Does a Car Radio Antenna Need to Be Grounded


Poor grounding of any component of car stereo hinders the performance of your car’s sound system. Many car stereo repair experts look for the grounding of the system before repairing anything else.

But, how that works in the case of antennas, and are they need to be grounded? Let’s find out.

Like other components, a car radio antenna needs to be appropriately grounded. Otherwise, you will hear more static noise due to high SWR ( standing wave ratio) levels than music. In addition, bad grounding decreases the performance of car radio.

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Tip – We can check if grounding is done correctly by using a multimeter. Just check the resistance between the antenna’s mount (or coax) and the battery’s ground.

If the reading is zero or the multimeter shows little resistance, then the circuit is complete, and your antenna is grounded. 

The multimeter I have been using for a long time, and I am happy with its work quality, is the Crenova MS8233D. It is available on Amazon, so if you do not have one, click the above link and check its latest price.

We do the grounding of the car antennas because it allows passage of excess voltage to the ground. If grounding is not done correctly, this voltage bounces back to the antenna and radio, causing poor performance. Grounding is also helpful in protecting the electronic components of cars.

In the article below, I will explain the grounding principles and drive you in detail to make proper grounding for your car antenna. 

How Are Car Antennas Grounded?

No matter what kind of electronic device you install in your car, you need proper grounding.

The antennas that need a direct connection with the ground to function correctly are the monopole antennas. You can find their grounding connection bolted in the chassis of a car. 

When you open the place near the antenna (trunk or hood), you will find two wires running from it. Trace the single black wire, which is not going to the radio but the car chassis. 

Sometimes, the battery’s negative terminal is used as a grounding terminal, but it’s not a good practice.

The reason is that the negative terminal’s voltage(-12.6 V) is below ground level (0 volts) and is different from radiofrequency ground level. Therefore, it is better to use a chassis or bare metal as ground. 

Why Do Antennas Have Two Wires?

Most of the car antennas have two wires – one goes to the radio, and the other is for grounding. 

The wire that goes from antenna to radio (called antenna pin wire)is usually a shielded coaxial cable to prevent the loss of signal and interference.

To complete the circuit, we need a grounding wire which is usually black and whose function is to ground excess voltage.  

car radio antenna needs to be grounded

You can see that some car radios come with three wires. The black one is for grounding only, and the other two are red and blue.

The red wire takes a constant input of 12 volts which turns on the antenna, and when the blue wire gets 12 V, the antenna gets extended. 

How Do You Ground a Car Radio Antenna?

As I mentioned above, the perfect place to ground the car radio antenna is the car’s chassis or frame, but it is also important to have a clear path of the wire between the antenna and the grounding point. 

To properly ground the car antenna, follow the few steps below:

  • The first step is to locate the grounding wire, and to do this, open the hood of your car near the antenna, and you will find two or three wires. Usually, the black one is the ground wire, and you can check it with a multimeter. 
  • Now take this wire and find a nearby bolt on the car chassis. Many professional car stereo installers ground the car antenna to the vehicle’s factory grounding points.
  • Remove the bolt with the appropriate tool, and if rusted, clean it with sandpaper or a wire brush. Also, remove the insulation of the ground wire. 
  • You can also apply dielectric grease on the bolt and the copper of the ground wire. The dielectric grease will form a layer that prevents the building up of rust and keeps moisture away.
  • Wrap the copper part of the grounding wire on the bolt and then tie it back into the frame. You can also verify the connection of the ground with a multimeter. 

You can also make your grounding point by making a hole in the vehicle body panel and using a nut bolt. The downside of doing this is that this point can become corroded over time. 

Can You Ground the Antenna Anywhere on a Car?

A grounding point acts as a conductor between positive and negative terminals. Due to the grounding point, the headlights, door locks, car radio, and other electrical components work. 

You cannot ground the antenna anywhere on a car because if you select a bad grounding point, the excess voltage will not be conducted to earth, and your car radio may not work correctly. 

A good grounding point for a car antenna can be only a bare metal surface (without paint) because it allows electric current to pass through it to the ground and ultimately closes the circuit. 

Actually, there is a difference between good and bad grounding points. 

A good grounding point can conduct an unlimited amount of voltage and minimize the building up of static currents in the circuit.

On the other hand, bad grounding points like painted or rusted nuts and bolts act as insulators and do not allow proper earthing. 

The best grounding point in a car is the existing factory grounding point, but its location is different in different vehicles.

For various models, the grounding point is located in the chassis of a car, near the glove box, or behind the removable panel on the driver or passenger seat, and it looks like metal studs. 

Which Antennas Do Not Use the Ground?

The dipole antennas do not require a grounding connection because they already have two conductors to generate or receive signals, unlike monopole antennas that use a metallic conductor and ground.

The dipole antennas use one conductor as a reflector; therefore, there is no need for grounding. Dipole antennas are also considered balanced antennas. 

A dipole antenna is a type of transducer which converts electrical signal to EM signal at the transmitting side and converts EM signals to electrical at the receiving side. 

A dipole antenna consists of two conductors such as metal rods or wires that act as dipoles and are separated by an insulator with a source (radio frequency) connected at the center.

The length of the conductor is approximately half of the maximum wavelength (λ/2). The most common example of a dipole antenna is the rabbit ear television antenna.

The most commonly used antenna is the half-wave dipole antenna because the current distribution is almost sinusoidal along the length of the dipole. 

The current and voltage flowing through two conductors produce EM waves which are radiated outwards at the opening. 

Conclusion 

Most cars use monopole antennas, so grounding is essential, and the grounding point should be of good quality.

Grounding not only enhances the performance of your system but also protects it from sudden voltage surges. In addition, the proper grounding of the antenna improves the reception of the radio. 

Martin

Welcome to ImproveCarAudio! I am Martin, and I love to write about everything related to car sound systems. I strive to provide the most accurate and helpful information about car audio through extensive research, as well as my experience with car audio installations.

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