A >40% bandwidth fully scalable turnstile-based waveguide orthomode transducer having excellent phase performance is described for the WR75 standard rectangular waveguide. Flexible bandwidth tuning is achieved through the use of an interchangeable stepped scattering element. Reduced height waveguide topology provides a simple, compact, and robust design against mechanical tolerances. The intrinsic broadband nature of half-height E-plane bends and single-step power combiners assures high order mode free increased bandwidth in balanced phase operation. The designed orthomode transducer exhibits a return loss better than 23 dB at any port, an insertion loss less than 0.06 dB, and an isolation of 50 dB over the full bandwidth. Moreover, the phase difference between orthogonal polarizations is lower than 0.7° over the band, thus enabling applications where phase-matched outputs are required. This design has been chosen for the QUIJOTE cosmic microwave background experiment due to its cost-effective, compact design, and high-quality performance as well as being readily scalable to the WR51 and WR28 waveguide bands. © 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2010.

The Microwave Power Transmission (MPT) is the possibility of feeding a system without contact by using microwave energy. The challenge of such system is to increase the efficiency of transmitted energy from the emitter to the load. This can be achieved by rectifying the microwave energy using a rectenna system composed of an antenna of a significant gain associated with a rectifier with a good input impedance matching. In this paper, a new multiband antenna using the microstrip technology and fractal geometry is developed. The fractal antenna is validated into simulation and measurement in the ISM (industrial, scientific, and medical) band at 2.45 GHz and 5.8 GHz and it presents a wide aperture angle with an acceptable gain for both bands. The final antenna is printed over an FR4 substrate with a dimension of 60 × 30 mm². These characteristics make the antenna suitable for a multiband rectenna circuit use.

This paper presents a novel low-cost integrated multiband antenna design customized for smartwatch applications and wearable devices. The design consists in using a broadband planar patch antenna with circular microstrip lines and a miniaturized feeding-point with a structure of 30×30×1.6mm³, and it is easy to deploy inside the smartwatch and cost-effective for the wearable device industry. The parametric study and final dimensions of the design and the measured results of the reflection and radiation pattern are discussed. The antenna with maximum gain up to 6.6dBi and S₁₁ up to 22dB exhibits excellent performance for all the frequencies required in wearable systems such as 1.9GHz, 2.3GHz, 2.4GHz, 2.6GHz, 5.2 GHz, and 5.8GHz. We drew a comparison between similar research and this work in terms of antenna performance. Furthermore, we investigate the specific absorption rate (SAR) performance of the antenna for the smartwatch application, using both human hand wrist multilayer and SAM head mouth models. The SAR results in different positions for all the frequencies are compared to the Federal Communication Commission (FCC) standards.

Differential phase shifters are common circuits in communication systems where a fixed phase difference between two points within the circuit is required. Among the available technologies, waveguide phase shifters are preferred for applications such as antenna feed or beam-forming networks. Typical designs in the literature are devoted to specific phase delays such as 90° or 180°, but any phase shift might be required, and therefore a design procedure resulting in mechanically-related parameter fitting equations for any arbitrary phase difference would be advantageous. This paper presents a parametric design of full-band (40% relative bandwidth) waveguide differential phase shifters, providing polynomial equations for all design parameters in order to obtain arbitrary phase shifts between standard rectangular waveguides with equal physical lengths. The phase shift is achieved through the use of a multi-step ridge section together with a single width-step in the shift line. The proposed design procedure results in differential phase shifters with 25 dB of return loss and minimal physical length for any phase shift between 0° and 180°. To validate this parametric design process, two exemplary differential phase shifters with 30° and 140° phase shifts were measured, showing very good agreement with the simulated results.

This paper presents a compact 2 × 2 multiple-input multiple-output antenna system designed for 5G smartphones operating in the upper 6 GHz band, and which is to be initially considered as a prototype resembling a user terminal in a channel sounding system. The antenna incorporates a split-ring resonator metamaterial layer, enhancing its gain by at least 1.5 dB across the entire bandwidth without increasing the size of the antenna. The results show a good agreement between the simulations and measurements, achieving a strong isolation, below −18 dB; a low envelope correlation coefficient, lower than 0.025; as well as an efficiency exceeding 75%, making it highly suitable for 5G wireless applications, including both indoor as well as outdoor wireless channel characterization.