Circularly polarized UHF RFID

Hi,
I can not find the same results from the article: Wideband high gain circularly polarized UHF RFID reader microstrip antenna and array.
Can you help me please

zhao2017.pdf

Describe your situations in detail.

This antenna is based on two point feeds where there are 90degree phase shift each other.

Hi Pancho,
My problem is that I can not get the same results.
Please find attached our concept proposal for antenna RFID.

Thank you in advance.