[SOLVED] Question about small ground effect in antenna design

[Guest]

football ground plane

in some antenna design, small ground was used. So is it possible that a pole plane of gain or radiation patter will be produce at the azimuth plane of ground plane. For GTD, some field will deflect to below ground, so i wonder the field at the azimuth plane theta=90 will not be a pole. Is it right?

 

[g86]

Re: effect of small ground

Could not understand..can you please rephrase it.
:!: :idea: :?:

in some antenna design, small ground was used. So is it possible that a pole plane of gain or radiation patter will be produce at the azimuth plane of ground plane. For GTD, some field will deflect to below ground, so i wonder the field at the azimuth plane theta=90 will not be a pole. Is it right?

 

[Guest]

Re: effect of small ground

Could not understand..can you please rephrase it.
:!: :idea: :?:

In design of microstrip patch, infinite ground plane is always assumed, and in measurement a quasi-infinite ground plane is used. But in some cases, such as antenna in handset, the dimension of ground can compare with radiation patch, so there may be some power/field will diffracte from the radiation to the below of ground plane(such case may be calculated by GTD method(Geometrical Theory of Diffraction)). Ok, so i want to know how much power can diffract to below ground, and how to perform of the field in azimuth plane(parallel to ground)(Because in the case of infinite ground, tangential electric field on ground plane will be diminished, but for small ground it will not be. So i am interested in the radiation pattern in parrallel to ground).

in some antenna design, small ground was used. So is it possible that a pole plane of gain or radiation patter will be produce at the azimuth plane of ground plane. For GTD, some field will deflect to below ground, so i wonder the field at the azimuth plane theta=90 will not be a pole. Is it right?

[/quote]

 

[g86]

Re: effect of small ground

I had simulated patch antenna with finite GND using IE3D I i get it back I'll surely post it here. The modelling is little bit tricky and tedious and I remember it generated a large 3D mesh and took enough time. As I remember for a patch antenna with a GND of 6h extention at all sides gave me approximately 17 dB front to back ration. I also performed a quick experiment and obtained 14.5 dB front to back ratio. There will be a significant back radiation for both E-plane and H-plane.

In case of the patch antennas used in the mobile phone..many types of antennas are used. They are normaly shorted, with slot to make compact size and suitable for multiband and even sometimes the ground plane is so small the the difference between front and back radiation is smaller than 3 dB.

:!: :idea: :?:

Could not understand..can you please rephrase it.
:!: :idea: :?:

In design of microstrip patch, infinite ground plane is always assumed, and in measurement a quasi-infinite ground plane is used. But in some cases, such as antenna in handset, the dimension of ground can compare with radiation patch, so there may be some power/field will diffracte from the radiation to the below of ground plane(such case may be calculated by GTD method(Geometrical Theory of Diffraction)). Ok, so i want to know how much power can diffract to below ground, and how to perform of the field in azimuth plane(parallel to ground)(Because in the case of infinite ground, tangential electric field on ground plane will be diminished, but for small ground it will not be. So i am interested in the radiation pattern in parrallel to ground).

in some antenna design, small ground was used. So is it possible that a pole plane of gain or radiation patter will be produce at the azimuth plane of ground plane. For GTD, some field will deflect to below ground, so i wonder the field at the azimuth plane theta=90 will not be a pole. Is it right?

[/quote]

 

[Guest]

ie3d

I also used ie3d for simulation. but the calculated pattern at azimuth plane is null. i think this is a bug of ie3d coz field should be existed at this plane if finite ground(small ground) is used. What do you think?

 

[g86]

Re: ie3d

Bag full of bugz are there in IE3D. And also in radiation pattern calculated by IE3D is _ALWAYS_ buggy for infinity GND microstrip antennas. But in your case I feel some thing gone wrong in your modelling.

:!: :idea: :?:

I also used ie3d for simulation. but the calculated pattern at azimuth plane is null. i think this is a bug of ie3d coz field should be existed at this plane if finite ground(small ground) is used. What do you think?