Has anyone tried shaving their antenna and using the rear defrost grid, like many newer cars do? I'm thinking of trying it, and just wondering if anyone else has. A small capacitor should block the DC voltage from it, while allowing RF through. I'll have to dig around and find out what size capacitor would be needed, but I think it would work better than an under-dash antenna.

 

you can buy them for the front window.

 

Yeah, i've seen the thin wire antennas that go in the front windshield, but it seems to me that there's already a huge grid on the back window, which should work well as an antenna. Plus it doesn't require any other parts than a capacitor, and some coax cable.

 

seems like an interesting idea *subscribing*

 

Seems like it might be viable. Did you think about separating out just part of the grid? I'm no expert, but I'd be afraid that the large grid may pick up a lot of other electronic noise that you don't want.

My '77 Impala had the antenna embedded in the front windshield, reception was great. I'm not sure why GM didn't stick with that years ago.

 

I think you mean diode.

 

No, a capacitor, to block DC voltage from the defroster (when it's on). A diode would block both DC and AC voltage, including RF. I don't think electrical noise should be too bad, since it's away from the engine bay. I also though about cutting part of the grid and using it for antenna only, but then I have to solder another wire to the grid. I would like to use the factory wire to the grid if possible, and as splice in as close to the grid as possible.

Edit: Quick diagram on how I plan to wire it, I think this would work:

 

sounds good. I say you go to Radioshack and try it! let us know if it works

 

Looked at the diagram and looks like if you cut both sides of the grid (power in and ground) then solder the center conductor of coax to either side and the shield to the ground. You should be in business. Not the ground side of the grid but ground as in the body of the car.
As for capacitors you would realy do better with a diode as a cap stores power till it is needed and could discharge to your radio and a diode can allow power to flow 1 way not the other and will even blow if power flows the wrong direction therefore protecting the radio from power flowing back down the coax and in thru the ant hookup.Like the diodes in CB radios that tend to blow when the radio is installed backwards.
I maybe wrong but I've been workin or CB& hams for about 20 yrs now.Have built a number of antennas and made many a repair due to improper radio and antenna instalations.I've got a nice collection of radios from people crossing wires and blowing what amounts to basicaly a 10 cent reverse polarity diode poping on the board.
If you want to get real fancy I'm sure it's even possiable to "tune" the grid to close to a correct bandwidth and potentialy improve channel rejection/reception.

 

You'll need two coils. Put one in series with the positive side of the grid and one in series with the negative side. Connect the coax across the coil on the negative side. No need for caps or diodes as there won't be much DC to speak of. If you can't get coils made for the purpose you can fab them from a heavy gage magnet wire. I'm not sure of the optimal number of turns, but I guess 10-20 turns with up to 1/2" diameter should do the trick.