microstrip antenna simulation with IE3D

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indiaco

Joined: 10 Apr 2004
Posts: 39
Location: Down South...

06 May 2004 2:45 ie3d microstrip antenna

hi all, i want to know if it´s resonable to have a 9 dBi gain with a single patch antenna, inset feed, air dielectric. Simulated with IE3D with infinite ground plane and a thin metal thikness added to the patch.
I find the gain somehow high for one patch, is this right ?
forgot to mention the frec band= 2,4-2,48 GHz
Thanks a lot.
NICO

mamali

Joined: 29 Apr 2004
Posts: 387
Helped: 4
Location: between hell and heaven

06 May 2004 14:20 microstrip antenna simulation

What is the directivity?
If you use a finite ground plane, the dirctivity and thus the gain will being more. thus it should be in real a MPA with about say 11dBi directivity. I think you have some problem with modeling.

urs, murti

eirp

Joined: 11 Dec 2001
Posts: 639
Helped: 9
Location: Phase center

06 May 2004 14:26 antenna simulation ie3d

Hi!

Classical approach for rectangular patch operating at fundamental TM01 mode concerning 2 slots to be radiating:

slot <--> dipole --> ~2.15 dBi
they are two --> +3dB
radiating only to 1/2 of space --> +3dB
--------------------
roughly ~8dBi
so 9dBi is reasonable

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indiaco

Joined: 10 Apr 2004
Posts: 39
Location: Down South...

06 May 2004 17:26 design microstrip antenna with perfect vswr

mamali & eirp thanks for your answers....

mamali, i have simulated my antenna with infinite ground plane. When i thought the results were good enougth (vswr=1.1 & gain ~ 9dBi), i started simulating with finite gruond plane (allways folowing IE3D help file).
The result didn`t change much for a slightly big ground plane (14x14cm).
The strange thing is that the directivity has the same value as the gain, thing i don´t like very much....
what problem do you think i may have with the simulation? Cause it ´s not such a big deal to draw the antenna or set the basic parameters.

Thanks a lot.

Nico.

mamali

Joined: 29 Apr 2004
Posts: 387
Helped: 4
Location: between hell and heaven

06 May 2004 17:35 ie3d microstrip antenna

dear indiaco,
I think eirp is right. anyway, you should considering the bandwidth. you have an about 100% antenna efficiency, so I think you have a narrow bandwidth. yes, with a naroow bandwidth its possible to have a perfect match, and then directivity=gain.

urs, murti

mamali

Joined: 29 Apr 2004
Posts: 387
Helped: 4
Location: between hell and heaven

06 May 2004 23:00 2.4 ghz microstrip antenna simulation

indiaco wrote:

Dear indiaco,
I forget to mention some points. first, what application do you have, and then how do you feed it? I can further guide you if you are looking for a broadband patch.

rgrds, murti

divan

Joined: 01 Mar 2002
Posts: 91
Helped: 2

07 May 2004 3:11 stacked rectangular microstrip antennas ie3d

Hello!
really say u can obtain 7-8 dBi from a single patch, mot more in practice if take efficiency in attention.
rule will be as "lower placed patch > higher gain > narrower band".

mamali

Joined: 29 Apr 2004
Posts: 387
Helped: 4
Location: between hell and heaven

07 May 2004 18:11 simuler avec ie3d

divan wrote:

Hello!
really say u can obtain 7-8 dBi from a single fix, mot more in practice if take efficiency in attention.
rule will be as "lower placed fix > higher gain > narrower band".

Dear divan,
I really do not undrestand what you mean by "lower placed p a tch". if you mean, thiner substrates, then i think it has no important effect on gain, but it really lowering the impedance bandwidth. however, efficiencies of more than 90% in practice was achieved, even in a wide band. please especify carefully your means guys Smile

.

regards, murti

divan

Joined: 01 Mar 2002
Posts: 91
Helped: 2

08 May 2004 5:16 microstrip antenna- location

Sure , we are speaking about air dielectric , so i meant thiner space.
thanx

indiaco

Joined: 10 Apr 2004
Posts: 39
Location: Down South...

09 May 2004 21:18 ie3d, gain

dear mamali & others:

the antenna is a single pa.tch inset feed with a 50 ohm microstrip (or so i think), h= 6 mm(substrate thickness). I haved followed the Balanis book to design the patch and feedline.
I have heard that inset feed is not the best way to do this, why is this ?
The simulated bandwidth is enough to cover the 2,4 GHz ism band, the vswr is acceptable. My intention is to design an array, question is should i go for stacked patches or a fix array ?

thanks , nico.-

mamali

Joined: 29 Apr 2004
Posts: 387
Helped: 4
Location: between hell and heaven

09 May 2004 21:51 2.4ghz hi gain microstrip antenna

indiaco wrote:

dear mamali & others:

the antenna is a single pa.tch inset feed with a 50 ohm microstrip (h= 6 mm). I haved followed the Balanis book to design the fix and feedline.
I have heard that inset feed is not the best way to do this, why is this ?
The simulated bandwidth is enough to cover the 2,4 GHz ism band, the vswr is acceptable. My intention is to design an array, question is should i go for stacked patches or a fix array ?

thanks , nico.-

You mean 2.4GHz~2.483GHz ? it is a relatively narrowband application, and you can use inset feed with the relatively thick substare you already have. but the inset feed has namerous disadvantages, and if you need a wider bandwidth (or maybe better SWR), you should use other feed methods. however, for such narrowband application, the inset feed is simple, straight forward and easy to manufacture. you better specify the relative permittivity (er) too. u know that lower er gains more bandwidth. and moreover, what is the neede -3dB angel? if it is narrower than standard (about 60~70 degrees), you may use a supperstrate to narrowing the beam and reaching more directivity and gain with a single patch (although to just, say, 1dBi).

+stacked patch often used for widebanding or dualbanding the MPA. i think the structure could not increase the gain.

+if thicker substrates (wich gains higher bandwidths) is used in MPAs, an inductance introduced wich reduce the antenna performance, and even suppress the radiation for a certain thickness. this inductance could not be effectively adressed by inset feed (even methods introduced, but are just fair, and relative to other feeds, are nothing!).

your friend, murti

abdoeng

Joined: 22 Feb 2004
Posts: 685
Helped: 14
Location: EGYPT

12 May 2004 3:20 inset feed +rectangular microstrip+cut width

hi guys,rarely to get high gain with wide bandwidth,i think that u can obtain high gain with narrow band width and vice versa

mamali

Joined: 29 Apr 2004
Posts: 387
Helped: 4
Location: between hell and heaven

25 May 2004 14:00 ie3d microstrip antenna design

abdoeng wrote:

hi guys,rarely to get high gain with wide bandwidth,i think that u can obtain high gain with narrow band width and vice versa

whats the meaning of high gain? 8dBi~5dBi in 20%~50% was achieved with MPAs.

marti

tmau

Joined: 31 Aug 2004
Posts: 8
Location: Hong Kong

31 Aug 2004 17:23 microstrip antena simulator

Try to change the directivity to gain, because directivity doesn't include the antenna efficiency.

For thick microstrip antenna with air dielectric, it is around 8dBi, but the cross polarization might be higher

svarun

Joined: 31 Mar 2002
Posts: 280
Helped: 7
Location: In the warm company of God's most exquisite creation - The Tiger

31 Aug 2004 19:50 microstrip antenna simulation tool

eirp wrote:

Hi!

Classical approach for rectangular fix operating at fundamental TM01 mode concerning 2 slots to be radiating:

slot <--> dipole --> ~2.15 dBi
they are two --> +3dB
radiating only to 1/2 of space --> +3dB
--------------------
roughly ~8dBi
so 9dBi is reasonable

Beautiful , intuitive deductions.However I want to add one comment.There is this problem of the TMo mode surface wave (which has no cut off and ofcourse more modes as frequency rises ) which diffracts off the finite ground plane edges resulting in pattern distortion and reduced directivity.I wonder how much is that.Is there anyway to model that ? I am working on a new geometry of PBG to reduce surface wave propagation.All comments are welcome.

-Arun