VE COM Antenna

[spg_76013]

Hi All -

 

My VariEze wing/winglets are complete but not painted. Years ago I failed to install a COM antenna inside the winglets, as I should have. C'est la vie.

 

I realize it might be too late to do so, but figured I'd ask anyway: does anyone have any advice/lessons-learned about installing a COM antenna on a VE winglet at this stage? I've got conduit access at the bottom of the winglet, about mid-chord. Could/should I install the antenna part of the "V" 1/2 way up the winglet, with the ground-plane part of the "V" along the lower surface of the wing, or is that a plain bad idea?

 

Follow-up question: If a winglet-install of a COM at this stage is not a good option, what is the next-best spot, in y'alls opinion? Underside of gear legs? Fuselage sidewall?

 

Any advice appreciated.

 

Sean Gillen

Arlington, Tx

[JTest]

G'day

 

I just got my latest issue Central States (July 08); it has an article for the install on the back of the pilot seat and up the headrest. You may wish to check it out.

 

Good luck;

 

Jeff

[Spodman]

When you say 'complete but not painted' what stage of the finishing process are they at. Would it be possible to put the antenna over the current finish, put a tape over it and then re-fill, (unless you haven't yet)?

[TMann]

You can do most anythig ...... it's just a matter of how far you're willing to go.

 

If you're real determined, sand the outside of the winglet down to the glass then either lay the foil on the glass and micro over or.....

Cut out a section of glass, put in your antenna and micro, glass, micro OR .........

What I would suggest, put in an external antenna and get the bird flying.

 

The downside of trying to put an antenna on the back of a seat or inside the sidewall is it's too close to the sacks of saltwater you're hauling (Pilot & Passenger)

[Lynn Erickson]

Hi All -

 

My VariEze wing/winglets are complete but not painted. Years ago I failed to install a COM antenna inside the winglets, as I should have. C'est la vie.

 

I realize it might be too late to do so, but figured I'd ask anyway: does anyone have any advice/lessons-learned about installing a COM antenna on a VE winglet at this stage? I've got conduit access at the bottom of the winglet, about mid-chord. Could/should I install the antenna part of the "V" 1/2 way up the winglet, with the ground-plane part of the "V" along the lower surface of the wing, or is that a plain bad idea?

 

Follow-up question: If a winglet-install of a COM at this stage is not a good option, what is the next-best spot, in y'alls opinion? Underside of gear legs? Fuselage sidewall?

 

Any advice appreciated.

 

Sean Gillen

Arlington, Tx

you could put the copper foil type antenna on the surface and a layer of tape over it or do as I have on many canards. use copper tube about 3/16" diameter or 14 gauge solid copper wire. insert it in the foam winglet by pushing it upward into the foam for the vertical leg 20.3" long and one in the wing foam for the horizontal leg also 20.3" long connect the shield conductor of the antenna wire to the horizontal leg and the center conductor to the vertical leg. put three torroids on the wire just as in the foil type antenna. many will say both of the legs should be vertical and they would not be wrong. many will say that the thin wire will narrow the band with and they would not be wrong. and I would say just do it this way, it works great. its not perfect some days I have had a little trouble hearing Denver center from So. Cal. but as soon as I get to the Colorado river they are load and clear

[argoldman]

If you are not painted, I vote for the antenna and tape on the outside.

 

The problem with a 14 Ga wire, or any thin antenna is the following:

 

An antenna is tuned (by length) at only one specific frequency. as you go higher or lower, the efficiency drops off. Now, the wider you can make your antenna, ie with copper tape, the more frequencies will be in "tune" with your antenna. Using a thin wire, some freqs will be great and the rest will suffer.

 

That being said, you may never know the difference unless you compare it with another antenna type.

[Lynn Erickson]

If you are not painted, I vote for the antenna and tape on the outside.

 

The problem with a 14 Ga wire, or any thin antenna is the following:

 

An antenna is tuned (by length) at only one specific frequency. as you go higher or lower, the efficiency drops off. Now, the wider you can make your antenna, ie with copper tape, the more frequencies will be in "tune" with your antenna. Using a thin wire, some freqs will be great and the rest will suffer.

 

That being said, you may never know the difference unless you compare it with another antenna type.

I do have one argument to this, then why are standard certified com antennas made out of thin stainless wire

[Waiter]

A 1/2 inch foil with the ends cut at a very sharp angle will have a lower VSWR (Voltage Standing Wave ration) over a wider range of frequencies than the same 1/2 inch foil with the ends cut at a 90 degree angle (or a piece of wire)

 

A VSWR of 2.0 is acceptable with todays electronics, but a 1.0 is always the goal.

 

Measuring the VSWR of two antennas (a sharp foil and a straight wire) at three points, 118 Mhz, 127Mhz, and 136Mhz should result in readings similiar to these:

 

Foil with very sharp cutoff centered at 127 Mhz:

1.5, 1.2, 1.5

 

Piece of wire centered at 127 Mhz

1.7, 1.2, 1.7

 

 

Both antennas are acceptable, the foil would have a lower "Q" (technical term used to define the 3db points of the frequency response) compared to the wire.

 

Waiter

[argoldman]

I do have one argument to this, then why are standard certified com antennas made out of thin stainless wire

Lynn,

 

And we used to use long wires from the tail to somewhere on the top of the cabin for ADF before someone discovered there was a better way to do it (these antennas are still certified). (Of course, progress all but obsoleted the ADF). If you dissect a modern com antennae, I believe that you will find that it is a foil strip wrapped in a sleeve.

 

Don't forget that requirements or approvals are based on minimum acceptable performance---- in every field:o