About short antenna ?

[pfijk]

Dear friends


The best length for resonance on dipole is λ/2 ,

but short dipole could be used λ/10 .

We know that performance for dipole in λ/2 is better .

In reality , we often need short dipole for mechanical design .

The short dipole and λ/2 dipole can has the same resonance frequency .

How can it do that ? (the same resonance frequency for short dipole and λ/2 dipole)

The physical structure is needed for resonance .

Why is the length for short dipole is enough to resonance ?

Thanks for any instruction .

 

[flatulent]

The shorter antenna has a real part approximately equal to the ratio of its length divided by the quarter wavelength and the whole ratio squared. It is also capacitively reactive. This is why an inductor is placed in series with it.

 

[pfijk]

I know the short antenna is capacitive .

My question is

The short dipole and λ/2 dipole can has the same resonance frequency .

How can it do that ? (the same resonance frequency for short dipole and λ/2 dipole)

The physical structure is needed for resonance .

Why is the length for short dipole is enough to resonance ?

Or additional matching impedance is needed for this case to compensate .

Thanks a lot .

 

[Beijing]

You may try meander line antenna.