Why lumped element loading changes the electric length of an antenna?

[Chao Gu]

Can someone theoretically explain why capacitive loading decrease electric length and inductive loading increase electric length?
Are there any papers and books to explain this?
Thanks in advance.

 

[streamlet]

Take a dipole for instance, it can be modeled as a series RLC circuit at its first resonance freq. If additional capacitance is added (as in the case of capacitive loading), the equivalent capacitance will decrease and hence the resonance freq will increase, which can be described as an decrease in the electrical length. The increase in the electrical length in the case of inductive loading can be explained similarly.

 

[Bob60]

Lot of papers, it`s basic staff.