Most people rely on the internal antenna that’s inside your AM radio, but this internal antenna isn’t very effective. So the first thing you should try for better reception is to attach an external antenna to your receiver and then to the wall. External antennas can be purchased at any electronics store and are relatively inexpensive. Some higher-end radios, could come with two external antennas. One antenna might look like a straight piece of wire—this is the FM antenna. The FM antenna supplied might also look like a “T”; this is called a “dipole” antenna. The AM antenna looks like a black square with loops of wire wrapped around it, with a wire extending from it that attaches to your receiver, and is called a “loop” antenna.
Another option is to purchase a powered antenna or a “tunable loop”. This is a loop antenna with an amplifier built in—it can be powered by battery or can be plugged into the wall. The higher-priced units (in the range of $50 and higher) come equipped with tuning dials, so you can pick one frequency that will be more sensitive and have better reception than the rest.
For AM reception, position your radio away from televisions, dvd or cd players, computers, anything with a motor (hairdryers, blenders, etc.), and other electronics. There are circuits inside such electronics that tend to generate low-level signals. These signals can interfere with radio reception within the AM frequency range.
You might also be experiencing degradation in your AM reception in the evening. Due to atmospheric changes at night, AM signals travel farther than they do during the day. Hence we are required by the FCC to lower the power of our AM antenna every evening at sunset to prevent interference with other AM radio stations that use the same frequency throughout North America. We return to full power at sunrise the following morning. As the time of sunset and sunrise change during the year, so does the time that we adjust the power of our AM station.
Listen to WNYC's Director of Engineering Jim Stagnitto discuss the ins and outs of radio reception at this link: http://www.wnyc.org/audio/reception/