Microstip patch antenna (help)

[huseyinemre]

Hello everyone,


I need help with a 3.5 GHz microstrip circular patch. No matter how much I try to design it, the bandwidth is not wide enough to fully cover the n78 band.Even when adding slots, the bandwidth doesn’t increase significantly, and the S11 parameter decreases a lot.


Are there any existing designs for the n78 band that I can use, or what can I do to achieve this?

 

[FvM]

Achievable bandwidth of an antenna is linked to it's size relative to free air wave length. The bandwidth of an electrical small antenna can't be increased above size dependant limit.

 

[huseyinemre]

Thanks, but I still have to ask: Is there any way to make progress without changing the structure?

 

[vfone]

Generally the bandwidth of a normal patch antenna (rectangular or circular shape) is about 5%. This is about 175MHz at n78 frequencies.
Frequency range of n78 band is from 3300MHz to 3800MHz (500MHz).
There are many proposals to increase the patch antenna bandwidth.
From my experience the best option to increase the patch antenna bandwidth, other than using a thick substrate with low Dk which are mandatory, is to use an inset feeding of the patch or incorporating a U-shape slot. Inset feed and U-shape slot cannot be done simultaneous.

https://arxiv.org/pdf/1906.00252

 

[huseyinemre]

Thanks for the reply, I will try redesigning it with the U-slot.I am sort of beginner, so I need to ask: Is it normal for creating slots to significantly change the resonance frequency and S11 parameter?

 

[vfone]

I don't name it "normal" but slots placed on the patch antenna could increase the antenna bandwidth, change the resonant frequency, change the antenna polarization, increase antenna efficiency (by reducing surface wave effects), reduce antenna patch size, change the antenna pattern, etc.