In this letter, a low-cost dual-polarized broadband dipole antenna is studied for RF energy harvesting applications. The 2×2 antennas are arranged with a rotational symmetry over an Artificial Magnetic Conductor (AMC) surface to capture the ambient RF energy from both the Horizontal (H) and Vertical (V) polarizations in a multiple input multiple output (MIMO) environment. The antenna is then integrated with a single-series rectifier circuit network in a series fashion. In the final step, an LED is connected as the common load to demonstrate the process of capturing the RF energy, thereby glowing the LED.

Recently, it has been a feasible approach to build an antenna, in view of the potential advantages they offer. One of the recent trends in dielectric resonator antenna research is the use of compound and hybrid structures. Several considerable investigations have been already underway showing quite interesting and significant features in bandwidth, gain, and generation of circular polarization. A critical review on a journey of circularly polarized hybrid dielectric resonator antennas is presented in this article. A general discussion of circular polarization and DR antennas are provided at the forefront. Evolution, significant challenges, and future aspects with new ideas in designing hybrid dielectric resonator antennas are indicated at the end of the review. State-of-the-art advances and associated design challenges of circularly polarized hybrid DR antennas and related empirical formulas used to find resonance frequency of different hybrid modes produced are discussed in this paper.

A log‐periodic dielectric resonator antenna for possible wideband operation is considered. The proposed design consists of seven dielectric resonators (DRs) of rectangular cross‐sections using a low‐cost Teflon‐based dielectric material with low permittivity. It has a multilayer configuration, where the DRs and feeding line are located at different layers. For ease of fabrication, the radiators are excited by an overlaid microstrip feed line on the first layer. Different characteristics such as S ‐parameters, gain, input impedance and radiation patterns of the proposed design are studied. The fabricated prototype exhibits a gain of 6 dBi (or better) over a wideband of 6.5–11.3 GHz with | S ₁₁ | less than − 10 dB. The results from the simulation are found to closely follow those of the fabricated prototype.

High power microwave (HPM) systems using vacuum electron devices as source with TM01 circular waveguide output mode, often require a TM01 to TE11 mode converter for ease of coupling to the radiating system. Some novel cylindrical waveguide TM01 to TE11 mode converters using single and multiple cells of step waveguide discontinuities (SWDs) are proposed. It offers the advantages of high conversion efficiency, high power-handling, moderate bandwidth, and compact size. To validate the concept, the 3-GHz circular waveguide TM01 to TE11 mode converters with single-, dual-, and triple-SWD cells of discontinuities have been designed and simulated using a 3-D electromagnetic solver. It is observed that the bandwidth and power-handling capability increase as the number of SWD section increases. The dual-SWD cell-based mode converter (DSC-MC) was experimentally tested at low power using a network analyzer and by measuring its radiation pattern through a horn antenna. This mode converter demonstrated a bandwidth of 6.93%, a conversion efficiency of 91%, and a computed power-handling capability of 848 MW in a compact size of $1.71\lambda _{{0}}$ .

A capacitive coupled Dielectric Resonator Antenna (DRA) array based on log periodic technique is investigated experimentally for X-band applications. The Frequency Independent DRA array consists of seven rectangular Dielectric Resonators (DRs). The DRA array has been excited by a series fed microstrip line. Since the resonators are directly coupled to the feed line, it results in more compact and lower loss DRA array. The proposed DRA array has been designed and realized. The measured results are in good agreement with the simulations. The designed array is operating over the frequency range 6.2–12.2 GHz for 2:1 VSWR with the fractional bandwidth 65.2%. The array provides a peak gain of 9.09 dBi with the broadside radiation pattern over the widespread operating band. The proposed design is useful for X-band applications.