Effect of adhesive bonds on electrical performance in multi-layer composite antenna

We study experimentally the effect of adhesive bonds in a multi-layer composite antenna. Changes in the antenna performance after the bonding process were determined. Three types of antennas were designed and fabricated, with different resonant frequencies. The measured electrical performances of these fabricated structures reveal that all antennas undergo a fall in their resonant frequencies and a reduction in the gain. The change in resonant frequency is related to a change in the effective dielectric constant of the assembly, and the gain falls due to loss in the adhesive. Corrections were then introduced in the design process so as to compensate for the effect of the adhesive. The measured results for the modified antenna show excellent agreement with the target performance.