Enhancement of boresight radiation for leaky wave antenna array

The variation of substrate material with the reflection coefficient that shows in Figure 3 The dielectric constant steady at higher frequency laminates of Rogers RT5880 is the lowest of all items of substrates, and low dielectric misfortune influences them to appropriate for high frequency/wide band applications where scattering and misfortunes should be limited. A characteristic feature of these antennas is that the electromagnetically field is exciting by a wave which is incident on the interior or on the exterior of the guiding structure which produces currents that propagate along its longitudinal direction. leaky wave modes propagation energy along the longitudinal bearing in the dielectric substrate, with just the misfortunes and to be identified with the materials. the radiation pattern when used FR4 substrate is very small value and have two beam width because the mismatching between patch leaky wave antenna and FR-4 substrate. Figure 8 show that the reflection coefficient (S11) with gap S, and chose three values of S, S1 and S2, S1 = 2.1 mm when remove the first via and S2 = 3.1 mm when remove 2 vias an appropriate S is required between the end of the feed line and the center of first via to force the wave toward the microstrip edges, as well as to improve impedance matching at S = 0.6 mm. 4.Results & Discussion Figure 9 shows the scattering parameters ⅛ of the array. Since the array is fed its center each element of LWAs, the two beams of two elements combine to produce one beam toward the boresight direction.