There are many shortwave listeners who can't, because of location, infirmity or a unyielding landlord, put up an outside antenna. Yet, for the serious listener, neither choice is completely adequate.
Active antennas are expensive, apt to generate as much noise as signal, and are prone to overload.
Both subject the receiver to intermod, spurious signals and other trash. The Carpet Loop II is an ideal step upward for the listener who wants something better than a random wire but doesn't want the expensive dice roll of an active antenna. To tune the antenna, you turn a switch for best reception. While NO antenna can give a cheap receiver the sensitivity, selectivity, or dynamic range it never had, the Carpet Loop will help you get the last ounce of performance out of your radio. Two years ago, I was using a random wire.