An omnidirectional quad-loop antenna has four open circular wire loops, each being the same length as the wavelength of a Wi-Fi signal. The loops are joined at their tops and each lies in a distinct plane that is rotated 45 degrees with respect to each adjoining wire loop. The bottom terminal ends of the loops are configured to connect to the outer conductor of a coaxial cable. A helical wire coil may be connected at one end to the loops at the connection point, or insulated from the loops, and the other end is configured to connect to the inner conductor of the cable. With the antenna and cable connected to a router, the Wi-Fi signal is much stronger, in any direction, than without. The compact antenna fits within the volume of a sphere with a circumference corresponding to the wavelength.