Indoor Random Wire versus Indoor Magnetic Loop Test
In addition to the magnetic loop, I occasionally used a random wire strung throughout the apartment. The wire was about 75 feet in length and I could tune if from 80 to 10 meters against a 12 foot counterpoise. The wire was routed through the apartment for minimum noise pickup. This antenna performed better on 80 and 40 meters than on the higher bands.
One evening I decided to see which antenna performs better on 20 meter PSK31. The first image below shows the waterfall when the random wire is selected. As you can see, it picks up quite a bit of noise. The vertical lines you see in the picture are produced by the computer monitor. Only one signal is visible.
When I switched to the magnetic loop, the waterfall image changed dramatically as you can see below. The monitor interference is hardly noticeable and there are a few more signals visible.
The band was in relatively poor shape on the night I did this test. Under average conditions I see 8 to 12 signals with the magnetic loop on 20 meters.
Of course one has to realize that this test only reflects my situation. However, the test does demonstrate that the magnetic loop is somewhat less susceptible to pick up man made noise, and that it is quite capable of tuning out a noise source.