Gentlemen - Like many with LIVs, I have the Lancair-provided Bob Archer folded dipole antenna in my vertical stabilizer.  And though it's SWR is admirably low, it's performance is less than wonderful.  Here's an indication of it's performance as originally installed and after a modification that added two additional ground plane elements made (mostly) of conductive paint.  The mod improved performance significantly.

Original installation* performance:  I flew to a point 30 miles from my airport and orbited there at ~10,000 msl.  I tuned in my airport's ATIS and turned off the squelch on the radio connected to the tail antenna so I could hear even weak reception.  When I was flying at right angles to the course to my airport (airport off either wing), I got perfectly readable reception though the signal strength was not strong enough to completely surpress the background hiss.  However, when the plane was pointed directly to or directly away from the airport, I could not detect any ATIS signal at all.

Ground plane mod** performance:  Same experiment but now I get approximately the same perfectly readable ATIS reception when I am flying to, from or at right angles to the airport.  Between those four cardinal points, the signal strength is less but the readability is still good enough to copy the ATIS in one pass.

This is a big improvement for me as a common time to use COM2 is when I'm nearing my destination and need their weather.   ...Clark Still (LIVPT N750S, KPOU)

Original installation:  Pretty much as described in the manual but I did position the coax attachment point to the antenna close enough to the vertical access panels to be reached.  This resulted in a less vertical arrangement of the ground side of the antenna (the lower side, connected to the shield of the coax) and likely had something to do with the high directional sensitivity of my antenna.  So, be sure you have a directional problem like I did before considering the mod.

The mod:  Basically, I attached two 23" conductors (new ground planes) to the shield side of the coax at the antenna attachment point and mounted them along the inboard right and left, lower trailing edges of the horizontal stabilizer.  I had Brad Simmons (Airframes, Inc, Milan, TN) paint 14" strips of conductive paint along both inboard, lower trailing edges of horizontal and then connected them using 9" wires (conductive epoxy to the painted ground planes) to the antenna.  He then painted the color coats over the conductive paint so the mod is invisible.  If you'd like to test this mod on your plane and can get at the antenna cable or tail antenna connection point, try connecting the shield side of the coax to a couple of ~12" lengths of copper foil tape firmly adhered to the inboard, lower trailing edge (outside) of your horizontal stabilizer.  You may have to adjust the lengths for the best result (in principle, the total length of the wire + conductive strip should be ~23").

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