Technically speaking, this is a stacked antenna array. It is like cascading one or more vertical dipoles of 1/2 λ length above a regular 1/4 λ vertical monopole antenna. The upper end of the lower monopole drives the lower end of the next upper dipole. However, a phase shift of 180 ° needs to be introduced between the junction of a monopole and an upper dipole. This can be achieved through various methods, but the simplest one is to use a 1/4 lambda long transmission line as a parallel stub and short-circuit it at the far end. This is the required phase shifter. Even if a dipole portion is used above the monopole, it is still an excellent antenna. It has excellent omnidirectional mode in azimuth, large gain, small takeoff angle, and very good DX effect. Adding more than one dipole at the top of the first dipole section can generate high gain, but it may not be practical for high frequencies. However, multi section vertical collinear antennas are commonly used in ultra-high frequencies, especially those with practical dimensions.

　　Vertical antenna is a multi band antenna that cleverly utilizes the mutual induction characteristics between closely spaced conductors. Structurally, this antenna has a normal vertical radiator, and its length is designed to resonate in the lowest frequency band of interest. This is the main driving element, which is fed together with a grounding system or a set of radiators at the bottom, similar to the classic vertical monopole. Several other components that can generate resonance in different high-frequency bands are placed parallel to the driving components at very close distances to achieve tight inductive coupling. When the excitation frequency band becomes higher, the main driving element no longer generates resonance, and the impedance amplitude of the feeding point increases, becoming a passive component. Therefore, the effective parallel load impedance of the inductive coupling element now determines the impedance of the feeding point and reflects the resonant state.

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