The bandwidth characteristics of a resonant antenna element can be characterized according to its Q, just as one uses to characterize the sharpness of an L-C resonant circuit. However it is often assumed that there is an advantage in an antenna having a high Q. After all, Q is short for "quality factor" and a low Q typically signifies excessive loss (due to unwanted resistance) in a resonant L-C circuit. However this understanding does not apply to resonant antennas where the resistance involved is the radiation resistance, a desired quantity which removes energy from the resonant element in order to radiate it (the purpose of an antenna, after all!). The Q is a measure of the ratio of reactance to resistance, so with a fixed radiation resistance (an element's radiation resistance is almost independent of its diameter) a greater reactance off-resonance corresponds to the poorer bandwidth of a very thin conductor. The Q of such a narrowband antenna can be as high as 15. On the other hand, a thick element presents less reactance at an off-resonant frequency, and consequently a Q as low as 5. These two antennas will perform equivalently at the resonant frequency, but the second antenna will perform over a bandwidth 3 times as wide as the "hi-Q" antenna consisting of a thin conductor.
The bandwidth characteristics of a resonant antenna element can be characterized according to its Q , just as one uses to characterize the sharpness of an L - C resonant circuit . However it is often assumed that there is an advantage in an antenna having a high Q. After all , Q is short for " quality factor " and a low Q typically signifies excessive loss ( due to unwanted resistance ) in a resonant L - C circuit . However this understanding does not apply to resonant antennas where the resistance involved is the radiation resistance , a desired quantity which removes energy from the resonant element in order to radiate it ( the purpose of an antenna , after all ! ) . The Q is a measure of the ratio of reactance to resistance , so with a fixed radiation resistance ( an element 's radiation resistance is almost independent of its diameter ) a greater reactance off - resonance corresponds to the poorer bandwidth of a very thin conductor . The Q of such a narrowband antenna can be as high as 15 . On the other hand , a thick element presents less reactance at an off - resonant frequency , and consequently a Q as low as 5 . These two antennas will perform equivalently at the resonant frequency , but the second antenna will perform over a bandwidth 3 times as wide as the " hi - Q " antenna consisting of a thin conductor .
The properties of a usable radio frequency can be called its?
The properties of a usable radio frequency can be called its ?
Q
Q