Just call it "poor" ground. But try them all.

My guess is that it will make very little difference in performance as
calculated by EZNEC whatever you call it.

Horizontal or sloping dipoles are insenstive to what's underneath
them. Radiating efficiency will be in the right ballpark.

The structure, position and height of your house will have a much
greater but indeterminate effect on radiation pattern and you cannot
model your house using EZNEC. Even nearby neighbor's houses will have
some effect. But you will never know what these effects are compared
with the ideal pattern as presented by EZNEC.

Antenna height above what's underneath is the most important
parameter.

In all probability, you will get around and about very well. Many
amateurs do very nicely with even more peculiar antenna systems.
----
Reg.

=====================================

wrote in message
...
What kind of "ground" should I use to EZNEC-model a flat-top dipole
antenna
of which one side will be about 7 feet above and parallel to the
peak of
my house roof and the other half will be about 30 feet above the
yard.

My house is a story-and-a-half (the usual attic was a dormitory for
my
long-gone kids) over a full basement (which just happens to have
both
a Ufer ground in the basement-wall footings and a "ring ground"
around
the outside and at the level of the footings). Thus most of
one-half
of the antenna will be over the usual Kansas soil (about a foot of
fertile
stuff above many feet of more clay-like stuff) while the other half
will
be above the roof above the attic/dormitory above the ground floor
above
the basement above the footings.

So will this be a "good", "bad", "average", or ??? ground for EZNEC-
modeling purposes?
--
--Myron A. Calhoun.
Five boxes preserve our freedoms: soap, ballot, witness, jury, and
cartridge
PhD EE (retired). "Barbershop" tenor. CDL(PTXS). W0PBV. (785)
539-4448
NRA Life Member and Certified Instructor (Home Firearm Safety,
Rifle, Pistol)