A halfwave antenna is an electrical half-wavelength long at its operating frequency. For marine VHF frequencies, that’s approximately 935mm / 37in. A transformer is needed to match the antenna to the coaxial cable, which makes the overall length about 1.1 metres/ 43 5/16in.
A colinear antenna has two or more radiating elements. They work together to create a long, narrow “lobe” of transmission, which allows it to enable contact with more distant stations. The increase in performance is called "gain".
There’s no difference in electrical performance between the UltraGlass and stainless steel antennas in the SeaMaster Pro and SeaMaster ranges. Both are halfwave antennas. The stainless steel whip antennas are light, low windage antennas for installation on a mast, usually the highest point on the boat. The UltraGlass antennas have the radiating element at the top of the radome, which gets the antenna as high as possible for deck, side or rail installations. Our larger, white UltraGlass antennas make a boat look “better dressed”.
In the LongReach Pro and LongReach ranges, UltraGlass antennas may be either halfwave or colinear antennas. Colinear antennas have higher gain and are suitable for larger more stable vessels which may need communications at maximum range.
Smaller boats should fit longer antennas, because higher antennas can “see” further than shorter antennas. Bigger boats, where the antenna mount may be several metres above the waterline, can achieve the same horizon range with shorter antennas. We make both sizes because many small boat owners find the 2.5 metre antenna too long, and 1.8 metre antenna seems to be the right size for most trailer boats.
Some of the 2.5 metre antennas in the LongReach range are colinear antennas, which have more than one radiating element, requiring a longer radome. LongReach colinear antennas are recommended for larger more stable vessels which may need maximum range communications.
VHF, AM/FM and Cellular antennas are all available in 1.8 metre and 2.5 metre sizes, so VHF antennas can be “twinned” with either an AM/FM or a Cellular antenna.
This is due to the branding and positioning of each product range. The stainless steel ferrules on the LongReach antennas are stronger and the polished finish helps dress the boat, especially if the antenna is installed with one of Pacific Aerials’ stainless steel mounts.