Funny I was thinking of a Slot antenna for 11m CB on truck just trying to get up to speed on antenna theory of slot just getting in to radios though I would start with CB. Was wondering if one were to take a closed loop of wire around a windshield in the gap around the glass as feed point and ground to body would that be like a slot antenna or a loop antenna? And would it even be feasible at 27MHz
Many of the slot antenna on Internet and even QST are NOT slot antennas. People call them slot antennas, but they are not even remotely close to being a slot antenna. Some are nothing but bent up folded dipoles, they bear no resemblance to a slot, but somehow QST and others give these non-slots a pass. A slot antenna works, as you say, by exciting a sheet of current in a very large metal plane, such as a waveguide or an aircraft fuselage. If we do not have the large sheet or backplane, we do not have a slot. To be a slot antenna...it has to have a large sheet of current.
I suggest you get John Portune's book on slot antennas and watch his numerous YT presentations. He answers many of the questions you have.
Funny I was thinking of a Slot antenna for 11m CB on truck just trying to get up to speed on antenna theory of slot just getting in to radios though I would start with CB. Was wondering if one were to take a closed loop of wire around a windshield in the gap around the glass as feed point and ground to body would that be like a slot antenna or a loop antenna? And would it even be feasible at 27MHz
Antenna theory won’t help you much with Slot theory. They seem to contradict in most cases.
Many of the slot antenna on Internet and even QST are NOT slot antennas. People call them slot antennas, but they are not even remotely close to being a slot antenna. Some are nothing but bent up folded dipoles, they bear no resemblance to a slot, but somehow QST and others give these non-slots a pass.
A slot antenna works, as you say, by exciting a sheet of current in a very large metal plane, such as a waveguide or an aircraft fuselage. If we do not have the large sheet or backplane, we do not have a slot.
To be a slot antenna...it has to have a large sheet of current.