Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.
It is easier to understand with a bit modified logical thinking.
For a electrical short monopole antenna (<0.25 lambda), is it the opposite, antenna size grows if components are added.
A capacitive top-load increase a monopole antenna length, both electrical and physical.
Measuring a short monopole antenna impedance without any top-cap shows that antenna load at bottom feeding point is somewhat capacitive.
To compensate for that reactive load can a serial inductor be inserted at bottom of antenna.
If compensating instead is done 0.25 lambda away from this inductor location will a inductor become transformed to capacitor.
Top of the somewhat short monopole antenna is almost at that distance from bottom coil location, 0.25 lambda => at this location should a capacitor be placed to act as a bottom coil.
For same reason do a top capacitor not work very well as tuning element for a real short monopole antenna as the short antenna length is too short to transform top capacitor load to a inductive bottom load.
" It functions as a capacitively top-loaded monopole antenna; " I thought it was a good example, and the article provides further links on the subject.
It seems to throw more light on the subject then your contribution?
Frank
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.
