You've been there. Listening to the radio in your car, taking in interesting
news, excited to hear what the radio host might say to the next caller,
or feeling the tension of a close baseball game. And then you get home,
or arrive at work. You know it will take just a couple minutes to get
inside and turn on the radio, so you wait for the station break or
the end of an inning to make your move. Finally, you're inside and
out of breath from running to your radio. You turn it on, tune in the
station, and . . . huh? What happened? The reception is terrible! The
signal was clean and clear in the car, but it fades in and out inside.
Or it's full of static. Or it's just plain gone. You wonder if something
is wrong with your radio, if the antenna is broken, or if the tuner
isn't precise enough. Maybe you grab your keys and decide to go back
out to your car, catch the rest of the program or the game there. Why
does this happen?
Though it may seem sometimes like your car radio is better than any other
radio you own, it's not really such an exceptional receiver. The small
whip antenna on your car actually combines with the car's metal body
to produce the affects of a much larger antenna. Your car radio is
also specifically tuned for the coaxial feedline and whip antenna to
give you the best reception for a small antenna. You can test the sensitivity
of your car's whip antenna by tuning your radio to a weak AM station
and touching the whip antenna with your hand. You'll hear a lot of
static and noise coming from all the atmospheric electrical noises
bombarding the radio's sensitive amplifiers.
Two of the most common problems related to poor AM reception are radio
noise interference, and weak AM reception. If you are dealing with
a radio noise and interference problem, you'll probably notice that
your radio gets noise on AM but not on FM. That's because AM transmits
on a very low frequency compared to FM, and AM is more susceptible
to the radio-made noise from almost every electronic device within
the vicinity. If you suspect that your home or office radio's reception
problem is caused by interference coming from another electronic source,
please visit our Radio
Noise and Possible Solutions page for a very informative
radio interference troubleshooting guide.
Car stereos are also succeptible to radio interference. The interference
you hear can be caused by your car's own electrical components. If
you hear a high-pitched whining noise that changes when you step on
the gas, the noise is most likely coming from the alternator, distributor
or sparkplug wires. Keep in mind that audio interference problems can
also be caused by your vehicle's fuel pump. The final and least common
possible source for radio interference occurs when noise generated
by the on-board computer is transmitted to the hood and then retransmitted
to the antenna.
NOTE: In many cars with electrical noise problems just putting the key into
the ignition and turning it to the "on" position, and wiggling the
key without starting the car may cause AM radio noise.
The other common problem related to poor reception is basically a weak
signal. A station having a low powered transmitter can cause this problem.
On the other hand, you may be tuned into a strong 50,000 watt powerhouse,
but you are so far from the transmitter that by the time the signal
reaches your receiver, the signal has lost its stamina. As a final
point, if you are listening to a strong local station, but you find
that you are still experiencing poor reception, the most likely culprit
is simply a poor receiver or antenna.
If any of these AM radio reception problems sound familiar, or if you're
not happy with the performance of your car radio, keep
an eye out for our next What's in the News article, where we've
put together some ways to diagnose and fix common radio noise and weak
AM reception problems discussed in this article. Be sure to check out
the next article where we'll give you the answers to the The Car Radio
As always, please contact us with any comments or
article suggestions you might have.