In article ,
"gatt" wrote:

"EDR" wrote in message news:100620041637580530%

Was there an aircraft parked somewhere in the runway environment
(beyond the hold-short line) between you and the the ILS antennas?
The glideslope signal is reflected off the flat ground between the
antenna and the runway threshhold. Hold-short lines on the taxiways are
placed far enough back from the runway that an aircraft in the runup
area will not interfer with the glideslope signal.

Shouldn't have been. It was right after tower closed for the evening and
the only other aircraft reporting was a National Guard helicopter taxiing
for closed traffic (IFR minimums...low clouds/fog)

Didn't have to be an aircraft. Could have been anything big and metal.
Like a truck. Or a tractor mowing the grass (but I suspect they don't
mow the grass late at night). But why are you so sure it wasn't the
chopper?

You might want to file a NASA report if you can't find anybody else
interested in listening.