We propose a $2\times2$ patch array filtenna specifically designed for radio altimeter applications with significant suppression of unwanted adjacent 5G spectrum signals. The patch radiator is carefully selected to meet the radiation requirement of radio altimeters and the substrate integrated waveguide (SIW) feeding network is meticulously designed to provide shielding property and e... https://chefesquipmenters.shop/product-category/deep-fryer-filter-paper/