Broadband Reflectarray With High Polarization Purity for 4K and 8K UHDTV DVB-S2

Circularly polarized light plays a key role in many applications, including spectroscopy, microscopy, and control of atomic systems. Particularly in the latter, high polarization purity is often required. Integrated technologies for atomic control are progressing rapidly, but while integrated photonics can generate fields with pure linear polarization, integrated generation of highly pure circular polarization states has not been addressed. Here, we show that waveguide microring resonators, perturbed with azimuthal gratings and thereby emitting beams carrying optical orbital angular momentum, can generate radiated fields of high circular polarization purity. We achieve this in a passive device by taking advantage of symmetries of the structure and radiated modes, and directly utilizing both transverse and longitudinal field components of the guided modes. On the axis of emission and at the maximum intensity, we measure an average polarization impurity of 1.0×10−3 in relative intensity across the resonance FWHM and observe impurities below 10−4 in this range. This constitutes a significant improvement over the ∼10−2 impurity demonstrated in previous works on integrated devices. Photonic structures that allow high circular polarization purity may assist in realizing high-fidelity control and measurement in atomic quantum systems.

A 12-GHz (11.7 to 12.75 GHz) band satellite service with dual-circular polarization is studied for transmission channels to deliver advanced broadcasting services such as 8K (Super Hi-Vision) in Japan. A right- and left-hand circularly polarized parabolic reflector antenna will make it possible to receive the services provided over the dual-circular polarization with a single reflector antenna. An offset parabolic reflector antenna is generally used for satellite broadcasting reception, but its geometry creates deviations of the circularly polarized pattern peaks, resulting in pointing losses when applying it to a dual-circularly polarized antenna. To achieve sufficient gain for both polarizations, we studied reflector parameters and designed a dual-polarization offset reflector antenna. Simulation results showed that the antenna gain was more than 34.1 dBi for both polarizations and that the radiation patterns complied with the reference pattern in Recommendation ITU-R BO.1213.

This paper shows a millimeter wave (MMW) antenna based on low temperature co-fired ceramic (LTCC) technology with high polarization purity. By using the LTCC technology with multilayer parasitic patches in vertical direction, a wide bandwidth and high polarization purity can be obtained for the designed antenna. The V type patch is designed based on LTCC multi-layer technology, which is shaped by changing the distance of patch between different layers. By building this multi-layer structure, the polarization purity and bandwidth of antenna can be improved significantly. The simulation results show that the reflection coefficient of the antenna is smaller than −10 dB from 24.28 GHz to 27.84 GHz with a relative bandwidth of about 13.6%, and the cross-polarization isolation is higher than 50 dB within the operation band. The simulated results verify that the proposed antenna can be a promising candidate for 5G communication systems.

A novel variation of the conventional printed dipole antenna in combination with a modified microstrip via-free balun structure is proposed and named as the radiating integrated device (RID). By properly choosing their parameters, it is possible to create versions of the antenna that have suitable range of input voltage standing-wave ratio (VSWR) performance and radiation patterns. Prototype of this RID has been successfully implemented on a FAF-4 Russian printed-circuit-board substrate. Measured results of the 2.53 GHz RID have been compared with simulations and found to be in good agreement. The proposed antenna with the via-free balun, relatively low profile, and high polarization purity is very suitable candidate for mobile communication systems with single linear, dual linear or circular polarization.

Layered Division Multiplexing (LDM) has demonstrated increased data rate capacity for wireless applications where the service bitrates being multiplexed are unbalanced. Current Direct-To-Home (DTH) broadcasting satellite standards (DVB-S2 and DVB-S2X) include Variable Coding and Modulation (VCM) mode. VCM provides the opportunity to deliver different services on a Time Division Multiplexing (TDM) basis and in consequence target different reception conditions with a single carrier. This article proposes the combination of the tools provided by DVB-S2X with LDM for satellite broadcast and communication systems. This article describes use cases where multiplexing schemes can be beneficial in comparison with VCM (TDM) approach. The use cases include the delivery of High Definition (HD) and Ultra High Definition (UHD) TV services to customers as well as additional communication services. The performance of the proposal is evaluated with simulations under different channels, including the impact of satellite equipment non-linearities. Analysis shows that LDM provides considerable gain in comparison with VCM in both AWGN and non-linear satellite channels.

In 1934 two English investigators (1) published a method for calculating the various modes and frequencies of vibration of a system having several degrees of freedom. Their method, which is based on matrices, greatly shortens the time spent in obtaining numerical solutions in many important problems, notably those with immovable foundations. In this paper is presented a new theorem which (a) makes possible a further reduction of nearly one half in the time required, so that solutions up to 20 deg or more of freedom are now practical and (b) makes it then possible to determine the motion of the system after any initial disturbance in a few minutes, instead of several hours as required by older methods. It is useful in the latter respect whether the modes have been determined by matrix methods, or not. Although the paper gives simpler proofs than any previously published, knowledge of the matrix theory is not required in using the method. Problems are analyzed by a tabular process, in which an ordinary computing machine helps greatly. Comments based on computing experience are given. A simple numerical example has been given elsewhere (1).

As the number of resonances increases, it becomes difficult to improve and maintain the performance of dielectric resonator antennas (DRAs), over the expanded impedance bandwidth. To remove unwanted modes, adjust the frequency distance between individual modes, reduce antenna size and cross polarization, and preserve radiation patterns in a wideband configuration, a dielectric resonator antenna fed with parallel standing strips is proposed in this paper. The use of parallel standing strips provides several degrees of freedom in the design procedure to enhance the DRA characteristics. To validate the effectiveness of this approach, two DRAs with parallel standing strips were fabricated using different procedures. The antennas were tested and characterized. The measured results are in good agreement with simulation ones. A 46% size reduction was achieved for the multimode DRA. The impedance bandwidth of the proposed DRA of simple rectangular shape was over 60% with a measured gain ranging from 5.5 to 9.5 dBi. Broadside radiation patterns with fairly low cross polarizations can be maintained over the impedance bandwidth. The simulated radiation efficiency is more than 96% within the frequency band.

In this paper, the design, simulation and measurement results of a 2×2 circularly polarized microstrip antenna sub-array at Ka-band are presented. The proposed antenna sub-array employs the sequential rotation technique for improvement of AR bandwidth with high circular polarization purity without degrading the circularly polarized gain. The 3-dB gain reduction due to using sequential rotation technique is compensated by employing an antenna element with wide axial ratio bandwidth. The antenna array has a wide impedance bandwidth (S11< -10 dB) of 6.5 GHz from 26-32.5 GHz. The antenna has a wide axial ratio bandwidth (AR< 3 dB) of 6.2 GHz from 25.4-31.6 GHz with high circular polarization purity. The 3-dB gain bandwidth of the antenna is from 25.5-31.2 GHz and the peak gain is 12.1 dBic. The antenna is fabricated through multilayer printed circuit board process and has a size of 18.5 mm × 18.5 mm × 1.02 mm.

This paper presents the design, simulation, and experimental validation of a dual-Circularly Polarized (CP) array antenna to be used as single element for a bistatic radar system, aimed at detecting and tracking objects in Low Earth Orbit (LEO). The antenna operates at 412 MHz in reception mode and consists of an array of 19 slotted-patch radiating elements with a cavity-based metallic superstrate, designed to support dual circular polarization. These elements are arranged in a hexagonal configuration, enabling the array structure to achieve a maximum realized gain of 17 dBi and a Side Lobe Level (SLL) below −17 dB while maintaining high polarization purity. Two identical analog feeding networks enable the precise control of phase and amplitude, allowing the independent reception of Right-Hand and Left-Hand Circularly Polarized (RHCP and LHCP) signals. Full-wave simulations and experimental measurements confirm the high performance and robustness of the system, demonstrating its suitability for integration into large-scale Space Situational Awareness (SSA) sensor networks.

The Slepian model process method has turned out to be a powerful tool to obtain accurate approximations to the long run probability distributions of the plastic displacements of a one degree of freedom linear elastic-ideal plastic oscillator (EPO) subject to stationary Gaussian white noise excitation. The paper extends the method to the simplest EPO of more than one degree of freedom. This EPO contains only a single structural component that can yield. It is experienced by direct response simulation that the loss of the property of slowly varying amplitudes when extending to more that one degree of freedom tends to jeopardize the assumption that the position of the response amplitude at the end of any clump of plastic displacements has practically no influence on the distributional properties of the response just before the start of the next clump of plastic displacements. Therefore the results obtained herein strictly apply to the first clump and not to any clump of plastic displacements. Under this restriction the obtained Slepian model results fit well with the results obtained by direct response simulations. Also it is observed that the restriction gets less importance for decreasing intensity of the white noise excitation.

An S-band dual circular polarizer has been designed and tested with low power in the paper, which will be applied in a spherical cavity pulse compressor. It converts the TE $$_{10}$$ mode in rectangular waveguide into two polarization degenerated TE $$_{11}$$ modes in cylindrical waveguide. The general scattering matrix of the dual circular polarizer has been deduced based on the properties of the passive microwave network, which is suitable for the usual 3 dB coupler, as well as the left/right hand circular polarizer. Based on the 3D code software CST, the dual circular polarizer was numerically simulated. Then, two prototypes have been manufactured and tested with the vector network analyzer (VNA). The simulation results show that the magnitudes and phase difference of the two TE $$_{11}$$ modes are − 3.0103/− 3.0104 dB and 89.79 degrees, respectively. The cold test results show good agreement with CST simulation. The method of analyzing the relationship between the voltage standing wave ratio (VSWR) and the errors of the magnitudes and phase difference of the two TE $$_{11}$$ modes was given, which can be used to qualitatively analyze the properties of the circular polarizer. The S-band waveguide dual circular polarizer can be applied in the pulse compressor, phase shifter or other frequency bands.

In this paper, a novel broadband circularly polarized reflectarray covering the entire Ka-band is proposed. An S-shaped patch structure is embedded at the center of the electric dipole to achieve circularly polarized reflection functionality. Based on the element rotation method, phase modulation for incident circularly polarized waves can be achieved. The simulated results show a 3-dB gain bandwidth and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$1.5-\text{dB}$</tex> axial ratio bandwidth of 42.4% and 42.4%, respectively. The peak aperture efficiency of 58.2% is obtained. The operating bandwidth of the reflectarray covers the entire <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$K a$</tex>-band, demonstrating excellent broadband performance. The proposed reflectarray finds versatile applications across various fields, including satellite communication networks and advanced radar systems.

Circularly Polarized Monopulse Antenna Array with Low Sidelobe Level and High Polarization Purity

Planar antenna arrays of a balanced structure are of great importance in many applications due to their features including low‐profile, wideband, and high polarisation purity. However, feeding such antennas adds great complexity in terms of manufacturing and reduces the performance due to production of common mode propagation. A method for feeding such antennas using coplanar waveguide on a thin substrate is proposed. Not only does it terminate the antenna of a balanced structure with a single‐ended feed but it also enables impedance transformation. The design was an attempt towards a completely printed front‐end that incorporates the antenna elements and their feeding circuits on bendable substrates. The electromagnetic performance has been validated with a dual polarised prototype and its prospect for ultrawideband arrays, e.g. 5G sub‐6 GHz or square kilometre array, was explored.

An electrically small array antenna (ESAA) is proposed including two tightly coupled half-monopole antennas (TCMAs) as a single radiation element with two excitation ports. By properly using two consecutive inductive-capacitive loadings in the conventional bi-element monopole, total electrical length of the resonant frequency is increased, significantly and then the frequency migrates from 4 to 0.5 GHz as a frequency sample (i.e., an 88% reduction). This combination consists of several stubs on each of the monopoles and an interdigital capacitor designed in the dead space between them so that only a compact overall size of 0.02 λ 0 × 0.035 λ 0 at 0.5 GHz is occupied. The studies on different subsections of the TCMA are done and additionally an extended circuit model and simplified one are presented which agrees well with simulation. Due to the fully symmetrical design and elimination of the cross currents, a stable omni-directional radiation pattern with high polarization purity and radiation efficiency over 20 dB and 78% is achieved, respectively. An implemented prototype exhibits an improved impedance matching and measured 10 dB S11 bandwidth of 34% which are in good agreement with simulation. The proposed TCMA can be a good candidate for compact wireless systems such as RFID sensors.