Outdoor Antenna Performance Calcs Mr. Beezley has a site with extensive FM circuit and antenna information ( http://users.tns.net/~bb ). He's modeled a number of commercial and special construction FM antennas and has provided detailed comparison of the relative performances. I've borrowed two of his performance charts and attached them for AKers. The first one is for forward gain of the antenna - how much boost does it give a signal in the direction it's pointing over the standard dipole. This is a figure of merit that is simple to understand - the higher the gain, the stronger the signal at your tuner. The horizontal axis is frequency with 88 MHz on the left increasing to 108 MHz on the right. The second is the front-to-back ratio over the same frequency band but using the worst case since antennas have back lobes that aren't always directly behind the pointed direction. This is important for the antenna's ability to reject multipath signals. Again, the higher the better. Both vertical scales are in dB. For both charts, special-built antennae outperform commercially available units. They are special built because there is no market at the price points necessary to cover the construction and shipping costs. More useful are the comparisons of the APS-13 and the Winegard HD6065P. Also on the charts is the Channel Master Probe 9 but it's no longer mentioned on their website so one can assume it is no longer offered although one might come across a NOS unit. My reading of the charts is that frontal gain of the APS-13 is just a little better than the Winegard - maybe 1 dB over the band. Where the APS-13 shines is in front-to-back rejection - there it is 10 to 18 dB better, depending on frequency. If you're in a valley or a city with lots of multipath reflections, this might make it worth the 2.5X price difference.