[Help]About dielectric covering for microstrip patch antenna

Hi everyone,
I meet questions about dielectric covering for microstrip patch antenna,the Er of the covering is from3~4,topic value is 3.5,and tan(delta)=0.005.when it is covered on
a microstrip antenna which is resonance on 2GHz without covering,but when the patch is covered,I cannot find resonace point from 1.8~2.2GHz!And the pattern is poorer than no covering!Who can tell some rules about it?and offer some papers about it,I need them exigence.
Thanks!Regards
CaoCao

Hi,

I think the resonant frequency goes down well below 2GHz (would not be surprised to find it around 1GHz but cannot be foretold). It is sure the general effect of coating an antenna with dielectric material is to make it look like longer in effective length as if you had enlarged its physical sizes to get a lower resonant frequency.

There is an interesting article on this but tricky to see it. If you write the words [ effect dielectric coating antenna ] into google the first hit is entitled Dielectric Constant at the url www.ee.surrey.ac.uk/Personal/ D.Jefferies/antennexarticles/diecon.htm but when I go there the page cannot be found. If I use google's cache version on this url, then the page comes with useful text on your topic but without pictures.

unkarc

Hi unkarc
Thanks for you advices!Can you offer me some papers about it? I want to know it deeply
Regards!
caocao

Hello !
At my experience coating have no so strong effects as you describe there, at 2GHz resonant shifted m.b to 50 MHz down.
How mach is the thikness of coating dielectric in your case ?

Hi Caocao,

Although I like the topic of antennas (have had practical experience in building Yagis, rhombic and some typical amateur radio antennas like dipoles or verticals), unfortunately I am not an expert on dielectrically loaded antennas.
So the homework of searching through the internet remains mainly for you, I cannot show you off-the-shelf articles

Nevertheless, see url
http://www3.interscience.wiley.com/c...00888/ABSTRACT

Regards
unkarc