Help me out with a 450MHz PIFA project

[Rainli]

Currently one 450MHz PIFA project is running in my company. The dimension of antenna is 35mm*16mm*7mm. The length of PCB is 80mm. The simulation and pratical test result are both -10dBi gain. It means efficiency is about 10%!!!

Is there anybody have the experience of similar project before? I am looking for kindly help from you.

 

[vfone]

Re: 450MHz PIFA

From the empirical formula that approximates the resonant frequency for PIFA:
Fr[MHz] = 300/(4*(Length[m]+Width[m]))
seems that the resonant frequency for your given dimensions is close to 1.47GHz. This could be the reason of the low gain that you get at 450MHz.
A normal gain for a PIFA should be between 0dBi and 2dBi.

 

[joshuacp]

Re: 450MHz PIFA

Rainli，I also confronted with this problem. I got doubt about your result. If your antenna is PIFA, and the efficiency if 10%, then the gain(dBi)=directivity(dBi)-10log(antenna efficiency)~=5-10=-5dBi. So may be the antenna efficiency of your antenna is less than 10%,or your antenna is other structure, for example the shorted spiral-like printed antenna. Several days ago, I followed a piece of paper(IEEE Antenna and Propagations March 2002:Shorted Spiral-like Printed Antennas), I got all of the parameters of the antenna, and the paper told me that the gain of the antenna is about 0.5dBi, but my simulation with the aid of IE3D is
-10dBi.
The low gain of -10dBi is normal because of the very small volume.
If you have interest, plz contact with me by e-mail: joshuacp@163.com

 

[Rainli]

Re: 450MHz PIFA

Thanks. Is it possible to reach higher efficiency? Is there any speical solution?