Rubber ducky antenna

It consists of a springy wire in the shape of a narrow helix, sealed in a rubber or plastic jacket to protect the antenna.

The rubber ducky is quite flexible, making it more suitable for handheld operation, especially when worn on the belt, than earlier rigid telescoping antennas.

[7] Rubber ducky antennas are typically 4% to 15% of a wavelength long;[7] that is, 16% to 60% of the length of a standard quarter-wave whip.

Because the length of this antenna is significantly smaller than a wavelength the effective aperture, if 100% efficient, would be approximately:[8] Like other electrically short antennas the rubber ducky has poorer performance (less gain) due to losses and thus considerably less gain than a quarter-wave whip.

They are difficult to characterize electrically because the current distribution along the element is not sinusoidal as is the case with a thin linear antenna.

In common with other inductively loaded short monopoles, the rubber ducky has a high Q factor and thus a narrow bandwidth.

From these rules, one can surmise that it is possible to design a rubber ducky antenna that has about 50 Ω impedance at its feed-point, but a compromise of bandwidth may be necessary.