Dear Adel, Thanks for your explanation. I realized that 'trapz' is used for the transmission integral over all ky points, that can be a key to check if I got a meaningful k-resolved transmission. Moreover, I find your previous discussions about angle-resolved transport (https://mail.python.org/archives/list/kwant-discuss@python.org/message/V2PM6JNKOA6SIXBHCVJ7QMETTUSS4QZ5/), from which I learned a lot. Thank you again for your help !
Sincerely Yours, Jiaqi