to do that now (before I skin ) and shape it to fit the surrounding contour ...... then put my bottom skin on?

[Cozy Girrrl]

If I recall correctly, we skinned one side, we oogered (technical term) the foam out from the other side and put the hard points in , then glassed the other side after sanding the hard points flush (put duct tape on the surrounding foam to protect it before sanding).

No idea which side we glassed first, my guess is it was the bottom since we built a dihedral canard.

Don't ask, we built it bent for the pure hell of it.

...Chrissi

[TMann]

Yeah ..... that's basically the plans method but what I'n saying is why not do the foam inserts before any skin goes no?

That way you can cut all the way through, micro in the hd foam and trim it to the op 7 bottom profile instead of trying to carve out to the glass etc.

[Jason Heath]

Can someone explain to me why I should wait until AFTER I put my botom skin on before I put in my hardpoints (HD Foam)?

No....but some folks might not think that far ahead and the jigs may be under the locations where the hardpoints go which may complicate doing so.

Don't you have full length aluminum strips under you canard? Are they in the way?

[TMann]

Well ...... allrighty then.

I'm going to give this a shot. I'll post pics and either a or a depending on how it goes.

[TMann]

Ohhhhhh ..... way too EZ this way. I tried this on one of the outboard hard points and this method beats the plans method hands down. I'll post pics after the micro cures and I have a chance to sand it to shape.

[JTest]

Ohhhhhh ..... way too EZ this way. I tried this on one of the outboard hard points and this method beats the plans method hands down. I'll post pics after the micro cures and I have a chance to sand it to shape.

G'day Tmann

 

We have been waiting for over 6 months and no pictures....

 

You holding out? Really, I am getting ready to lay-up the canard and I want to get some ideas (if you don't mind).

 

Thanks in advance;

 

JeffT

[TMann]

uhhhhhh............guilty!

I'll get those posted this weekend.

[TMann]

Okay.....I have my camera software reloaded so here's some pics:

1. I mark out the areas where the hard points go and, using a hand held hotwire, cut them out.

2. Using the cut out piece as a template, I traced the shape on the high density foam and then cut it out on the band saw.

3. Micro in place. I left a little excess so I could sand to a perfect fit.

 

Done deal!

[TMann]

I never did post the pic of the high gain antenna install,

I cut off an area of the nose then slt the foam to accept the antenna. A little excavation for the connection and replace the nose.

I put one on each side and the cable exits in the middle od the canard.

[argoldman]

I never did post the pic of the high gain antenna install,

I cut off an area of the nose then slt the foam to accept the antenna. A little excavation for the connection and replace the nose.

I put one on each side and the cable exits in the middle od the canard.

T,

 

It looks good and quite concealed.

 

I was under the impression that a nav horizontally polarized dipole, for max coverage, should have it's legs at less than a 180 degree spread. You may be more directional than you want, but then of course, who uses VOR for VFR any more??

 

Any of you EEs or hams want to chime in.

 

Aunt Tenna

[TMann]

Those are not the copper foil antenna you are used to seeing. I mounted a pair of Advanced Aircraft Electronics high gain antennas in the canard. They call for a straight line mount.

 

If I was doing it over, I would have mounted them under the spar cap. Hopefully that opportunity doesn't come up.