Bi-functional Metasurface Polarizer for Reflected and Transmitted Waves

Manipulating the polarizations of electromagnetic waves by flexible and diverse means is desirable for a myriad of microwave systems. More recently, metasurfaces offer the promising alternatives to conventional polarization manipulating components because of the flexibility of their geometry could be arbitrarily customized. In this context, a bi-layered metasurface was presented to simultaneously manipulate the polarized states of reflected and transmitted microwaves. No matter whether the incident electromagnetic wave is x-polarized or y-polarized, the reflected and transmitted waves will be converted into orthogonal y- polarized waves at the operating frequency. The designed metasurface has a high polarization conversion rate(PCR) above 90% for both normal and oblique incidence. The experimental results verify the correctness of the simulated results. Finally, axial ratio and surface current distributions were employed to reveal the physics of polarization manipulation. The proposed metasurface will be beneficial to the design of flexible and versatile polarization converters and has great potential for applications in polarization controlled devices and also is believed extendable to higher frequency regimes.

Comparative Analysis of Compact Satellite Polarizers Based on a Guide with Diaphragms

In this article we carry out the comparative analysis of new compact satellite polarisers based on a square guide with diaphragms. The main electromagnetic parameters of the developed microwave guide devices with various amount of diaphragms were obtained within the satellite frequency interval from 10.7 GHz to 12.75 GHz. Waveguide polarization converters with different amount of diaphragms from 3 to 5 have been designed and optimized. The main parameters of the presented polarizer were calculated applying the numerical method of finite integration in the frequency domain. Optimization of the electromagnetic parameters of the developed waveguide devices was carried out using the finite elements method in the frequency domain. As a result, sizes of the guide polarizer designs have been optimized for the provision of improved polarization and phase parameters. The performed analysis showed that a waveguide polarizer with five diaphragms has the best electromagnetic parameters. The developed compact polarizer with five diaphragms based on a square guide provides a minimum deviation of the output phase difference from 90 degrees and high level of isolation between linear polarization over the entire operating frequency range. Presented in the article compact waveguide polarization converters can be applied in modern satellite systems, which require efficient polarization transformation and separation of signals.

Comparative Analysis of Compact Satellite Polarizers Based on a Guide with Diaphragms

In this article we carry out the comparative analysis of new compact satellite polarisers based on a square guide with diaphragms. The main electromagnetic parameters of the developed microwave guide devices with various amount of diaphragms were obtained within the satellite frequency interval from 10.7 GHz to 12.75 GHz. Waveguide polarization converters with different amount of diaphragms from 2 to 5 have been designed and optimized. The main parameters of the presented polarizer were calculated applying the numerical method of finite integration in the frequency domain. Optimization of the electromagnetic parameters of the developed waveguide devices was carried out using the software CST Microwave Studio. As a result, sizes of the device designs have been optimized for the provision of improved polarization and phase parameters. The performed analysis showed that a waveguide polarizer with five diaphragms has the best electromagnetic parameters. The developed compact polarizer with five diaphragms based on a square guide provides a minimum deviation of the output phase difference from 90 degrees and high level of isolation between linear polarization over the entire operating frequency range. Presented in the article compact waveguide polarization converters can be applied in satellite systems, which require efficient polarization separation of signals.

Bifunctional Metamaterials Using Spatial Phase Gradient Architectures: Generalized Reflection and Refraction Considerations

We report the possibility of achieving normal-incidence transmission at non-normal incidence angles using thin interfaces made of metasurface structures with an appropriately-designed positive spatial phase distributions. The reported effect represents a consequence of generalized reflection and refraction, which, although having been studied for discovering exotic effects such as negative refraction, to the best of our knowledge fails to address normal incidence conditions in positive phase distribution and its underlying consequences. Normal-incidence conditions can be angle-tuned by modifying the vales of the phase distribution gradients. Furthermore, for configurations around the normal-incidence angles, the metasurface will exhibit a bifunctional behavior—either divergent or convergent. All these properties are essential for applications such as optical guiding in integrated optics, wave front sensing devices, polarization controllers, wave front-to-polarization converters, holographic sensors, and spatially-resolved polarization measurement.

Band-Pass Filtering Cross-Polarization Converter Using Transmitarrays

Microwave devices with polarization conversion and band-pass filtering response have great application prospects on radomes. Here, the concepts of band-pass filters and cross-polarization converters are combined to realize a band-pass filtering cross-polarization converter with an extremely high polarization-conversion ratio. Most importantly, the device has an excellent out-of-band rejection level, above 30 and 40 dB for the lower and upper edges, respectively. In addition, the transmission zeros of the passband can be flexibly tuned independently. The band-pass filtering polarization converter was simulated, fabricated, and measured, and the measured results were found to be in good agreement with the simulation results.

Tunable broadband polarization converters based on coded graphene metasurfaces

In this paper, two optimization algorithms (randomly initialized hill climbing and genetic algorithms) are considered to design broadband polarization converters based on coded metasurfaces. A pixeled graphene patch with an elliptic structure is proposed for the initial solution. Each pixel can be 1 and 0 which represents the presence and absence of the graphene. The initial guess tends to the optimum configuration after several optimization processes. Four broadband polarization converters are designed utilizing the optimization algorithms. By changing the chemical potential of graphene, the operation frequency of the polarization converters can be adjusted. Furthermore, the effects of relaxation time of graphene and incident angle on the polarization conversion bandwidth of the four designed structures are investigated.