A novel dual-band patch antenna with low-profile, enhanced bandwidth, and half-power beamwidth (HPBW) is designed. Firstly, the radiation pattern of the antenna is investigated by using the cavity model. The results prove that its E-plane HPBW in dual frequency bands could be improved by alternatively using a single equivalent slot. After that, an array of four slots is cut around nodal lines of its electric fields at higher radiative mode, aiming to reallocate the upper frequency band. Lastly, the designed MPA is simulated and fabricated. The measured results illustrate that it has successfully acquired an extended-bandwidth (|S|<-10 dB) in dual bands of 2.54-2.8 GHz and 4.28-4.4 GHz with two attenuation poles, while keeping a low-profile property. Besides, the HPBW of the patch antenna at E-plane is dramatically pushed up to about 135° during dual separated working bands.