A Low Frequency Compensated TEM (LFCTEM) horn antenna realizes a poor gain in the lower part of operating bandwidth. This paper presents the Modified LFCTEM (MLFCTEM) antenna which has elliptical cutting shapes on LFCTEM to improve performance at the low frequency. To verify the improvement of the proposed antenna performance, MLFCTEM is compared with the LFCTEM antenna. Simulated results show that the MLFCTEM has return loss less than -10 dB in the frequencies from 2 to 18 GHz. In the case of being compared to the LFCTEM, it also has had an improved gain value at the low frequency which increases up to about 2.5 dB and has more directive radiation pattern.