Stacked Patch antenna for 3.2-3.5 GHz band

[naumoves 14]

Hello guys. I am a newbie. Now i'm trying to tune my stack-patch antenna for 3.2-3.5 GHz band in CST. Its current version seems to be able to work good from 3.2 to 4.2 GHz but... VSWR is too high. 

What could you advise to lower it? Are there any effective methods to do it?

- Substrate is lossy FR4.

- CLadding - lossy copper 0.035mm. 

[Admin 2581]

,,,can you post the CST file here...???

[naumoves 14]

Sure! Here it is.

patch_3.3_3.5.cst

[Admin 2581]

,,,where did you get this type of stack-patch antenna,,,???
,,,it seems that it does not have a good impedance on a certain bandwidth and the directivity gain is not good...!!!

,,,the VSWR is not good either...!!!

[naumoves 14]

6 minutes ago, Admin said:

,,, где вы взяли антенну такого типа,,,???
,,, кажется, что у нее плохой импеданс на определенной полосе пропускания и коэффициент усиления по направленности невелик ...!!!

,,КСВН тоже не очень хорош ...!!!

 

I've designed an antenna for 4.990 GHz and 5.200 GHz band (characteristics screen below) and decided to design the same thing for the 3.2-3.5 GHz band. But in this design, I got stuck trying to widen the band and began searching for methods to widen it. I found information about parasitic patches that could help widen the band, and I tried to design one. 

[Admin 2581]

,,,but you can't put 4 directors on one patch...the original antenna has 4 patches...!!!

[naumoves 14]

I thought it should be something like this (image below). 

[Admin 2581]

,,yes, but this is completely different..!!

,,,that's how it should be...

[naumoves 14]

7 minutes ago, Admin said:

,,yes, but this is completely different..!!

,,,that's how it should be...

Thanks a lot! I will try ti figure it out )

[clanon 258]

ALL metal is WAY BETTER (no losses or dielectric shifts) , with 4 patches at 3.5 you'll end up close to 15 dbi (if EVERYTHING is ok) band width might end up to narrow...tho 

[clanon 258]

Adding parasitic patches (close by) would make a new s11 dip (higher or lower than the original) if those TWO dips are close by you'll widen the bandwidth ...(at some s11 expense , s11 goes up , less energy absorbed ) if you stay under -10 and efficiency is good...you are good to go...PS: efficiency is ALWAYS GOOD for me , cause i use STYROFOAM as dielectric...

Edited September 17 by clanon

[naumoves 14]

On 16.09.2024 at 6:16 PM, clanon said:

ALL metal is WAY BETTER (no losses or dielectric shifts) , with 4 patches at 3.5 you'll end up close to 15 dbi (if EVERYTHING is ok) band width might end up to narrow...tho 

Thank you! Have you got any manual of designing this type of antennas in metall? Or can you share a link to it?

[naumoves 14]

2 hours ago, clanon said:

Adding parasitic patches (close by) would make a new s11 dip (higher or lower than the original) if those TWO dips are close by you'll widen the bandwidth ...(at some s11 expense , s11 goes up , less energy absorbed ) if you stay under -10 and efficiency is good...you are good to go...PS: efficiency is ALWAYS GOOD for me , cause i use STYROFOAM as dielectric...

Sorry, could you explain about new dip at s11? Have you got an example of its image?

[clanon 258]

S11 (Return loss) is the energy absorbed or rejected  and it relates to VSWR...from -10 to -20 you have under 2 VSWR, a GOOD antenna...and it should go from the lower frequency you need to the highest (bandwidth)

[naumoves 14]

2 minutes ago, clanon said:

S11 (Return loss) is the energy absorbed or rejected  and it relates to VSWR...from -10 to -20 you have under 2 VSWR, a GOOD antenna...and it should go from the lower frequency you need to the highest (bandwidth)

Thank you, Clanon! But i know about VSWR and return loss dependence  And a know that parasitic patches can widen the band ... but i don't know how they effect on s11 and how i should design them right  

[clanon 258]

same size or smaller and close by...TRY SLOTS on the patchs , that works too

[naumoves 14]

5 hours ago, clanon said:

same size or smaller and close by...TRY SLOTS on the patchs , that works too

Thanks a lot! I'll try!

[clanon 258]

I can't open your cst (i'm using 2020)...

[Admin 2581]

Clanon,try to update the program....https://en.taiwebs.com/windows/download-cst-studio-suite-10756.html

[naumoves 14]

On 18.09.2024 at 4:38 AM, clanon said:

same size or smaller and close by...TRY SLOTS on the patchs , that works too

I think i won this challenge  (with parasitic patches).

[Admin 2581]

,,,this is real impedance...

[naumoves 14]

3 hours ago, Admin said:

,,,this is real impedance...

 

I've tried to design something like plate sma connector with the same dimensions and materials. 

Do you know were i can find pre-built sma connectors for cst with right impedance characteristics?

[Admin 2581]

Why don't you search on this forum, you will find...!!!???

[clanon 258]

On 21/9/2024 at 9:53 AM, naumoves said:

I think i won this challenge  (with parasitic patches).

 

 

 

Check efficiency , usually is poor for FR4...(it hurt RX) , if you are close to 90% it's good enough...imho

[clanon 258]

23 hours ago, naumoves said:

I've tried to design something like plate sma connector with the same dimensions and materials. 

Do you know were i can find pre-built sma connectors for cst with right impedance characteristics?