Here is how much HP you lose or need at 230 MPH
as a function of drag.

The first column is drag the second is the net HP
out of the prop and the 3rd is what the engine must do
to over come that drag.

The dynamic pressure at 230 MPH is 137.5 pounds per square
foot. An antenna .125 inch in diameter and 18 inches long
has a frontal area of 2.25 sqauare inches or .0156 square foot.
Maybe more depending on the what the base looks like.
Drag will then be about 2.1 pounds with a C sub d of 1.
Half that if the drag factor for round wire is as good as .5.

Let's say it is one pound. That will cost
almost 1 HP.

Paul Lamar