Determine position of notch or cut

Hi All,

1. I want to know how to decide the notch or cut on the antenna. does that depends on the current density? the higher current density the better will be the radiation(from maxwell equation) if a cut or notch is made there.

2. I am using hfss, to get the notch location only magnitude of current density is enough or do i need to get vector J?

3. to plot J i selected the surface for plotting J and then ran simulation, is this the correct way, because all the results(pattern and s11) are generated after running simulation and then plotted from results --> create modal report ---- ??

Re: determine position of notch or cut

First issue is to decide what you want to do with a notch or cut. Broadband something? band stop? Or what?

Re: determine position of notch or cut

Azulykit said:

First issue is to decide what you want to do with a notch or cut. Broadband something? band stop? Or what?

Click to expand...

i am getting s11 of -10db @ 3 i want to increase that to some lower value like -12 or -15 so yes basically want to increase matching.

someone advised me to check by changing feeding point location as well as by using shorting pins near feeding feeding point. Can you tell what would be right thing to try also how to select this shorting pins locations?

Re: determine position of notch or cut

What bandwidth do you need?
Did you tried to use inset fed? It is much simpler than putting notches/shorting pins.
I recommend inset fed for better s11.
If you need wider bandwidth i recommend aperture coupled patch (very simple, feeding line with approximately A=lambda/4 open, slot approximately B=lambda/2 length, patch WxH on separate substrate with some air gap C). Need only to optimize A,B,C,W,H.

i want to increase bandwidth also. I have an elliptical patch, so if i want to have better bandwidth at a certain frequency then what steps should i follow.
1. plot J at that frequency
2. make notches on the higher J area.
3. can i try keeping a slot on the feedline itself, will that degrade the signal.

now how to decide the shape(circle,square,U slot) of the notches, should be such that it covers max area of high J? or need to multiple iteration

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Azulykit said:

First issue is to decide what you want to do with a notch or cut. Broadband something? band stop? Or what?

Click to expand...

broadband the s11.

Use some kind of sweep over possible notch positions and widths. Use only three points f0-1.5GHz, f0, f0+1.5GHz (to speedup individual simulation iterations). f0 is frequency of interest. Sweep notch offset and width with 0.25mm...0.5mm step. When you find interesting result, all three S11 points are below -10dB, then do finer steps and so on.
I personally do not recommend notches. Try search for: irregularly shaped patch antenna, in my opinion it is better choice. My current favorite is aperture coupled patch, it may be simpler than you think. Try it.

prateek3790, what is your frequency? What bandwidth do you need? Are you constrained by a substrate (Er and height)?
If you find a good notch/cut, try simulation with +-0.1mm deviation in dimensions/position. If S11 degrades significantly, then it is bad notch.

Georgy.Moshkin said:

prateek3790, what is your frequency? What bandwidth do you need? Are you constrained by a substrate (Er and height)?
If you find a good notch/cut, try simulation with +-0.1mm deviation in dimensions/position. If S11 degrades significantly, then it is bad notch.

Click to expand...

patch information: elliptical patch with major axis radius ~11mm and instead of full ground partial ground is present.can not post my design

i changed the feed location as you told i was able to get ~ -15db @ 3 GHz(Thanks a lot), but i wanted broader bandwidth, so wanted to cover 2GHz as well, with the current feed adjustment able to get ~ -12db @ 2.6GHz, but kind of stuck here.

I tried placing a U shaped slot on the patch, but the calculation (one dimension ~ lambda/60) were higher than the dimension of my antenna. I tried normalizing all the calculated lengths to fit it into the design, but this didn't help. so not able to understand which slot is to be placed and where, and of what dimenslon?

Can you change substrate to one with lower Er?
Only elliptical patch? How about other shapes?

Georgy.Moshkin said:

Can you change substrate to one with lower Er?
Only elliptical patch? How about other shapes?

Click to expand...

actually it's an existing patch, i just want to keep one more band.lowering the Er didn't help.