Anyone use an antenna like this? (Rooftop AM-FM-XM)
12-12-2007, 03:54 PM
#18
928 OB-Wan
Rennlist Member
Rennlist Member
these are specially made to not have interference caused by metal or electrical components in the vehicle
12-12-2007, 04:22 PM
#19
Chronic Tool Dropper
Lifetime Rennlist
Member
Lifetime Rennlist
Member
Umhhh--
Notwithstanding the cliam that these are "specially made" to not have interference with metal or electrical components in the vehicle:
The antenna shown is a simple dipole antenna that you can emulate easily. Go find an antenna extension wire at a parts store, about 48" or longer. Strip back about 24" of the insulation from the female end, after cutting the connector off. You want to get the inner conductor and its insulation threaded out of the shield right at the place where the outer insulation ended. Pull the center conductor in one direction, and the remaining shield braid in the other direction so they form a T. Stretch the braid out, or cut it off and use a piece of regular insulated wire 24" long, soldered to the braid at the split point. Now put the two wires across the top of the dash, plug the male end of the wire into the antenna connection on your radio, and give it a try. If it's good enough for your area, you can buy the one shown or just keep your little wire dipole antenna as a permanant solution.
-- Commercial FM broadcasting is vertically polarized, so an antenna that is mounted horizontally will give up some effectiveness.
-- AM broadcasting requires a much longer antenna. The flat short dipole is a compromise. Consider the typical 32" wire whip used on cars. Then look at the short 14" whip used on the later S4+ cars on the roof, used with an amplifier.
-- Mounting any antenna right next to a metal surface reduces its ability to capture radio signals. While any of these may work fine laying on top of the plastic/foam dash, they will not be as good as a mast in free air.
-- These are not intended for satelite or GPS receivers. However, you might want to refer to Keith W's install where he put those two antennas inside the third brakelight housing in his GTS. Antennas are completely out of sight but have clear views of the satelites needed for reception and navigation.
HTH!
Notwithstanding the cliam that these are "specially made" to not have interference with metal or electrical components in the vehicle:
The antenna shown is a simple dipole antenna that you can emulate easily. Go find an antenna extension wire at a parts store, about 48" or longer. Strip back about 24" of the insulation from the female end, after cutting the connector off. You want to get the inner conductor and its insulation threaded out of the shield right at the place where the outer insulation ended. Pull the center conductor in one direction, and the remaining shield braid in the other direction so they form a T. Stretch the braid out, or cut it off and use a piece of regular insulated wire 24" long, soldered to the braid at the split point. Now put the two wires across the top of the dash, plug the male end of the wire into the antenna connection on your radio, and give it a try. If it's good enough for your area, you can buy the one shown or just keep your little wire dipole antenna as a permanant solution.
-- Commercial FM broadcasting is vertically polarized, so an antenna that is mounted horizontally will give up some effectiveness.
-- AM broadcasting requires a much longer antenna. The flat short dipole is a compromise. Consider the typical 32" wire whip used on cars. Then look at the short 14" whip used on the later S4+ cars on the roof, used with an amplifier.
-- Mounting any antenna right next to a metal surface reduces its ability to capture radio signals. While any of these may work fine laying on top of the plastic/foam dash, they will not be as good as a mast in free air.
-- These are not intended for satelite or GPS receivers. However, you might want to refer to Keith W's install where he put those two antennas inside the third brakelight housing in his GTS. Antennas are completely out of sight but have clear views of the satelites needed for reception and navigation.
HTH!
