Posted on 26-01-2008
Filed Under (Antenna) by popwireless

How does the average consumer improve AM radio reception? What gadgets are out there to capture weaker signals? Why is AM reception so problematic in certain areas in the first place?  It just seems that in this day and age there should be a better way. What is the deal!?

Southern Maryland is practically the AM radio no-mans-land.  Populations in Calvert, St Mary’s, and Anne Arundel counties are all a considerable distance from the Washington D.C. and Baltimore radio markets.  There are few strong local radio stations and AM radio here is characterized by weak fading noisy signals.  Signals that are present more or less in the daytime vanish completely at nighttime. Stations in New York, Georgia, Ohio, other states, and even the Caribbean are stronger than local stations at night.

While time march’s on and technologies do improve the laws of physics as those laws apply to radio wave propagation never change. You can always count on science to keep radio essentially the same as it always has been. Radio waves behave in a predictable way. Even the new HD radio technologies are subject to the same physical laws. Receiving a good HD signal means we still consider the rules of radio.

Let’s look at the issues that affect the strength of the AM radio waves carrying our favorite programs to our desk-top radios.

  • The distance between the receiver and the transmitter. Your radio is the receiver of course. A radio station’s transmitter can only send a radio signal so far.
  • The radio station’s radio wave travels differently in the nighttime than it does in the nighttime. The daytime ground wave and nighttime sky-wave phenomena determine signal strength of some radio stations.
  • The quality of the receiver and the receiver’s antenna system can make the difference between a poor signal and a good signal from your favorite radio station.

OK, now that we know these things let’s expand upon them a bit and see how these items matter to the AM radio on the nightstand.

The FCC gives radio stations authorization to operate at a specific output power. Some use a high-power signal and others a low-power signal. Radio station power can range from a few hundred watts to fifty-thousand watts. Power assignment is based on frequency or how a particular frequency fits into the FCC AM band plan. Some frequencies are for local use and others for regional or wide area use. The number of stations already using the frequency and their location also effect power levels. A high-power signal provides a more useful local signal, (stronger ground wave) over greater distances in the daytime.  Why the power limitations? AM channel allocations are shared with lots of communities so many radio stations share the same frequencies. The useful signal patterns of radio stations generally are not allowed by the FCC to overlap.

The FCC coordinates radio station service areas. This means the farther away you are from a radio station the weaker the signal and the more that channel is affected by man-made or atmospheric noises that hinder reception. When you are on the outer edge of a radio station’s useful radio signal you are on the fringe hence the term fringe area.  The FCC may even dictate to a radio station that the ground wave be aimed in a specific direction with a special directional antenna array.

Mileage is not the only consideration. The usefulness of the daytime ground wave can also be affected by man-made or natural obstacles between the radio station and your receiver.  Obstacles include structures, topography (hills, valleys, mountains), and believe it or not vegetation.  It’s beginning to seem like one of those challenges we wish we didn’t have to overcome right ;) Not so. Radio has been with us over one-hundred years. Some of the realities have a technological work around.

Nighttime adds a few wrinkles to AM radio listening.  AM radio waves travel much farther at night but not along the ground. At nighttime the sky-wave or skip phenomena impacts how and what we hear on AM radio.

Remember that the FCC Rules protect interference between radio stations in overlapping coverage areas. The ground wave is not the main interference consideration at nighttime. The sky wave is the nighttime consideration. The only way to prevent one radio station’s sky-wave signal from traveling farther at night and allowing a ground-wave at another location to serve its listeners is to have radio stations reduce their nighttime output power.

A perfect nighttime example for listeners in Southern Maryland is the reception of a favorite D.C.  radio station, WTNT at 570 KHz (kilo-hertz.) As the sun goes down, WTNT is required to lower their transmitter power. This dramatically reduces the useful range of the local ground wave.  WTNT is  barely heard in Southern Maryland a few hours after sunset. Listening carefully, you can hear more than one radio station on 570 but none of them are intelligible for long. Some nights the strongest station is Radio Reloj in Havana, Cuba.

What is a listener to do? We have to use what we know about how radio waves behave to improve reception. When radio stations are extraordinarily weak I usually suggest that listeners find the syndicated programs at another radio station on the AM dial.  WTNT’s six o’clock host can be found at other dial positions above 800 KHz. Those stations are farther away, but the sky waves from each distant station are far stronger than the weak ground wave from WTNT. 

How do we improve a weak ground-wave or sky-wave signal?  That is done by improving the radio receiver’s antenna circuit.  AM sky-wave fading and poor ground wave can be mitigated to a degree by using the directional characteristics of the table-top radio. This is as simple as rotating the AM radio to take advantage of the directional ferrite-rod antenna in all AM portable radios. Simply rotating an AM radio or moving the radio to a higher location and away from obstructions can often improve signal strength.  There are long-range AM radios designed with better ferrite antennas,

Another step is to purchase a tuned signal amplifier that either connects directly to your radio or is placed near it.  Not everyone has the skills to build hobby devices like this.  My favorite places to refer consumers for reception improvement aids are the C. Crane Company’s website  and their local RadioShack store.   Mr Crane’s company offers easy-to-use products similar to devices hobbyists build to improve reception of weak radio signals.  Next your local RadioShack store is where you find knowledgeable people that also help with products they sell.

Examples of amplified antennas are the C.Crane Dual Ferrite Antenna and the RadioShack AM-FM Amplified Antenna 150-1859.  The Dual Ferrite antenna peaks or amplifies the available signal through antenna aiming and tuning of a special circuit to the desired frequency.

Another option is a long-wire antenna placed as high and in the clear as possible. This improves signal strength but not directionality. The option is not always available to everyone. You have to have enough outside space and support  to raise up at least fifty feet or more of antenna wire from the radio receiver to a high location. An end-fed long-wire antenna is also prone to picking up electrical noise. A close-by lightning strike can create high voltages at the ends of the antenna which can damage your radio.

Provide a return path to ground for the radio signal via a wire from the radio’s ground terminal to a cold water pipe or outside ground rod. This improves the efficiency of the antenna circuit for either antenna improvement option mentioned above.

The best all-round advice for consumers is to buy a better AM radio like the CCRADIO PLUS, or the RadioShack High-Performance Radio.  Select a radio that has a large ferrite-rod antenna as well as antenna and ground connections. The tuned amplifiers mentioned above are connected directly to these radios for maximum efficiency.  My personal favorite is the CCRADIO PLUS.  The design of this radio’s inner workings and hidden mechanisms alone is enough to make a big difference with AM radio reception. When I rotate the radio I get the benefit of the radio’s internal ferrite antenna.  When you live in a fringe area you deserve the best.

HD AM reception is tough. The listener must receive a very strong signal with virtually no interference before the signal is stable.  At my home the only AM radio station that has a steady AM HD signal in the daytime is WMAL 630 KHz. After three o’clock conditions change enough so that HD detection is off and on making listening tedious. Even though I can hear other stations that transmit in in HD only analog is detected because the signals are not strong enough. My sense is that listeners close to the transmitters located closer to Washington D.C. and Baltimore get great AM HD.  I have never experienced reliable AM HD sky-wave reception.

Ask questions on this topic as a comment to this article or in the AM DX forum of the Personal Wireless Bulletin Board. Click on the FORUMS link at the top of the blog page.

(2) Comments   

2 comments on “Improving AM Radio Reception at Home or Office

  1. Questions? Please post a question here or visit the PopularWireless bulletin board. Lots of wireless savvy folks read the blog and the BBS.

  2. I am trying to receive the sports am 66.0 WFAN NY.Im living in Williamsburg VA,can I do this by buying a good am antena.Some times at night I can get this station on my car radio.Im trying to listen to the Jets football on this station.Thanks,Charlie

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