Once, deep in Baja, I was listening to a lot of AM radio from the states, and found if I touched my stock antenna, a bunch of background static disappeared.
I took a wire with a toothed clip on one end attached it to the antenna, and stuck the other end into the dirt next to my Van, for the same result. When I next did an Auto search I was getting 5x as many stations from quite distant locations.
Later on I found the Antenna connector into the back of my Sony Stereo head unit was compromised. When patched it was better, but the grounded antenna in the dirt still improved reception.
Last year I finally replaced the antenna. Its base is supposed to be well grounded to the metal body, and I found this mating area on the underside of the body panel had grown brocolli and cauliflower like a battery terminal.
Reception much improved when I installed an aftermarket 'whip' antenna, and I figure it was the new clean ground where it attached to the body, as with antennas, usually the larger the better, and this new antenna was 16 inches tall compared to the stock Stainless steel 3 footer.
Also, see if turning off LED lights helps reception. They are electrically noisy, especially those with a wider voltage range like 12 to 24V. Ham radio operators hate noisy LED's.
I have several LEDs which will knock out strong TV stations. Twisting the wires to the LEDs tightly in a drill can help, so can the snap on ferrite chokes.
http://www.amazon.com/gp/product/B0...d_t=201&pf_rd_p=1944687542&pf_rd_i=B009U14CVI
I set up my old TV in my workshop and use some 12-24v mr11 LEDs which completely know out an actual channel 8. When I twisted the wires from power source to light tightly in the drill and snapped on ferrites as close as possible to LEDs and to 12v power supply, channel 8 came back in at full strength.
So often it is not about improving reception, it is counteracting nearby sources affecting reception, or a bad ground, or some combination.