Guess you want to making a one port calibration and measure your DUT S11 response, you could remove the 2.4mm adaptor from the cable and calibrate plane will be at your cable connector. The 2.4mm adaptor should be very low loss and good return loss since it's an adaptor for same type connector but differ porlority. If the expected DUT S11 is higher enough than your adaptor S11,like 10dB higher, then this method will introduce very low measurement error to you.