5G cellular applications operating at 28 GHz millimeter wave (mmW) frequency demand compact yet high gain antenna system implementation to meet the service requirements. In this chapter, a modified antipodal Vivaldi antenna (AVA) topology has been discussed that features elliptical-shaped corrugations and a metal director in the design. This modification has resulted in a compact planar antenna with dimensions of 20 mm × 7.4 mm, a peak gain of 8.82 dB, and an impedance bandwidth of 35%. To further improve the gain, the proposed antenna has been used in designing a 1 × 4 linear antenna array (AA) by implementing a full corporate feeding structure. With dimensions of 35.3 mm × 36.6 mm, this AA has a peak gain of 13.67 dB and a beamwidth of 14°. To improve spatial coverage, a compact single-layered multibeam antenna (MBA) using the proposed 1 × 4 AA and a 4 × 4 Butler matrix-based planar beamformer has been implemented. With a form factor of just 58.6 mm × 37.7 mm, this MBA can produce four spatially distributed beams, each with a beamwidth of 15.1°, to achieve a wide coverage over a frequency range of 26.5–30.5 GHz. These antennas are suitable for mmW 5G applications.