Tunable SC(Switched Capacitor) bandpass ${Sigma}-{Delta}$(Sigma-Delta) modulator used in wireless system receiver occurs a signal attenuation according to tuning of center frequency in signal bandwidth. In this paper, tunable bandpass 4th order SC bandpass ${Sigma}-{Delta}$ modulator with novel structure is proposed for rejection of signal attenuation in signal bandwidth. The existing structure uses a ten variable coefficient values for rejection of signal reduction in the modulator. But the proposed structure only use a two variable coefficient values for rejection of signal attenuation in the modulator. Also, an adder and comparator is replaced with a comparator having 4 inputs in the modulator. Therefore, the existing structure has one more OP-AMP. The purposed modulator was designed in $0.18;{mu}m$ CMOS technology. The resolution of the modulator within 310 kHz bandwidth and 40 MHz sampling frequency under 6.67 MHz, 10 MHz and 13.33 MHz intermediate frequency are over 10 bit.