Technologies for Near-Field Focused Microwave Antennas

Abstract

This paper provides a review spanning different technologies used to implement near-field focused antennas at the microwave frequency band up to a few tens of GHz: arrays of microstrip patches and printed dipoles, arrays of dielectric resonator antennas, reflectarrays, transmitarrays, Fresnel zone plate lenses, leaky-wave antennas, and waveguide arrays.

An Overview on Synthesis Techniques for Near-Field Focused Antennas

“…Almost any antenna technology can be used to realize NFF antennas, as it is just required to modify the layout of a conventional unfocused antenna to get the proper phase profile of the radiation currents on the array/aperture surface. An overview of the different technologies that have been applied to prototype NFF antennas can be found in [2]. Among them, it is worth mentioning reflectarrays and transmitarrays, linear and planar arrays (made of dipoles, patches, dielectric resonator antennas), planar slotted waveguide antennas, lens antennas, dielectrically loaded horn antennas, elliptical reflectors, substrate integrated waveguide (SIW) antennas, leaky wave antennas, and Fresnel Zone Plate Lens antennas.…”

Again on Spatial Focusing and Shaping of the Electromagnetic Field in the Antenna Radiative Near-Field Region

“…In 2017, an extended overview of the basic properties, achievable performance and design criteria for NFF antennas has been presented in [1], while a summary of the different technologies used to implement NFF antennas was made available only a few months later in [2]. Since then, a number of research groups presented novel layouts, effective synthesis techniques and valuable applications, for NFF antennas with operating frequencies from microwave frequencies up to tens of GHz.…”

“…Since then, a number of research groups presented novel layouts, effective synthesis techniques and valuable applications, for NFF antennas with operating frequencies from microwave frequencies up to tens of GHz. In this paper, the authors want to give an updated overview with respect the above mentioned review articles [1]- [2], for a better understanding of the actual research trend. Specifically, Sect.…”

Impact on focal parameters for near‐field‐focused aperture antennas

“…Near‐field‐focused (NFF) antennas have been becoming an interesting research field in some applications such as NF radiometry, medical imaging, and tissue hyperthermia . The basic idea is to control the phase of the radiation sources on the antenna's aperture so as to enhance the electromagnetic power density in a specific region near the antenna aperture . In addition, compared with the NFF antennas with tapered phase distributions of the radiation sources, far‐field‐focused antennas are with uniform phase distributions of the radiation sources.…”