Dave, if you want a more Technical answer, you may feel free to contact me off the BBS (Direct) and I will get as technical as you like. The simple version is that at its center, an antenna element is at a null point and it may (by design) be either free floating (not grounded) or grounded to the mast. Truthfully it boils down to who designed the antenna and what the designers preference was... Operationally there is little if any difference from this standpoint. Constructionally it is easier to make a grounded element yagi and of course by design they should also (unless it is a really crappy design and there are some out there) be stronger (more robust) than the insulated antennas...
Bottom line, don't worry about gain, most advertized figures lie anyway in that they give a figure devised for their own (not yours the operators) ends... If the antenna does what you want, then it is a good one, if it doesn't it is no good for you... Remember the higher the gain the smaller the radiation pattern and the harder it is to hit a target (think shotgun Vs. Rifle) The shot gun has less directional gain, and will not shoot as far, but it is easier to hit a close in target (LEO's) than is the higher gain (Rifle) antenna...
For all intents and purposes a 3-4 element yagi is all you need on 2 meters and 4-5 on 435 Mc.
DE KD1PE
Subject: [amsat-bb] Arrow vs M-Squared Antenna Question
I just received an Arrow and I already had an M-Squared 2m antenna. The M-Squared has the elements isolated from the boom by means of rubber grommets; the Arrow has the elements attached to the boom and they are not isolated. It seems to me that makes the elements, boom, mast and coax center conductor all grounded. Right?
Doesn't that make the Arrow less effective in radiating and in reception?
Dave // DM78qd // KA0SWT Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb