What is a disadvantage of the "rubber duck" antenna supplied with most handheld radio transceivers?

The primary disadvantage of the "rubber duck" antenna, which is commonly supplied with handheld radio transceivers, is that it does not transmit or receive as effectively as a full-sized antenna. This is primarily due to its shorter length and design, which limits its performance in terms of gain and range.

Full-sized antennas are generally more efficient because they can provide better matching to the radio frequencies typically used in communication, allowing for stronger signal transmission and reception. In contrast, shorter antennas like the rubber duck may lead to more losses and less effective signal propagation, particularly at greater distances or in environments with obstacles that can interfere with radio waves.

The other options may present lesser issues but are not as significant as the performance gap between the rubber duck antenna and larger, better-designed antennas that maximize effectiveness. Circular polarization might be beneficial in certain situations, but this is not a general disadvantage of the rubber duck itself. Similarly, while losing the rubber end cap could cause practical limitations, it does not inherently affect the antenna's performance when intact. Thus, the most significant disadvantage is the reduced transmission and reception capabilities.