Abstract: Radio pulse propagated through the ionosphere is distorted by the ionospheric dispersion effect and the radar performance for probing is seriously degraded. We investigate the ionospheric phase and polarization dispersion effect on linear polarization radar signal in this paper. The convolution envelope between the transmitted and the received signal is derived. Then we make analysis and calculation about the pulse duration and range resolution under different frequency and relative bandwidth. The results show that the dispersion effect becomes more serious when relative bandwidth increase or the signal frequency decrease. The polarization dispersion is very weak when the carrier frequency is more than 600 MHz.The polarization dispersion is notable and stronger than the used phase dispersion when the carrier frequency is about 100 MHz. The phase dispersion is always notable even to the carrier frequency between 100 MHz and 30 GHz.