How can I improve the gain for a patch antenna?

height of antenna increases the gain

How can I improve the gain for a patch antenna ,it is fed by a Coax and shorted to the ground?

Width W=20.2 mm and Length L=6.6 mm

Resonant frequency 2.45 GHz and the substrate is FR4-epoxy ε=4.4

gain enhancement

to increase the gain out of one single patch.u need to match it properly.

or u can use parasitic patches to increase the gain,or array of elements can do.

hope the answer to the question.

if not let me know

sajid mohammed.

Re: Gain Enhancement

A nice little tool I like to use is Microwave Office which will allow you to import your design variables in an .emp file and then run an optimization on them, this will be much faster than changing geometry and rerunning every time. For instance, I used it to optimize my VSWR by changing R L and C values for several lumped ports. It took about 3 minutes for roughly 3000 runs which, of course, would be ridiculous in HFSS. I hope this helps

Re: Gain Enhancement

Increase groundplane so that beamwidth will reduce and gain will increase.

I think parasitic patch will increase bandwidth not gain?Please crosscheck.

Parasitic radiators increase directivity(gain) in yagi antenna.But i've doubt in case of patch antenna.

regards,
balaguru.

Re: Gain Enhancement

Hello,

Trying to solve this problem, i've added air layer (air height =6 mm) between the ground and the substrate where the antenna is laying,i've added also 2 other patchs seperated by a gap of 0.2 mm to have an array, but always i get a bad gain (negative one) and the coax feed becomes more inductive so it shifts my zero order resonance frequency.

What do you suggest as solution and thanks for all of you.

Re: Gain Enhancement

MrElec said:

Hello,

Trying to solve this problem, i've added air layer (air height =6 mm) between the ground and the substrate where the antenna is laying,i've added also 2 other patchs seperated by a gap of 0.2 mm to have an array, but always i get a bad gain (negative one) and the coax feed becomes more inductive so it shifts my zero order resonance frequency.

What do you suggest as solution and thanks for all of you.

Click to expand...

Patches you have added are parasitics, not array.
I think you should refer
Compact and Broad Band Microstrip antenna by Kin-Lu-Wong.
Which gives some ideas of increasing bandwidth and gain.

regards,
balaguru.

Re: Gain Enhancement

MrElec said:

How can I improve the gain for a patch antenna ,it is fed by a Coax and shorted to the ground?

Width W=20.2 mm and Length L=6.6 mm

Resonant frequency 2.45 GHz and the substrate is FR4-epoxy ε=4.4

Click to expand...

what is the antenna height you use here? are you assuming PEC for the patch, or realistic materials like copper with finite thickness, or finite conductivity boundary condition?

if you are using realistic materials, like copper, then I advise you to increase your antenna height. if the antenna is very conformal, then the currents on the antenna are much higher. higher currents lead to higher losses due to finite conductivity and end up with bad gains. if your antenna height is fixed, there isn't too much to do.

fr4 is a cheap but quite lossy substrate. i think you won't change your substrate? if you are free to choose, select a substrate with smaller tangent delta.

another option is to select a bigger ground plane under the substrate...

Re: Gain Enhancement

Hi friends,

thanks for the help.

what is the antenna height you use here? are you assuming PEC for the patch, or realistic materials like copper with finite thickness, or finite conductivity boundary condition?

Click to expand...

The antenna height is 1.52 mm and i'm assuming PEC for the patch and the ground but copper for the via.

if you are using realistic materials, like copper, then I advise you to increase your antenna height. if the antenna is very conformal, then the currents on the antenna are much higher. higher currents lead to higher losses due to finite conductivity and end up with bad gains. if your antenna height is fixed, there isn't too much to do.

Click to expand...

Higher currents are concentrated around the via and with large microstrips lead to high conductivity loss wich results in very bad gain.

fr4 is a cheap but quite lossy substrate. i think you won't change your substrate? if you are free to choose, select a substrate with smaller tangent delta.

Click to expand...

Yes i know that FR4 substrate is a bad one due to it's high dielectric loss but i've no choice my supervisor want me to built rocket from stones. ,on reality i'm working on resonant antenna designed by CRLH structures based on Transmission line approach, have a look to Mr Caloz and Itoh works.

When i've added an air layer between the substrate and the ground, i've noticed a shift in resonant frequencies and a better gain, these are "good news" but the "bad" one is, the lose of a resonant mode.

Any help or idea.

Added after 6 minutes:

If you want to have a lookt o my HFSS project i can upload it.

Re: Gain Enhancement

nwittema said:

A nice little tool I like to use is Microwave Office which will allow you to import your design variables in an .emp file and then run an optimization on them, this will be much faster than changing geometry and rerunning every time. For instance, I used it to optimize my VSWR by changing R L and C values for several lumped ports. It took about 3 minutes for roughly 3000 runs which, of course, would be ridiculous in HFSS. I hope this helps

Click to expand...

Helo all

I have designed a inset feed patch antenna in HFSS. Can I use Microwave office to optimize my design.

Thanks