you are probably talking about HF ("high frequency") and long distance communications
. This is fundamentally different from the needs for VHF
The main difference is that an SSB
signal may be bouncing off atmospheric layers, rather than "beaming" on a line of sight from one antenna
to the other. When the signal bounces off anything (atmospheric layers, skycrapers, terrain effects, etc.) the polarization of the signal changes. And that's the gotcha:
If two antennas are set up, one horizontal and the other vertical, you can lose a fast 20db of signal strength (3/4 of your power) simply from the change in polarization. That's not my opinion, that's the physics of antenna
systems. So, for two VHF
radios where it IS possible to have both antennas very close to vertical, that's a good way to do things.
But for HF systems including marine
SSB, where thesignal will be rotated as it bounces off things anyway, the polarization is not as critical and you'll often find that taking the antenna OFF vertical can improve results. This is a situation where the environment
is outside of your control, and "what works best" is literally going to need experimentation to suit your environment
and purposes, i.e. whether you are intentionally using atmospheric bounces for long range, or trying to send a signal straight up and down for NVIS (Near Vertical Incidence Signal) transmission
, which shoots an HF signal "straight" up in order to bring it back down to stations within a couple of hiundred miles of you. And that's what the military does for HF radios when they want to communication inside the local dead zone that they would otherwise have--the run the antenna parallel to the ground, not vertical at all!
Vertical? Sometimes yes, sometimes no. Best to run the antenna so it is physically robust, and then it is most likely to be there and be working--at all--when you need it. Every boat is different, every rig is different, there's no one yet who has been able to just "run the numbers" and come up with a "best" installation
compared to experimenting on it.