What is a disadvantage of using an antenna equipped with traps?

A trap antenna uses tuned parallel inductor-capacitor (LC) circuits, called traps, to electronically isolate sections of the antenna. This creates a single antenna structure that is naturally resonant on multiple frequency bands. Because the antenna is resonant at multiple frequencies simultaneously, it will readily accept and radiate harmonic signals produced by the transmitter if those harmonics fall within the antenna's higher-frequency operating bands. A simple single-band dipole naturally rejects these out-of-band harmonics because it presents a high impedance to them. Traps do not make the antenna highly directional, nor do they restrict it to a single band, as multi-band operation is their main purpose. They also do not inherently pick up more noise than a standard dipole.