a randomized elliptical grid disposed on a sensor window for electro - magnetic and / or radio - frequency shielding of sensors , and a method of applying same . grids may be made of electrically conductive or resistive material and may include elliptical or circular shapes . the shapes are in physical contact with each - other and preferably do not contain straight lines to reduce detection artifacts caused by the coating . grid element shape , size , orientation , and grid pattern density may be randomized or varied across a sensor window .