Quote:
Originally Posted by Sailor Steve
I believe you. You have to know something exists before you can look it up.  |
Yuppers, I'm with Steve & the others who knew (and used these) long before there was an Internet with which to look them up.
Those of us who've operated and/or repaired HF radios for fun and/or profit have used loop antennas for receiving for years because they *are* directional. I use wire antennas exclusively for transmitting, cuz they're inexpensive, but I've got homebrewed tunable vertical loops because they can be turned to null out interfering stations if they're on a different bearing from my station than the one I'm trying to talk with. Even with the reduced efficiency of a loop over a longwire or dipole (like the ones rigged from bow to sail and aft on the boats), the fact that they're so directional is frequently enough of a benefit that they're easier to hear with than the transmitting antenna. On a U-boat, since the wire antenna is so close to the surface of the water, on just the highest frequencies the wire antenna will somewhat favor signals off to the sides over those going forward or aft. On the lower frequencies, the wire antenna will be virtually omnidirectional.
Radio direction finding antennas are a nice passive version of radio for surface, kinda like the hydrophone without the sonar going active when submerged. And it is a nice way to spot enemy vessels beyond the visual horizon, especially when they're not using radar for us to detect.
It's also a nice way to be able to tell in what direction allies are if you copy their radio traffic, faster than doing a navigation fix after a best guess by dead reckoning after a long period submerged.
At my station, I've got switches to select whether I receive with the loops or the dipoles, on the fly. Propagation isn't always symmetrical, so it pays to be able to compare signals.
And if your wire antenna has gotten fouled or torn away by gunfire or depth charges, you can transmit on it, albeit with more time spent tuning to resonance than the longer wires.
In a pinch, early receivers can even be set to transmit a weak signal in case the "real" transmitters have been hosed by weapons, Murphy's Law, or by Bernard drinking battery acid in the comms rooms and then doing a spit-take on the radio panel....
Sorry for the lengthy post, but despite my newness to subs, there are a couple of related subjects I've got some experience with. This is one I share with Steve.
Zygoma
May your number of surface activities exceed your dives by precisely one when you retire.