Absolutely, you would need a counterpoise. An eight foot ground wire
would only function as a tuned RF conductor at 10m where it is a quarter
wave long, but it would be high impedance at the shack most likely.
At any other band, the length of 8 feet is not enough of an RF resonant
conductor nor of such a diameter, typically, to have low RF impedance.
Ground rods are a DC and 60 Hz safety convention. Most soil is very
poor at best at RF frequencies. Your counterpoise actually acts as an
insulated antenna element, and does much more good for you, and balances
the loaded antenna element, which is itself short for the purpose of
being a radiator at a ham band frequency.
An old ham myth is that a ground rod is sufficient as an RF ground. It
should be used for a safety ground, but not relied upon for an RF
ground. It may work if your local soil conditions are very conductive,
but the whole interface of it to the soil and the soil itself is an
inefficient RF element.
You don't have enough surface area on the typical rod to have low enough
impedance at RF.
GL and 73,
TenTec mailing list