patch array antenna problem

[ms1234]

I am designing patch array antenna.
For the 16 and 64 elements patch array antenna in Unii band, it is very fortune, I finished my work within a month. and VSWR is under 1.3 @ 5.1GHz - 5.8GHz.
But for 2.4GHz, I can't find a good solution. this is because all simulation tools that I have used give the result very different with mesurement.
So I use "cut and try" method to find out the solutions, and it easy to match all elements to 50 Ohms in UNII band.
But in 2.4GHz, simulation still give the result different with the pratical one,
but I need match all elements by 100 Ohms.
Simulation can't give a good result, "cut and try" can't do 100 Ohms.
Any body can help!

ms1234

 

[Gakusei]

Can you PM me a copy of your test results in phase and amplitude or complex form if possible? It sounds as if you have a resonance in your array. It would also be good if you can send me a sketch of your antenna and its distribution system.

These occur when the mutual coupling and distribution paths become n x halfwave long. These may not show up in your simulation. It may be that a small change in line lengths will cure the problem.

 

[Lupin]

What type of e.m. softwares did you use?
Can you give me more informations or a sketch of your antenna?
I can use my softwares and help you much better....

Regards

Lupin

 

[ms1234]

For 2.4GHz antenna, I just start it so I haven't build array model, only single element available.
I use ie3d, ensemble and cst mws all give different result!
If possible, I will build 4 and 16 elements patch array antenna.
here is the ie3d *.geo

9
9.9933333333e-007 1 5.0000000000e+000 1 1

3.0000000000e+000 2 5 1 1.0000000000e+006 5.0000000000e+002
0.0000000000e+000 1.0000000000e+000 0.0000000000e+000 1.0000000000e+000 0.0000000000e+000 4.9000000000e+007 0.0000000000e+000 0 0
7.9000000000e+001 1.0000000000e+000 0.0000000000e+000 1.0000000000e+000 0.0000000000e+000 0.0000000000e+000 0.0000000000e+000 0 0
1.1000000000e+002 4.5000000000e+000 -2.0250000000e+001 1.0000000000e+000 -2.0000000000e-002 0.0000000000e+000 0.0000000000e+000 0 0
3.6000000000e+002 1.0000000000e+000 0.0000000000e+000 1.0000000000e+000 0.0000000000e+000 0.0000000000e+000 0.0000000000e+000 0 0
3.8000000000e+002 4.5000000000e+000 -9.0000000000e-002 1.0000000000e+000 0.0000000000e+000 0.0000000000e+000 0.0000000000e+000 0 0
3.9370078740e+016 1.0000000000e+000 0.0000000000e+000 1.0000000000e+000 0.0000000000e+000 0.0000000000e+000 0.0000000000e+000 0 0
7.8740157480e-002 1.0000000000e+000 0.0000000000e+000 1.0000000000e+000 0.0000000000e+000 4.9000000000e+007 0.0000000000e+000 0
1 1
-9.8000000000e+002 -9.8000000000e+002 2.1658000000e+003 1.9600000000e+003 1.0000000000e-001 10
1
0 0 0 0 30 30 0 0 0.0000000000e+000 0 0.0000000000e+000 0
0.0000000000e+000 0.0000000000e+000 0.0000000000e+000 0.0000000000e+000
3 6 1 0
0.0000000000e+000 1
7.9000000000e+001 0
1.1000000000e+002 0
3.6000000000e+002 0
3.8000000000e+002 0
4 5 1.4142298350e+002 6.2831853072e+000 0.0000000000e+000 1
4 0 10 4 1
-7.7500000000e+002 -7.7500000000e+002 3.6000000000e+002 0
7.7500000000e+002 -7.7500000000e+002 3.6000000000e+002 0
7.7500000000e+002 7.7500000000e+002 3.6000000000e+002 0
-7.7500000000e+002 7.7500000000e+002 3.6000000000e+002 0
4 0 10 3 1
8.7500000000e+002 -5.8500000000e+001 1.1000000000e+002 0
1.0000000000e+003 -5.8500000000e+001 1.1000000000e+002 1
1.0000000000e+003 5.8500000000e+001 1.1000000000e+002 0
8.7500000000e+002 5.8500000000e+001 1.1000000000e+002 -1
6 0 10 3 1
-8.7500000000e+002 -8.7500000000e+002 1.1000000000e+002 0
8.7500000000e+002 -8.7500000000e+002 1.1000000000e+002 0
8.7500000000e+002 -5.8500000000e+001 1.1000000000e+002 -1
8.7500000000e+002 5.8500000000e+001 1.1000000000e+002 0
8.7500000000e+002 8.7500000000e+002 1.1000000000e+002 0
-8.7500000000e+002 8.7500000000e+002 1.1000000000e+002 0

0 0

Just cut it and save as *.geo. I have tried, no problem to do this.
Thanks!

 

[Lupin]

I'm sorry but I uninstalled IE3d...I use Ensemble, CST and HFSS.
Try to describe your strucutre and I'll design it with my softwares.
Anyway, try to check your gridding mesh. The results are strongly affected. For 2.4 GHz I suggest you to use an adaptive mesh from 2 to 3 GHz. Then try to use a finer mesh and check the converge of the results.
You might use a frequency simulation range for separate working frequency bands....

Tell me if you've still problems, otherwise describe here your structure.

Regards
Lupin

 

[ms1234]

The structure is
layer 1 : ground plane
layer 2 : 79 mil, air.
layer 3 : 31mil FR4 pcb (will be reduce to 20 mil next time), with
1750mil x 1750mil patch, above it, edge feeded.
layer 4 : 250 mil, air
layer 5 : 20 mil roger 4003 pcb with 1550 mil x 1550 mil copper plate.
(will be changed to 20 mil FR4 after I get it)

I have found an error during measurement so the result is very closed with ensemble result, but still different with the others (don't know why).
so I changed patch size to 2000x2000 mil.
Next week I will try to made a real one for measurement.

thanks for Lupin's and Gakusei's help.

ms1234

 

[loucy]

Can you post a figure comparing the results? Project files would be even better.

 

[ms1234]

I will post it on monday when I go back to the lab. Thanks!

 

[ms1234]

Today I change the size of patch, then ensemble is no longer match the measurement, don't know why?
The attachment is two ensemble projects and it result (only proj 1).

ms1234