A new type of detector array is described. By means of a suitably designed metallic network, many detector elements (each individually small compared to wavelength) are assembled into an impedance-matched termination for radiation incident normally on the plane of the device. Residual reactance is tuned out by means of a movable backshort. An array of 400 bismuth-film microbolometers with a total area of 1 cm2has been tested at 215 GHz. A coupling efficiency of approximately 60 percent was observed. The detector has a of cm . Hz1/2/W at room temperature with response time on the order of s. Similar arrays of Schottky and SIS diodes can probably be constructed.