In this paper, we propose a new varactor coupled line structure and design the VCO using the proposed structure. The proposed coupled line structure removes the reflected signals from the varactor diode using an added $lambda$/4 transmission line. The frequency synthesizers are designed using the PLL technique at Ku-band. The synthesizer using the proposed coupled structure has 38 MHz frequency tuning range and -97 dBc/Hz phase noise characteristic at 100 KHz offset frequency. The measured results show improved tuning range as well as the improved phase noise characteristics compared to the conventional designs.