arr_baobao
Full Member level 2
Hi ,
I encounter this difficulty when matching my off the shelf GPS antenna to 50 ohm.
hope someone could tell me whats when wrong and how to debug.
so the original load impedance was shown in the pic below.
i have a "series-shunt-series-shunt" matching circuit before my GPS antenna. series component was replaced with 0 ohm and below are the measured impedance(highlight in yellow).
then i tried to matching the antenna by using series/shunt inductor for my first component. i tried a few value so below are the measured impedance.
then i try to used 2nd component (series/shunt) to try matched it to 50 ohm. but when i place the second component, the impedance just wouldn't move, it just sit at the points almost the same as the first components, i have used the value based on the simulation tools and try a few other value too. i tried 3 set of matching circuit based on the pic i sent above, but all same, it just couldn't matched to 50 ohm when i place the 2nd matching component.
can someone enlighten me what happened in this case. is it some parasitic that causing it not able to match to 50 or close to 50 ohm?
i have follow all the recommend design from the off the shelf GPS, antenna placement, board size, matching circuit layout bla bla bla..
hope someone here can point out the issue or tell me how to debug it.
thanks.
I encounter this difficulty when matching my off the shelf GPS antenna to 50 ohm.
hope someone could tell me whats when wrong and how to debug.
so the original load impedance was shown in the pic below.
i have a "series-shunt-series-shunt" matching circuit before my GPS antenna. series component was replaced with 0 ohm and below are the measured impedance(highlight in yellow).
then i tried to matching the antenna by using series/shunt inductor for my first component. i tried a few value so below are the measured impedance.
then i try to used 2nd component (series/shunt) to try matched it to 50 ohm. but when i place the second component, the impedance just wouldn't move, it just sit at the points almost the same as the first components, i have used the value based on the simulation tools and try a few other value too. i tried 3 set of matching circuit based on the pic i sent above, but all same, it just couldn't matched to 50 ohm when i place the 2nd matching component.
can someone enlighten me what happened in this case. is it some parasitic that causing it not able to match to 50 or close to 50 ohm?
i have follow all the recommend design from the off the shelf GPS, antenna placement, board size, matching circuit layout bla bla bla..
hope someone here can point out the issue or tell me how to debug it.
thanks.