how to increase the bandwidth of a microstrip antenna using IE3d

[sameerccs11]

hello i m sameer. i have design a microstrip antenna i m getting very good results but its bandwidth is very low so i want to know how can i increase the bandwidth.
the basic parameters of my antenna is
relative permittivity 2.2
thickness 1.574
tangentloss= 0

i have air above the ground plane and i have made some slots also in it but gain is high but bandwidth is very low.
i m attaching the picture of side view and top view of my antenna and the picture or results also so please anyone help me in increase the bandwidth of the antenna. i will b very thankful too you

 

[WimRFP]

Increasing the bandwidth can be done by increasing the substrate height and/or using multiple radiating or non-radiating resonators.

The first method is relative straight-forward and will give you result with limited amount of iterations. The second method (multiple resonances) requires good skills as creating other resonance (with slots or other patches), mostly affects the first resonance also.

I would recommend you to read a good reference on microstrip antennas, for example: "Compact & Broadband Microstrip Antennas", Kin-Lu wong.

Using a second non-radiating resonator will give you an increase of useful bandwidth (VSWR=2) of almost factor 2.5.

Note that you can increase the BW by introducing loss, but this also reduces the radiation efficiency (hence gain) and that is mostly not desired. Other option is to lower eps.r, but this will result in a larger patch size.
Increasing the bandwidth can be done by increasing the substrate height and/or using multiple radiating or non-radiating resonators.

The first method is relative straight-forward and will give you result with limited amount of iterations. The second method (multiple resonances) required good skills.

I would recommend you to read a good reference on microstrip antennas, for example: "Compact & Broadband Microstrip Antennas", Kin-Lu wong.

Using a second non-radiating resonator will give you an increase of useful bandwidth (VSWR=2) of almost factor 2.5. In your attachment I see you use a parasitic patch above the fed patch. With careful design this should create more bandwidth. I would expect a more or less inversed molar shaped SWR or S11 pattern.

You have already lots of air under the metallic patch, so reducing effective Eps.r is no option.

 

[ferdows]

hi
if u designed antenna was based on other persons research and u did not achieve to them result it may be pertain to your feeding of antenna and the simulation method so change u antenna feed to standard feed
u can reed Compact & Broadband Microstrip Antennas, Kin-Lu wong and Broadband Planar Antennas Design and Applications Zhi Ning Chen and Michael Y. W. Chia
and u can see some stack antenna paper in pier like:
BROADBAND STACKED U-SLOT MICROSTRIP PATCH ANTENNA J. A. Ansari and R. B. Ram
A HIGH GAIN DUAL STACKED APERTURE COUPLED MICROSTRIP ANTENNA FOR WIDEBAND APPLICATIONS N. Ghassemi

 

[sameerccs11]

actually the paper which i m considering is simulated on hfss and i m designing the antenna using ie3d. so may b thats why results are varying

 

[WimRFP]

Hello,

What is the height/lambda ratio for both patches (w.r.t. ground)? When it is basically a halve wave resonating patch (only one current maximum in the middle), the gain should not be that high. Maybe I don't understand your design. What useful bandwidth did you expect (at certain dB(S11)?

Regarding IE3D or HFSS; results should be similar. I used is several times with good agreement between simulations and measurements. You may reduce the meshing size and look for significant changes.

 

[sameerccs11]

the dimension of both the patches are L=53mm and width 79 mm and the dimension of grnd plane is 220mm x 220mm with thickness of 1mm
and i m expecting the bandwidth of abt .27ghz

 

[WimRFP]

Hello,

What is the actual height above the groundplane of the patches itself, as this affects bandwidth signifficantly? What is the absolute maximum thickness for the complete antenna construction?

 

[sameerccs11]

hello
i have stacked form. there are two patches. the thickness of 1st patch from grnd is 12.5
i tell u abt the structure
1st is grnd plane then air of12.5 thickness then a patch then the substrate then again air of 73.5 then a patch then a substrate. i m attaching the one doc file from that u can see top view and side view of the antenna which i have designed.

regards
sameer

 

[ferdows]

hi
in stack and PIFA antenna if u increase the height the bandwidth increase and if u define u antenna dimension like paper and same simulator u first should check u antenna port and simulation

 

[sameerccs11]

thnx for ur suggestion but tell height of what , height of substrate or the height of the patch?

regards
sameer

 

[ferdows]

hi
for UWB antenna the substrate should have low ε i suggest Ta conic RF35 and height should be increase i think 1.58mm is good and the height of stack should be increase too

 

[WimRFP]

Hello Sameer,

Sorry for the confusion. Of importance is the height of the patch (the conductor material) above the ground plane. A low heigth/lambda ratio will result in narrow bandwidth.

 

[ferdows]

hi
i upload for u a part of book that related to stack antenna it can help u and it may useful