How to broaden PIFA multiple band bandwidth?

[poey_wong]

pifa bandwidth

Hi all,

I have a problem on broaden all bandwidth (880-960MHz, 1710-1880MHz, 1850-1990MHz, 1920-2170MHz). I use stack method, where i have 4 patches calculate base on fc=c/4(L+W) formula, then i stack them 1 by 1 like staircase with shorting plate in btw. as a result i get 3 bands. however all those band are not wide enough to cover the service frequency in market.

Any1 has any idea?

Thank you!

 

[Alberich]

hi,
Try to play on the width of the shortning pin, or on the position of the feed.

good luck

 

[poey_wong]

hi Alberich,

i have tried before the best result i can get is only max 80MHz (for DCS) and min 20MHz (GSM 900& UMTS), whatelse can i do?

 

[orisapir]

Hi Poey,
You might want to tune the antenna to a lower impedance than 50 ohm, get a "small circle" on the Smith Chart, which you can than move to the 50 ohm with a simple matching circuit. It will probably work for only on frequency, unless if you are using multiple feeds for different frequencies.

 

[ftreqah]

Hi, Plz help me i have a many problem to design a PIFA antenna because i dont know a mathematic formula, help plz