Vertical electric dipole design

GOLAP

Dear Altruist,

I want to know the some steps to design the following model in Feko-

A λ / 40 -dipole is placed vertically at a height of h = 4λ above an infinite electric ground plane. Explore the pattern of this arrangement with FEKO using a perfect infinite ground plane. Use thin wire segments and an operating frequency of f0 = 500 MHz. Provide plots with the FEKO output. 

Here how to place a dipole at a height of h = 4λ above an infinite electric ground plane?

Here thin wire segment means what?

To observe the pattern nulls well, how can I increase the number of samples in the elevation pattern when requesting the far field from FEKO. 

Your response will be highly appreciated.

Thank you. 

Torben Voigt

Hi GOLAP,

For people who have no experience with Feko, I always recommend taking a look at the Getting Started pdf and the Example Guide pdf.

I created your model and recorded a video of it. I think that explains everything. "Thin wire approximation" in Feko means that Feko has a very efficient method for calculating line currents. Wires are assumed to be infinitely thin (radial field is the same everywhere), but of course a kind of virtual thickness is given to calculate impedance correctly.

Best regards,
Torben

GOLAP

Hello Torben,

Thank you for your explanation with video.

It was really useful.

Thanking You,

Golap 

GOLAP

Hello Torben,

I need one more favor.

To put the same antenna parallel to the x-axis  at a distance of λ /square root of 2 ,do I need to change the coordinates only attached with this reply. 

I need to find out the direction of maximum radiation ( θm, φm) ,the nulls of the pattern in the ϕ = 0 plane.

Need your suggestion. 

Thanking You,

Golap 

 

GOLAP

GOLAP said:

Hello Torben,

I need one more favor.

To put the same antenna parallel to the x-axis  at a distance of λ /square root of 2 ,do I need to change the coordinates only attached with this reply. 

I need to find out the direction of maximum radiation ( θm, φm) ,the nulls of the pattern in the ϕ = 0 plane.

Need your suggestion. 

Thanking You,

Golap 

 

Hello Torben,

I solved the parallel to the x-axis issue.

May I expect your helping hand how to determine

the direction of maximum radiation (θm, φm) and the nulls of the pattern in the ϕ = 0 plane for such dipole parallel to the x-axis.

 

Thanking You,

Golap

GOLAP

Hello Torben,

Solved the parallel issue to the x-axis.

Would you please guide me how to get the direction of maximum radiation ( θm, φm) ,the nulls of the pattern in the ϕ = 0 plane from simulation ( postfeko).

Need your suggestion. 

Thanking You,

Golap 

 

Torben Voigt

Hi Golap,

I think I would make a Cartesian surface plot of the gain. There you can see the distribution over all angles quite well:

You may also use the "Advanced Field Processing" macro. With this you can easily find the maximum (or minimum etc.) of the Gain. BUT you will not know where it is.

Best regards,
Torben

Torben Voigt

Hi GOLAP,

Due to the dipole length of only lambda/40, there will probably only be a single wire segment after meshing. I would recommend using a local mesh on the wire with e.g. dipole_length/5.

Best regards,
Torben

GOLAP

Hi Torben,

I can not open your file.May be it is the issue with version I am using Feko 2021.2 and 2022.3.

However after changing the dipole length .02*lambda with a height of .707*lambda above the infinite ground plane I am getting the pattern attached with this reply. May be from here we are getting some idea where null can occur.

I tried to use advanced field processing option. Nothing coming up as like as you should me. 

I need some suggestion (may be with a video file if possible ) how to find direction of the maximum radiation ( θm, φm) , maximum directivity, the nulls of the pattern in the ϕ = 0 plane from simulation ( postfeko).

 

Thanking You,

Golap 

GOLAP

Hello,

I think I have almost solved the problems.

Thank you.

Torben Voigt

GOLAP said:

Hello,

I think I have almost solved the problems.

Thank you.

Hi GOLAP,

Good to hear. Let us know if you need further assistance.

Best regards,
Torben

GOLAP

Torben Voigt_20420 said:

Hi GOLAP,

Good to hear. Let us know if you need further assistance.

Best regards,
Torben

Hi Torben,

I hope my message will find you well.

I was looking for some guidance regarding following problem: 

In the optimization of a dipole antenna using FEKO’s simplex search method where parameter to be optimized is the dipole length L, could you please help me to know- "how can I formulate the objective (or cost) function (If possible please inform me what does it mean by objective or cost function). How can I Illustrate the progress of the optimization process by plotting the dipole length L vs. iterations and the objective function versus iterations".

Your detail response will be highly appreciated.

Thanking You,

Golap 

Torben Voigt

GOLAP said:

Hi Torben,

I hope my message will find you well.

I was looking for some guidance regarding following problem: 

In the optimization of a dipole antenna using FEKO’s simplex search method where parameter to be optimized is the dipole length L, could you please help me to know- "how can I formulate the objective (or cost) function (If possible please inform me what does it mean by objective or cost function). How can I Illustrate the progress of the optimization process by plotting the dipole length L vs. iterations and the objective function versus iterations".

Your detail response will be highly appreciated.

Thanking You,

Golap 

Hi GOLAP,

Please see attached video showing how to do it. Here I minimise s11 by changing L. In POSTFEKO I visualise L vs. optimisation run number and s11 vs. optimisation run numberNote, there should be optimisation examples in the Example Guide as well.

Best regards,
Torben

GOLAP

Torben Voigt_20420 said:

Hi GOLAP,

Please see attached video showing how to do it. Here I minimise s11 by changing L. In POSTFEKO I visualise L vs. optimisation run number and s11 vs. optimisation run numberNote, there should be optimisation examples in the Example Guide as well.

Best regards,
Torben

Hello Torben,

Thank you for the explanation with video. I also tried with similar fashion. I was confused whether optimization run number and the iteration are the same thing for Feko or not.. Now I got the idea from your video it is the same thing.

One question regarding this issue is- in the trace option "I" means we are selecting length in the y axis?

Additionally, May I know what is the objective function(cost function)? I have to plot objective function vs iterations.

Thanking You,

Golap

Torben Voigt

Hi Golap,

Yes, at one point in the video at 2:14 I select "l" as Trace, which corresponds to the variable L from the optimization (Feko is not case-sensitive). At 2:37 I then select "search1.goals.impedancegoal1" as Trace, which corresponds to the goal defined in CADFEKO (minimize S11). I think this is what you mean by objective function(cost function).

Best regards,
Torben

GOLAP

Torben Voigt_20420 said:

Hi Golap,

Yes, at one point in the video at 2:14 I select "l" as Trace, which corresponds to the variable L from the optimization (Feko is not case-sensitive). At 2:37 I then select "search1.goals.impedancegoal1" as Trace, which corresponds to the goal defined in CADFEKO (minimize S11). I think this is what you mean by objective function(cost function).

Best regards,
Torben

Thank you for your explanation.

Please take care.

Thanking You,

Golap