Using surface microwaves for measuring and determining density and/or moisture content of a material. Positioning material within a proximate free space region spanning immediately above surface of a surface microwave waveguide, the surface microwave waveguide includes an electrically conducting rectangular block and a dielectric rectangular insert element compactly fitting into the block. Transmitting microwaves into the first end of the surface microwave waveguide, a first portion of the transmitted microwaves propagate within the surface microwave waveguide and a second portion propagates within the proximate free space region including the material. Parameters (amplitude, phase, attenuation, and phase shift) of the propagating microwaves are perturbed by the material and are a function of density and/or moisture content of the material. Receiving the portions of propagating microwaves exiting the surface microwave waveguide, whereby the parameters of the transmitted and received microwaves are useable for determining density and/or moisture content of the material.