It’s chilly out there, and dark, but I went out to study the antenna system mounted on my auto. There is a whip antenna 28″ in length which cannot be telescoped to any other length, mounted at the front center of the roof right at the front windshield and laying back at about a 33-degree angle.
Right at the foot of the antenna, embedded in the windshield, is a fine mesh about 1.5′ wide X 2.5″ vertical, which I assume is part of an embedded antenna.
The rear window has horizontal wires embedded in the window about 1.5″ apart, which I assume are heating elements.
What do you know about embedded (surface mount) antennas?
IMPORTANT EXPLANATION – Now that I think about it ALL antennas are “surface mounted,” so let me explain what I am talking about here…… a “flat” mount antenna that lays flat on the surface and does not protrude; an antenna that in essence IS the surface, or is part of the surface.
Think PZM microphone. “Pressure Zone.”
EDITOR FOUND SOMETHING: I did a quick search and found reference to Fresnel Zone Antennas. Look at this interesting clue from the Wikipedia item:
An offset Fresnel zoneplate can be flush mounted to the wall or roof of a building, printed on a window, or made conformal to the body of a vehicle.
Car Aerials
Maybe the embedded mesh you mentioned is a ground extended into the windshield but it also could be window sun screen.
Fresnel antenna effects work at near wavelength so this is not likely to be useful for AM. The satellite link patch antennas work because they are near wavelength dimensions.
Fixed length whip antennas are usually about 30 inches long since this is near a 1/4 wavelength for FM and provides enough length to also capture an AM signal. Many are fiber cores for strength with wire wrapped helically.
Embedded antennas I have seen are simple horizontal dipole or folded dipole antennas center fed. My current SUV has an embedded diversity system where two back side windows have thin conductors embedded. Each appears as a F with four rather than two horizontal members. This is probably to spread the bandwidth for FM. The manual mentions a diversity system built into the receiver which implies two front ends are used.
Slot antennas are used in aircraft and also for undercover police applications. One such antenna operates in the UHF region and mounts in the speaker cutout in the horizontal rear deck inside the rear window of a car. This conceals the communication antenna for under cover work. Such a slot antenna appears electrically to be a vertical antenna.
Neil
what car?
what car do you have with an antenna that long?!?