An atom-based approach is presented to detect absolute microwave (MW) electric fields (E-fields). The approach uses Rydberg atoms in vapor cells at room temperature. The MW E-field measurements utilize a bright resonance prepared within an electromagnetically induced transparency (EIT) window. The large transition dipole moments between energetically adjacent Rydberg states enable this method to make traceable E-field measurements with a sensitivity that is several orders of magnitude higher than the current standard for MW E-field measurements. The method can be used to image MW E-field in the near field regime with a subwavelength resolution of λMW/650, where λMW is the wavelength of the MW E-field. A high accuracy of 1% has been reached by minimizing the effects of the vapor cell geometry on the measured MW E-field. The dissertation also presents an alternative technique to perform the MW E-field measurement using dispersive properties of the EIT spectrum with a prism vapor cell. Recently, we applied a homodyne detection technique with a Mach Zehnder interferometer to achieve a new sensitivity limit for the MW E-field measurement, ∼3 μVcm−1Hz−1/2. The new sensitivity is one order of magnitude better than our prior best sensitivity presented in Ref. [Nat. Phys. 8, 819 (2012)]. The Rydberg atom-based method is promising to be a new standard for MW E-field measurements and to develop into portable devices in the field of MW technologies.