In this paper, a millimeter-wave printed quadrupole antenna is proposed. It consists of two symmetric printed dipoles that make the quadrupole radiating power omnidirectionally. Such an arrangement eliminates the influence of the ground as reflector. Simulation results show that the quadrupole antenna exhibits a broad impedance bandwidth and an enhanced gain compared to conventional dipoles. More interestingly, the configuration of the quadrupole includes an integrated feed network, making the design compact. Next, a novel omnidirectional array was designed, simulated, fabricated, and measured, exhibiting enhanced features like compactness, broad bandwidth, high gain, high efficiency, low cross-polarization, low cross-polarization level, low cost, and low profile.