dual band antenna help!

[v1p3r32]

Hi all! Currently designing an antenna to perform dual band frequencies of 890 - 960 MHz and 1710 MHz - 1880 MHz. However regardless of the changes I've made, the best I've gotten for s11 is only the first frequency band. The second frequency band is nowhere near my requirement.



The top side of the substrate is the balun feeding the 3 dipoles at the bottom side. dielectric constant at 4.4, thickness at 0.8mm. width of balun is 1.5mm.

this is the s11 result I got.



Hope to receive some advice on my design, it will help alot! thanks.

 

[LORDALEX]

Helllo,
from wha paper you have get this antenna, plz can you post the paper title

 

[hamidrezakarami]

I can not understand that you problem is in design process of dual band patch antenna or simulation of it?

 

[v1p3r32]

Helllo,
from wha paper you have get this antenna, plz can you post the paper title

Hi, I've gotten this design from the following

Modified planar quasi-Yagi antenna for wlan dual-band operations

Chang, Dau-Chyrh (Dept. of Electrical Engineering, Da-Yeh University, Datsuen-Shiang, Chang-Hua, Taiwan); Chang, Cheng-Bing; Liu, Ji-Chyun Source: Microwave and Optical Technology Letters, v 46, n 5, p 443-446, September 5, 2005

Right now, I have gotten the results but my prof had requested a smaller size of the antenna. Any suggestions? I've increased the permitivity of the substrate to 10.2, but it didn't reduce much. Gonna try meandering now.

 

[LORDALEX]

Hello,
thank your for your answer, i working more less on the same antenna, indeed if you want a small size, i advice you to design a meandered monopole. You could found many example in book "planar antennas for wireless communications" (kin-Lu wong")
If you want i have posted a three design for meandered monopole with a small size. The problem is that i cant found the same response as in paper. If you want you can use and notify me if you will get a good response

 

[v1p3r32]

Hi, where can I get those designs you mentioned? Thanks for the info, I'll look them up

 

[LORDALEX]

Hi
You can found design as attachment in this link
https://www.edaboard.com/threads/276894/

 

[v1p3r32]

I had run several simulations on the meandering design

And this is the best result I can get. My expected is frequency is 925MHz and 1.8Ghz



Hmm anyone has got any suggestions to fine tune the s11 results? Many thanks!