The Moment Method is used to estimate the error induced by a compact measuring probe in the near-fleld. A crossed-dipole is used as a compact near-fleld measuring probe of a waveguide radiator in an inflnite ground plane, since it measures both co-pole and cross- pole components simultaneously. However, due to multiple re∞ections between radiator and probe, in addition, mutual coupling efiects between the poles, near-fleld values are changed. The relative sampled electric fleld pattern (without the probe) is compared to the relative sampled co-pole voltage pattern in the scan plane and the induced error is computed. The radiating waveguide's re∞ection coe-cient is altered with respect to the re∞ection coe-cient when there is no probe in the near-fleld. The numerical results concerning the re∞ection coe-cient without the probe are compared to the measured values, and good agreement is observed.