AM radio signal strength

[ironhat]

I live in a low area and reception of all sorts is fair to poor. For example, before cable TV we had an antenna on a 40' mast, a signal booster and a rotor to align the antenna. Even with that we could get one station fairly well and two others very poorly. Anyway, it seems that AM signal is generally not very good at longer distances and in the winter, as soon as it is dusk the signal is unlistenable (my own word creation!). So, even on a good day in the middle of summer is there anyway to boost signal strength? I'm guessing not.

[Uncle Cracker]

There's no way to truly boost any signal except at the source. Aftermarket "boosters" are nothing more than amplifiers, which take the incoming signal off the air and increase it, including all the noise and background. Then some units have filter circuitry that attempts to remove some of the extraneous portions of the signal, but always lose some of the "good stuff" at the same time. FM is better suited for stereo and data broadcasts, and frequencies can be packed together tighter on the airwaves, without bleeding over onto adjacent frequencies. AM signals don't carry well because they are basically line-of-sight, and because the better functionality and popularity of FM has led the better funded broadcasters (with the biggest honkin' transmitters) away from AM. There's not much you're gonna be able to do to help your situation except to try to catch your programming when reception is best.

[ironhat]

Thanks, UC. Just as I suspected.

[gsmittle]

I live in a low area and reception of all sorts is fair to poor. For example, before cable TV we had an antenna on a 40' mast, a signal booster and a rotor to align the antenna. Even with that we could get one station fairly well and two others very poorly. Anyway, it seems that AM signal is generally not very good at longer distances and in the winter, as soon as it is dusk the signal is unlistenable (my own word creation!). So, even on a good day in the middle of summer is there anyway to boost signal strength? I'm guessing not.

It could be the station's license, too. Back in the day I worked at an AM station that had to sign off an hour after sunset every day. Also, there's more ionospheric interference after dark.

At least that was the way it was explained to me. Guess I should have studied for the Class 1 license after all...

g.

[Sid]

Check out the radios and antennas at www.ccrane.com

I have the CCRadio Plus, which does better than most radios when atmospherics or signals are poor. The descriptions of some of their special antennas sound good, but I don't have any experience with them. You could call and talk with their techs, and they are good about accepting returns.

Sid

[gerti]

The type and size of the antenna makes a huge difference. Way back the in the day when I was an AM teletype operator in the German army we used, depending on circumstances, either a 16 foot flexible rod (sometimes tied back for better results), a 100 foot wire coming at a 45 degree angle from a 100 foot pole, or 2 100 foot wires suspended between 3 100 foot poles. It was not uncommon that we had to aim the antenna in the opposite direction from the source, as we actually got better reception on the signal that went around the globe. That was typically the case when the source was between 40 and 60 miles away, which is just to far for the ground wave (line of sight), but to close for the first wave reflected by the atmosphere.

[LinuxRandal]

Depending on the type of station you listen to, and its budget, you might consider seeing if they stream their broadcast on the web, and listen that way. They do (at least some), have different links for broadband or dial up connections.

[Slik Geek]

Check out the radios and antennas at www.ccrane.com

Thanks for the link, Sid. You provided me with a Christmas gift source, one where I was having a hard time finding what I wanted.

[Daryl]

The FCC requires most am stations cut their signal strength at night because of ionicsphere skip, where a signal will skip clear around the world making it impossible to pick one station. In my opinion your best bet is to erect a long wire antenna at right angle to the station you are trying to receive and use an antenna tuner to get the optimum signal. You can get a wealth of information on radios, antennas, and signal propogation from the Amateur Radio Relay League.

[JR]

AM singals actually travel farther after dusk. So the FCC regulates transmission power, requiring some stations to reduce power at sunset. There are seven (IIRC) AM stations in the USA which have the right to transmit 50,000 watts "clear" 24 hours a day.

KDKA in Pittsburgh is one of those stations. I'll bet you receive their signal at night with no problem. Others inlcude (going from memory) WLS (Chicgo), KOMA (Oklahoma City), KNX (Los Angeles), WSB (Atlanta) - memory fading now, um I dunno something in NYC.

Ok, I looked it up and my 30-year old knowlege is wrong and not up to date. Look at Widipedia for the facts. http://en.wikipedia.org/wiki/Clear_channel

JR

[gsmittle]

AM singals actually travel farther after dusk. So the FCC regulates transmission power, requiring some stations to reduce power at sunset. There are seven (IIRC) AM stations in the USA which have the right to transmit 50,000 watts "clear" 24 hours a day.

KDKA in Pittsburgh is one of those stations. I'll bet you receive their signal at night with no problem. Others inlcude (going from memory) WLS (Chicgo), KOMA (Oklahoma City), KNX (Los Angeles), WSB (Atlanta) - memory fading now, um I dunno something in NYC.

Ok, I looked it up and my 30-year old knowlege is wrong and not up to date. Look at Widipedia for the facts. http://en.wikipedia.org/wiki/Clear_channel

JR

Also KMOX out of St. Louis.

g.

[LCHIEN]

JR is correct that AM signals do propogate better at night which is why some stations are restricted as to night transmission and other stations have to reduce power. Possibly your station becomes unlistenable at night due to othere stations signals walking over its signal because it has reduced power or shut down for the night.

UC is correct that the only way to increase power is at the source. However, You can increase the relative power through selective receiver methods. That is, increase the signal relative to background noise/interfering signals.

Off the top of my head some of the ways to do this are
1) have a directional (more sensitive at certain angles rejecting signals from other angles), steerable antenna - unfortunately for AM the wavelengths are quite long and the directional antennas huge and unweildy. However, if you only want to receive one specific station, a long wire antenna matched to 1/2 wavelength, strung out in the direction of the station transmitter might help... we're talking 100 yards or more... (I really didn't do very well in my fields and waves class...)
2) have more selectable receivers. You need to buy a special, high quality radio receiver, some shortwave receivers have these features, that allow you to tune by bandwidth as well as frequency, and also slightly off frequency. These type of receivers have improved rejection of unwanted signals and allow you to cut into the signal you are seeking to also reduce interfering signals. These are radios designed to receive very marginal signals and not your off-the-shelf low cost consumer-grade receiver (whose AM section was an afterthought to the FM-multiplex radio and cassette/CD player).

I might suggest calling your favorite AM radio station (on the telephone), and ask to talk to the station engineer. Describe to him where you live, what the specific problems are and ask him what you can do to improve reception. he would be most familiar with his station characteristics (night vs day transmissions), the effects of local terrain, and the coverage in the local area and techniques to improve reception. I think he would be more than glad to help as it is his job to maximize the number of people in the area who can receive his signal.