Yacht Cellular WiFi Antennas – dB gain and dB Myth/Marketing
Yacht Cellular WiFi Antennas – dB gain and dB Myth/MarketingWhen a yacht Internet Connection system of the WiFi or Cellular type is installed on a yacht, usually there is an amplifier a coaxial cable and a marine type omni-directional antenna. That will be one of those 2 to 4 foot (approx.) white vertical antennas. They have to be made specifically for the application, which means the purpose and frequency band or band(s) that it will be used for. Often these antennas have a specification as to Gain. Antennas don’t really amplify a signal, they cannot. They are not an active electronic component, meaning there is no powered electronic components in them that could amplify a signal. They are basically just a radiator of radio frequency (r.f.) energy. Now, grant it they are a very special kind of radiator. The intention being to put as much of the energy in the best possible area, and to try and concentrate also on receiving from the best possible area. This area has to be 360 degrees around because a yacht can and does move. And you never know which way you are going to dock or anchor the vessel. So the antenna has to be able to cover “all around.”
Vertical Omni-Directional antennas have “Gain” by pulling in the vertical rf beam width. They gain by concentrating more energy where it is needed rather than wasting it more up and down where it is not needed. The gain works in both directions, transmit and receive. Such antennas are usually compared to a non-gain antenna (either theoretical “isotropic” or a common “dipole” antennas). In this case comparison is “dBi” so comparison is to Isotropic. There’s a funny PUN on the dB-whatever used in marketing. The call it “dbM” for db-Marketing. 8 to 9 dB gain in marine wifi or cellular is pretty much standard stuff. They’ve got to be careful not to pull the vertical beam width pattern in Too Much or you could miss the access point (or cell tower as the case may be) altogether either by under or over shooting it. Antenna should be placed as high as possible on a yacht… hopefully with nothing close by on the same height level. Sometimes there are tradeoffs to get it up there somewhere. But generally you don’t want anything like a large radar or satellite antenna to be in its path.
[That’s all for now. If you have any questions on this please contact me.]
Alan Spicer Telecom / Alan Spicer Marine Telecom
+1 954 683 3426
communications (at) marinetelecom.net