How to Test a Car Radio Antenna?


Your car’s radio uses an antenna cable to operate, and any issue with the antenna cable will cause reception problems. Considering you cannot have clear connectivity to both FM and AM signals if the car antenna or radio has a problem, you need to determine whether the problem is the radio or the antenna.

Fortunately, there are some tests you can carry out to determine whether your car antenna is the cause of the problem, but how exactly should I test a car antenna? Let’s find out.

As a general rule, to test the car radio antenna, you have to disconnect it from the radio. Then, connect one multimeter’s lead to the radio’s antenna port and the other lid to the car antenna. 

If the reading is under 5 ohms, it means there is a good connection between the radio and the antenna, and the antenna is working correctly. Otherwise, if the reading is much higher than 5 ohms, the car antenna is damaged.

Tip: When carrying out this test, you should wiggle the antenna. If the readings keep on changing when you wiggle the antenna, it means there is a connectivity problem. 

For the proper testing, you need a suitable voltmeter.

The multimeter I have been using for a while, and it works really well, is the AstroAI 6000 that can correctly measure not only all electrical parameters but also surface temperature, which is handy when you need to investigate overheating car audio elements.

In this article, I will look at different ways of identifying and fixing car antenna problems.

Remove the Antenna From the Car

If you suspect your car antenna is the cause of your radio reception problems, you can test it using an ohmmeter using three different methods.

However, you first need to remove your car antenna before testing it. Here are the steps to follow when removing a car antenna.

Identify the Type of the Antenna

Before removing your car antenna, you will need to understand what type of antenna your car uses. 

In most cases, cars use Fixed masts or Pillar mounts. The fixed masts are mounted on the car fenders while the Pillar Mount slides on the car door pillars.

Look For the Cable or Extension Cord

Check for the coaxial cord that runs from the back of the radio to the antenna. In most cars, this cable will be located behind the car’s dashboard. 

Once you find it, check whether it is one cord that runs the entire length or an extension cable. If it is one cord, detach the cord from the back of your car radio.

In the case of an extension cable, you only need to unplug the cord at the extension coupling.

Cover the Surface of the Car

Before starting to remove your car’s antenna, you need to protect the surface of your vehicle by covering it with a clean cloth to not damage the paint.

You also need to be careful when removing the antenna so that you don’t scratch your car’s paint and finish.

Lift the Rubber Grommet

Once you have placed your clean cloth in place, use a screwdriver to gently raise the rubber grommet.

Typically, the rubber grommet is the rubber around the lip of the car’s antenna. Pry this rubber part until it is loose enough to allow you to take off the antenna with ease.

Remove the Mounting Screws

Using a screwdriver, gently loosen the screws that are tightening the antenna mount.

Raise the antenna mount off the car surface and then check under the dashboard to see the place where the antenna is mounted. In most cases, this is under the front passenger side inside the car.

Disconnect the Socket That Holds the Antenna

Using a crescent wrench, undo the socket that attaches the antenna to the car.

If you are inexperienced in removing the car’s antenna or you are worried about damaging it, you will need someone to help hold the car antenna on the outside of the vehicle during this step.

This will prevent the antenna from falling and damaging the car’s paint and finish.

If there is no one to help you, you can use a clean cloth to protect the car’s paint and the antenna. Finally, remove the antenna from the vehicle by sliding the socket out.

Test the Antenna Using a Multimeter

Once the antenna is removed from the car, you can test it using three different methods using a multimeter.

Here are the steps to follow to test your car’s antenna:

Connecting the Multimeter to the Antenna Tip and Radio Antenna Port

This test measures connection between the antenna and the radio.

Connect one lead of the multimeter to the antenna and the other to the end of the cord that enters the radio.

Wiggle the antenna while checking the readings. If the reading is consistently under 5 ohms, it means the connection is good.

Connecting the Multimeter to the Antenna Base and Antenna Cable

In this method, you will be testing the connection between the antenna cable and the base of the antenna.

Connect one lead of the multimeter to the antenna cable and the other lead to the base of the antenna.

If the reading is consistently less than 5 ohms, it means the ground connection is good.

Connecting the Multimeter to the Antenna Cable and the Radio Pin

This method tests whether the connection in the antenna cable is working fine.

Place one lead of the ohmmeter on the antenna cable and the other lead on the radio pin.

If the ohmmeter readings are infinite, the antenna is correctly grounded and working fine.

If the readings are okay after carrying out the above tests and you still have issues with the signal quality, there may be a problem withing the radio itself.

Understanding the Different Types of Car Antennas

There are different car antenna types, and you need to understand them to test them effectively. Here are some of the most common antenna types found in cars.

Internal Antennas

This type of car antenna, as the name suggests, is located inside the car around the windshield, dashboard, or trunk area.

Usually, this location improves the protection of the antenna from accidental damage and bad weather. That means you may encounter minimal breakdowns if your car uses this type of antenna.

Considering that these antennas are located inside the car, their signal reception is unclear when compared to the external antennas. 

In some cars, these antennas come with a built-in amplifier that can help to improve their reception performance. However, you can improve their reception performance by using an antenna booster.  

External Antennas

The external car antennas are mounted to the car’s exterior around the trunk or hood.

In most cases, these antennas will have better reception. However, this also means they are more prone to accidental breakage or damage due to bad weather. 

Usually, these antennas are fiberglass or metal to help improve their durability. In addition, some of the external antennas are retractable, which helps protect them from damage when they’re not in use. 

Satellite Antennas

These are the latest and most advanced types of antenna used in automobiles.

They consist of a radio dock installation near the car’s dashboard or windshield. Then, connection cables run from the radio through the side or back of the vehicle to a magnet antenna attached to the car’s roof. 

Unlike previously mentioned antenna types that use free broadcast stations, satellite antennas use paid subscriptions.

However, their reception is superb, and they offer superior sound quality. 

Other Factors That Might Be Causing Signal Reception Problems

Although many people think the cause of car radio’s signal reception problems is the antenna, some other factors might be causing the problem.

Before concluding that the car’s antenna is the problem when your radio keeps on cutting out, consider looking at the following things first:

Physical Obstruction

Your car’s satellite antenna might be in good working condition but losing connection to the satellite due to physical obstruction.

Here are some situations your car’s satellite radio may cut out due to physical obstruction.

  • When driving next to tall buildings
  • When driving in places with deep valleys and mountains
  • If your vehicle is parked under a thick canopy of trees
  • If you are driving through a tunnel

If you suspect your car’s satellite radio is cutting out due to physical obstruction, you can try driving to a clear area and then see whether the radio will stop cutting out before testing the satellite antenna.

In most cases, your satellite antenna will connect better with a clear view of the southern sky.

Failing Tuner

Another reason why the radio signal may cut out even when the satellite antenna is in good working condition is the satellite radio tuner problem. 

The tuner helps in signal reception from the stations. However, when it is not operating correctly, it will not effectively pick up the signals, decode the information and convert it to the various stations.

You can try switching to different channels to verify whether the problem is caused by the tuner or the specific channel you have chosen.

Bad Wiring

Even if your antenna is working properly, bad wiring between the tuner and the antenna can make the radio cut out or cause poor sound quality. 

You can check this by physically inspecting the cables between the tuner and the stereo system with the radio playing. 

Flex the wiring and wiggle the connectors while listening to whether there are any changes in the sound quality. The wires transfer low voltage, and you don’t have to worry about the electric shock when flexing.

Keep in mind that different satellite radio stations use different audio technology, and so you should not be alarmed because of a unique sound or tone.

Interference of the FM Adaptor

You can experience signal reception issues due to the FM adapter being interfered with by a different FM radio transmitter.

In most cases, this will happen when you’re driving between different areas where the broadcasted signals can overlap each other. 

Usually, the FM adapter interference starts with the reduced sound quality.

Before testing your antenna, you can verify whether this is the problem by checking if the transmitter is working with the frequencies it has been designed for. Ensure your car stereo is then set to that frequency.

Keep in mind that your car’s radio tuner button or knob can bump to cause a compromise in sound quality, especially when driving on a rough road.

Also, a nearby FM radio station broadcast can cause an FM adaptor interference. 

Related Questions

How Can I Improve the Signal Reception Capability of My Car’s Antenna?

If your car’s antenna is correctly connected and the wiring is in good condition, but the reception capability is not impressive, you can use the following methods to improve it.

Extend the Length of an Antenna

The antenna is designed to pick up the radio wavelengths sent into the air and convert them into the sound you hear.

That means a longer antenna will pick up more signals, translating into better signal quality. Therefore, it is advisable to equip your car with an antenna that is around 32 inches long.

Improve the Location of Your Antenna

The electrical devices around your car’s engine compartment might interfere with the radio wavelengths.

That means your car antenna will perform poorly when located near the engine compartment than then when located around the trunk. 

This wavelength disruption might cause loud pops and buzzes or a soft static hissing sound.

Once you move your car antenna to a location far from the engine, remember to ground it by connecting it to the car’s metal chassis.

Install a Signal Booster

The most reliable way of improving your car’s antenna performance is by installing a signal booster or a pre-amplifier. The signal booster helps to amplify the weak signal the antenna picks up from the air. 

You can also use the diversity tuning system, which utilizes two antennas, one at the rear of the car and the other at the front, to improve the signal reception capability by switching between the antennas.

Conclusion

If your car radio keeps cutting out, the antenna might be the problem. 

With a crescent wrench and a screwdriver, you can remove the car antenna for testing. Use an ohmmeter to test the connection, and if the readings are less than 5 ohms, the antenna is in good working condition. 

Otherwise, the antenna is not working correctly, and you may need to fix it or replace it.  

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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