antenna differences
The difference is the length of the actual antenna element inside of the plastic housing. Antennas are designed for specific frequencies and are physically limited to those frequencies. Antenna tuners and matching devices rob power from your transmission and should not be considered. Buy the VHF antenna, put it as high as you can. Just as important, use high quality cable and connectors. We seal connectors with one layer of butyl rubber tape, followed by several layers of electrical tape. Exposed cable shielding will degrade over time. One thing to think about - antenna gain is a redirection of radiated power. Picture an antenna radiating energy in all directions, like a sphere. Then, squash the sphere and it pushes the energy outward horizontally. This is what a higher gain (omnidirectional) antenna does. The "gain" is actually the energy radiating that was radiating above the antenna redirected out horizontally. You don't actually increase your signal, you radiate more of it in the same place. The higher gain antennas have a flat radiation pattern. This could be a problem on top of a mast on a boat heeled over at 15 or 20 degrees. On one side the majority of your signal is radiating into the sky and on the other it is directed at the water. A lower gain antenna will out perform the higher gain in these conditions. Sorry to carry on for so long.