An antenna is the interface between radio waves propagating through space and electric currents moving in metal conductors being used with a transmitter or receiver. In transmission, a radio transmitter supplies an electric current to the terminals of antenna, and the antenna radiates the energy from the current as electromagnetic waves (radio waves). In reception, an antenna intercepts some of the power of a radio wave just to produce an electric current at its terminals that is applied to a receiver to be amplified. Antennas are important components of all radio equipment.
An antenna is an array of conductors (elements) which are electrically connected to the receiver or transmitter. Antennas can be made to transmit and receive radio waves in all horizontal directions equally (omnidirectional antennas), or preferentially in a particular direction (directional or high gain antennas). An antenna might include parasitic elements, parabolic reflectors or horns, which serve to direct the radio waves into a beam or other desired radiation pattern.
The first antennas were built in the year 1888 by German physicist Heinrich Hertz in his pioneering experiments to prove the existence of electromagnetic waves predicted by the theory of James Clerk Maxwell. Hertz put the dipole antennas at the focal point of parabolic reflectors for both transmitting and receiving.
4 Ways to Fix the Car Radio Antenna
Electric-powered, self-extending antenna masts used to be like a tell-tale sign of a fancy, feature-laden car. As is the case with many electromechanical parts, however, power antennas mostly end up requiring repair. Today, power antenna masts have changed to fixed antennas or wires embedded in windshields, but there are still plenty of cars out there with these telescoping menaces. Broken antennas get stuck all the way up, all the way down, or even often somewhere in between. The shabby appearance or stunted radio reception on an otherwise perfectly good car means that replacing or repairing an antenna is a worthwhile fix.
Below we’re going to walk through the general steps of removing the whole assembly, taking it apart, then cleaning and replacing the problem parts.
Step 1: Extract the Problem Part
First, you’ll have to get to the mechanism. If the antenna is rear-fender-mounted, remove the trunk trim panels in order to gain access. Front-fender units might be inside the engine bay or behind the inner fender. You’ll likely require a few screwdrivers and wrenches. The mechanism is mostly easy to remove—loosen any bolts and disconnect the ground strap, antenna signal wire, and motor-control wires. Be vigilant with the connectors because they will be reused. Remove the assembly through pulling the antenna mast down through the fender.
Step 2: Dissect and Diagnose
Uncover the device’s guts through extracting the cover screws. Carefully remove the housing and gear cover, as the nylon cord in it might spring out and fling smaller parts. Inside, you’ll notice how the motor, gears, and nylon rope work together. If the teeth on the rope or gears are stripped, you’ll require to remove all the broken pieces. There will undoubtedly be old, dirty grease that may or may not be the problem but needs be cleaned out. Check everything else for signs of damage; if a major part such as the housing or motor is broken, replace the whole assembly.
Step 3: Fix the Bits
If the telescoping mast is the problem, just remove it by taking off the bushing at the top of the guide tube; it keeps the mast in place. Using a firm grip, pull the mast out along with the nylon rope; pliers may be needed. Clean everything, which includes the gears, with a mild cleaner like dish detergent. Lubricate the clean gears and housing with the help of white lithium grease; it works well even at low temperatures.
Step 4: Reinstall the Unit
If new gears are called for, assemble them like before; most of the time they just drop into place. Compress the mast completely and run the nylon rope down across the tube, then seat the base into the housing. You might need to gently tap it home with a hammer. Fully extend the antenna, then mesh the end of the nylon cord back into the gear drive and then reassemble the cover and housing. With the mechanism still loose, plug in the electrical connections and then turn the radio on and off. This should make the gears to pull on the nylon rope and retract the mast. If the mast doesn’t go down, the gears of the nylon rope might not be properly aligned, so you’ll have to try again. Reinstall the assembly and bolt the mast by bushing it back in place. Now enjoy it.