Self-Casing Low-Cost Reflectarray With a Single Porous Layer

A self-casing Microstrip Reflectarray Antenna (MRA) is proposed with high-gain, broadband, mechanically simple properties. It needs no radome due to exploiting a low-cost porous superstrate. Such an inhomogeneous layer is made up of the robust FR4 dielectric in which air rods are periodically drilled. This porous layer is suspended above the metallic plane using spacer and the re-radiating elements are printed on its interior side for designing a broadband center-fed MRA. Its element is a new Butterfly-Like Patch (BLP) with two degrees of freedom (length and angle). By analyzing its sub-wavelength unit cell, the calculated total phase range is more than 700°, which can be a good choice for broadband MRA design. Using this phase response and an efficient phase synthesis technique, an optimized metallization arrangement is analytically obtained to design a good frequency behavior MRA. To validate the numerical results, a
$270\times 270\times 3.9$
mm3 MRA with focal length 26.1 cm is manufactured and tested. Measured results show a peak gain 29.1dB with a 1-dB gain bandwidth of 42.6% (
$9.7\sim 14.9$
GHz) and maximum efficiency 58% at central frequency 12GHz. It is experimentally shown that the gain and bandwidth of this self-covering MRA is better than conventional one.