Is there a theoretical reason why the gain resulting from stacking two HF yagis over real ground is limited to 3 dB? I have a model of two C-3Es that shows 3.5 dB increase over a single C-3E in the top position. I'm trying to figure out if this is a modeling anomaly of some sort... 73, Pete N4ZR Check out the World HF Contest Station Database at www.pvrc.org