 This type of antenna is often used over a wide frequency range, e.g.100–500 MHz, and over this range its performance is poor, but in many mobile radio applications there is sufficient excess signal strength to overcome any deficiencies in the antenna.From these rules, one can surmise that it is possible to design a rubber ducky antenna that has about 50 ohms impedance at its feed-point, but a compromise of bandwidth may be necessary.