chip impedance value having on effect on antenna results

[touseef hayat]

a mono band rfid antenna is signed which is supposed to resonate at a particular frequency. chip is assigned lumped port but varying impedance values of chip does not make any difference. moreover antenna is not resonating at that particular frequency. please help.

thanks

 

[WimRFP]

Resonance (when looking from a 50 Ohms port) is not required for the chip as the chip doesn't show a real load to the antenna. You need to have an almost conjugated match.

If the chip has an input impedance at operation of 40-j60 Ohms (just an example), your antenna should present 40+j60 Ohms to the chip to have a good power match. So when you simulate your antenna it should have Z = 40+j60 Ohms.

40-j60 Ohms is not best match for a 50 ohms based system, but for this example chip it is.

 

[touseef hayat]

but as i mentioned that there is no change in result at any value of impedance i mean chip impedance is not effecting results

ok just tell me how do we assign impedance to the chip. i am doing it this way

assign boundaries --> impedance --> assign values and ok

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here is my antenna design

 

[WimRFP]

I don't know your software, so I don't how it treats complex source impedances.

Be careful assigning complex impedances to sources. If you do, check some simulations with manual calculations.

It is normal that when you change the source impedance that drives your antenna that, the antenna impedance doesn't change. I am still unsure about what you are doing with the antenna impedance and chip input impedance.