Hiding a detector is not a nascent topic yet, which has many fascinating and important applications in both civil and military areas. In antenna fields, microwave engineers often use an absorbing or frequency-selective layer to construct a radome in order to reduce the radar-echo of inner antenna. However, the absorbed or redirected incident wave is out of the operating band of the antenna, thus having no consequential help on the reduction of antenna’s in-band echo. As a result, it is a challenge to reduce the antenna’s in-band echo, which has attracted much attention during the last 50 years. In this paper, we designed and demonstrated a low-echo metamaterial (MM) shelter with in-band electromagnetic narrow window. The unit-cell of the MM shelter is composed of two basic elements: a metallic square-loop with two small gaps in each side, and an electric-resonant-ring (ERR) embedded into a sub-wavelength aperture. Eight chip-resistors are respectively inserted into the gaps of square-loop to provide necessary lossy source. When the electromagnetic wave impinges the square-loop side, most of the energy would be absorbed by these chip-resistors, provided that the oscillating frequency does not coincide with the resonant frequencies of the ERR. At the resonant frequency of the ERR, the interplay of the transmission and absorption may greatly increase the transmitted energy through the aperture decorated with ERR. By introducing a selective re-emission mechanism of the energy captured by an absorbing layer, we observe that at least half of energy can pass through the narrow window located into the absorption band, and the broad low-echo feature is not influenced. The performance of the MM shelter and its ability for shading electromagnetic receiver is demonstrated by carrying out a numerical experiment, including three main portions: a dipole array acting as a signal receiver, a remote point source with tunable amplitude utilized to model the far-field excitation of a signal source, and an inserted MM shelter. This device is believed to be suitable for the in-band scattering reduction of antenna which is especially designed to work in the receiving mode. We expect that, the concept and design reported here will influence the future design of electromagnetic absorber and radome, generating a new research hot topic in electromagnetic invisibility field. Our design may be applied in wireless local area network to cancel additional multi-paths, or signal degradation because it can effectively absorb useless signals without significantly attenuating mobile phone signals.