[Elecraft] how did I calculate the loss?

[Stuart Rohre]

I would imagine the line length of a parallel line end fed doublet would
affect the imbalance as well.

If one has the whole antenna well up in the clear, the feeder radiation and
pick up might not detract from your operation.  If in a high noise area, I
would be concerned.

Center fed antennas are so much better behaved, it is the best way to go
when the new ham is starting out; and I try to dissuade them from using a
single wire in our area here which has NO good RF ground available.  YMMV in
you live in wet north, seaside, etc.  Counterpoise wire is a necessity here
unless one has a balanced antenna.  Plus, if you put all your RF into the
air, you know it is doing more good than warming the worms.
-Stuart
K5KVH