Three parallel planar antenna designs for large area plasma source are investigated using double probe and B-dot probe. Butterfly antenna has highest density of $0.8-2×10^{11}cm^{-3}$ with highest density at center and has 1.5-2eV electron temperature which is lower than spiral antenna of 3eV. It is shown that power efficiency becomes low when there is closely spaced parallel antenna elements with oppositely directed currents or when elements with positive coupling.
