Stephen Sewell's review of Minimeca's steel antennas for 1/35 vehicles indicates that US military vehicle antennas are either 2.77 meters, or 79mm in 1/35th scale) or 3 meters, 86mm in length. He also indicates that "WWII US antennas are not much different," with the exception of HF command/recon machines. Not a precise answer, admittedly, but unless your estimations are radically different, probably fairly close.
Here's Sewell's review (also in AMPS
Boresight, if I recall correctly):
http://www.kitreview.com/reviews/steeantennareviewcs_1.htmI suppose the right thing to do, now, would be to order some antennas from Minimeca instead of simply stealing the measurements, and cutting our own!