help me check my printed dipole antenna project using HFSS!

material: rogers rt/duroid 5880(tm)

Hi all,

I am a beginner with HFSS. I have its verson 10. Now, I try to design a printed dipole antenna using HFSS. The project have been design alreadly but it seems that there maybe some problems. As can be seen from the S-parameter result figure in this project, the antenna in the project works at quite different frequency (around 5GHz) than that I expected (around 2,4 GHz). Here are some detailed information:
1. The patch: 50mm x 50 mm x 1.475 mm, material: Rogers RT/duroid 5880 (tm)
2. The dipole:
Length of arm: 22 mm
Length of the whole dipole: 46 mm
Width: 3mm
Material: pec
3. Excitation:
Port: Wave port
Type: Using SMA connector which was downloaded from this forum

The project is attached with this message. Please check my project and show me if there is any problem.

Thank you so so much!

Le

printed dipole

Hello

Mismatch of Impedance is there, check the vswr plot, at 2.5Ghz, u r getting 10.22
which is not correct, ideal value is 1, values between 1-2 is accepted.

regards
Avinash

hfss sma project

Hello Avinash,

Thank you very much. Yes, VSWR plot shows that its value at 2.5GHz is not acceptable. But at 4.96 GHz VSWR plot agrees with S-plot. VSWR is equal to 1.10. It means that the antenna works well at 4.96GHz.

The problem which I consider here is that with such printed dipole antenna, theoretically, it should work well not at 4.96 GHz, but at around 2.5 GHz (or even lower). However, the simulation result is not as likely as the theory.

Let analyse the structure of dipole: the overall dipole length is L = 2l = 46mm. Because of printed antenna, the length shoud equal to 0.37λ [1] (instead of 0.5λ as normal dipole suspended in air) [2]. Therefore, λ is about 124mm, then f is equal to 2.41 GHz.

So, what is wrong with my project so that the antenna works at 4.96 GHz which is quite far in comparision with theoretical frequency 2.41 GHz?

Please help me check my project! I am very much thankful to you all!

Best regards

Le


Ref:
[1]: Chi-Yuk Chiu, "Compact three-port orthogonally polarizied MIMO antennas", IEEE antennas and wireless propagation letters, vol. 6, 2007, p 619 - 622.
[2]:

dipole antenna project

Hi all,

Please help me check my project. It is very much important to me.

I am very much obliged to you all!

Le

printed dipole

hello hntko
There are two issues in your project which may cause this strange result.
1. out suface of coaxial line should be set to PEC. It is missed in your design.
2. radaiton boudary. requirement of wavelength/4. For simple,you may choose lump port.
I will upload three files for you later.
1.Mode in 'dipole_lumpot' using a simple lump port without the coaxial line shows a similar result with theory.
2.Model in 'dipole' fix the above two issues based on your original design,but the result is different from the former one with an additional resonant nearly 3GHz.
3. Model in dipole_modify was fixed to find the difference between the above two.I shorten the feeding coaxial line which seems to affect the result. But I can not find the root cause till now.

Added after 5 minutes:

Three files mentioned above. You can run them to see the detailed info.

printed dipole antenna

Hi rachel_zh,

I would like to extend a thank you for your help in showing problems from my project. It means a lot to me.

As you have mentioned, I think that the root problem probably comes from the port. It is because, when I check with your first case: dipole_lumport, the results are quite good.

Actually, as I wrote at the first message, the port used in this project was downloaded from this forum. I did not really check it carefully before making the project. Here is the link of the port (see in sma_model.rar):

Anyone who has used the SMA port for printed antenna, please help me check my project if the using of SMA connector is ok?

Thank you very much all of you - my friends!

Le

Re: help me check my printed dipole antenna project using HF

Hi all,

After a while checking and checking my project, I think that, the problem perhap comes not from the SMA connector, but from the balun part.

People one who have done some projects related to designing balun, please give me some advises for this.

Thank you very much!

Le