ABSTRACT
In modern sensor and communication systems, there is an increasing demand for the monolithic
integration of the antennas with the RF front-ends to avoid external transmission line connections or
sophisticated packaging, thus reducing manufacturing cost and improving system performances [1, 2].
Especially, microstrip antennas are used in a broad range of applications from communication systems
(WLAN, radars, telemetry, and navigation) to biomedical systems, primarily due to their simplicity,
conformability, and low manufacturing cost. They are commonly utilized in wireless applications due to
the fact that can be planar or conformal, can be fed in numerous configurations and also are compact
and suitable for antenna array designs. In general, they can be used in applications requiring high-
performance compact low-cost planar antennas. With the recent development of microwave-and
millimeter-wave integrated circuits and the trend to incorporate all microwave devices on a single
chip for low-cost and high density, there is a need to fabricate microstrip antennas in a monolithic
fashion with the rest of the circuitry on semiconducting materials such as silicon, GaAs, or InP. One of
the main limitations of these microstrip antennas is the excitation of surface waves in the silicon
substrate, especially in cases where the bandwidth and the radiation efficiency requirements demand
large values of the substrate thickness, resulting in compromised efficiency, reduced bandwidth, and
degradation of the radiation pattern [4, 5]. Furthermore, in monolithic designs the feedlines share in
most cases the same interface with the antennas and lead into parasitic radiation, which deforms the
antennas’ pattern and increases crosstalk.
