Minimising dimenstions of near fields

[microfielder]

Hi,
How can the length of the near field of a microstrip antenna be reduced?
The wevelength is 403MHz, the microstrip resonates at 1/4 lamda, the substrate has an Er=35.
The near field at the moment is too large, can it be reduced?
Thank you.
Kind Regards.

 

[Scott_PHX_APP]

You say the Er is 35? Seems high, what is the substrate? I could see 3.5, but 35? How close is your impedance matched? Can you give us a bit more info on what you have and are doing, etc.?
Later...

 

[microfielder]

You say the Er is 35? Seems high, what is the substrate? I could see 3.5, but 35? How close is your impedance matched? Can you give us a bit more info on what you have and are doing, etc.?
Later...

I am using Er 35 Zr--O2 to reduce the dimensions of a spiral microstrip antenna. I get an S11 of >-25 dBi with a side feed. The antenna works in the human body and must be insulated from tissue to avoid loading/frequency shift. I assume that if the near field could be as close to the antenna as possible, tissue effects would be minimal.
Can the use of a high Er superstrate cover possibly concentrate the near field enough to make this happen?
Or could alterations to the shape of the spiral make a difference?
Thank you.

 

[Scott_PHX_APP]

Well, you got me on that one. From what you were first talking about, I was thinking you were working on a PC Board. I design PCB's and thought I might be able to help more. Perhaps, if you provide as much info as you can, (what you have now may be enough) some one else here can provide a bit more info. Good Luck, your project sounds interesting...
Later...