A 1.5dBi antenna is less effective at concentrating its power in any particular direction, but, by the same token, is not too badly affected by being used at an angle. This is useful for portable radios.
The “feeder” cable connecting the antenna to the radio is an important part of the whole system. The cable used for domestic televisions and radios may look the same as is used for marine VHF antennas, but its electrical properties are quite different, and will severely detract from the antenna’s performance.
Batteries
Marine VHF radios are almost invariably powered by batteries, whether they are internal, as in most portables, or are the boat’s domestic batteries.
All batteries work by using chemical reactions to produce a flow of electrically charged particles, called electrons, in the circuit that links the battery’s positive and negative terminals. The fundamental difference between rechargeable and non-rechargeable batteries is that in rechargeables, the chemical reactions can be reversed by pushing the electrons back through the battery in the opposite direction.
Alkaline batteries are not normally rechargeable, but they are readily available, and store a lot of power for their size and weight. Although they are not an economical option for regular, long-term use, they are a very useful reserve power supply for some portables that are designed to accept them.
Lithium batteries are expensive, and not rechargeable, but they produce a lot of power for their size and weight, and have a very long shelf life. This makes them ideal for emergency equipment such as EPIRBs or for portable radios which are reserved for emergency use. Like alkaline batteries, they produce 1.5 volts per cell when new.
Lead-acid batteries are very heavy and bulky, but they are rechargeable, and are produced in large sizes that make them an economical way of storing a lot of power. Not surprisingly, they are the standard type of battery for engine starting and domestic services on boats.
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