MeMiTec/8GHz Patch antenna
An edge-fed rectangular patch microstrip antenna was design on a very low cost FR-4 substrate. The design was first carried out using Momentum and then implemented on the substrate using a Rapid PCB Prototyping system. The antenna was then characterized in terms of reflection coefficient using a network analyzer obtaining a fairly good agreement between simulations and experimental data.
In particular, the fabricated antenna is centered at a frequency 100MHz higher than the simulation. The percentual error between measurement and simulation is therefore around of 1%, which has to be regarded as a good result. The agreement was achieved by setting the electrical permittivity of the substrate to a value of 4.25 instead of 4.7, as claimed by the substrate constructor. This result stems out from the fact that the FR-4 is usually employed for applications at frequencies lower than 9GHz. The radiation pattern of the antenna was then simulated again using Momentum, that provided also the main antenna characteristics, as the gain, that was about 6dB and the directivity, that was around 8dB.
The good agreement between the Momentum simulations and the experimental data demonstrate that X-band passive structures can be fabricated using very low cost substrate as the FR-4 even if the right value of the electrical permittivity should be determined