This paper presents an element of a 2×2-element array antenna for Inmarsat BGAN/GPS applications. The element is an axial mode printed quadrifilar helical antenna that has been integrated with a compact feed network to provide sequential phase rotation for circular polarization (CP) radiation. The novel integrated lumped-element feed network is designed to provide a balanced RF power to the four helix arms with a 90° sequential phase difference between them. The design maintains a low cross polarization, and accordingly, a high quality of RHCP up to ± 66° over the transmit frequency band of 1616 MHz to 1626 MHz. The gain in this frequency range is higher than 3. 5 dB with a return loss better than 11 dB and a perfect circular polarization performance (axial ratio ~0 dB). The proposed antenna has small size, light weight, low cost, almost hemispherical radiation pattern and excellent circular polarization that can become a good candidate in satellite L1-band and BGAN satellite communications.

Two ultra-wideband small blade shape antenna are presented and compared. First structure is composed with a blade radiator with a lossy element on the feed point. The second structure has composed with a monopole with a mean derline load. This antenna has three lumped RLC elements that optimized for higher gain and return loss. The antenna is shaped like a very thin blade monopole and is constructed with an one-sided printed board. The dimension of both antennas is 22 × 76 cm (0.076 l × 0.022 l × 0.00015 l of lowest frequency) with a 25 x 50 cm ground plane. It is showed that the characteristics of second antenna are too better than first one, especially in lower frequencies. The advantage of second antenna is the higher gain and removing the gain notches in line of sight despite of small size and a good matching in 30 – 500 MHz frequency band.

In this article, an active electrically small Horn antenna for very high frequency (VHF) and ultra-high frequency (UHF) frequencies is presented. The proposed horn antenna has a height of 5 cm and a diameter of 4.28 cm which can cover 6-12 GHz without a special active circuit with the VSWR of less than 2. A Non-foster Active Adaptation Circuit is used to reduce the antenna input frequency from 164 MHz to 880 MHz. Good matching is visible between the simulation results and the measurement of the antenna reflection coefficient with the active matching circuit. The proposed structure has more than 137 % bandwidth. With the proposed active antenna, the problem of non-portability of VHF and UHF Horn antenna antennas has been solved. Finally, by analyzing the time domain, the stability of the circuit is examined, and the results of the stability test show that the system, including the antenna and the circuit, is stable. The antenna and the matching circuits are simulated by CST microwave studio and advanced design system, respectively.

Introduction: Skeletal muscles account for about 40% of the total body weight. Every year, hundreds of people lose at least part of their muscle tissue due to illness, war, and accidents. This can lead to disruption of activities such as breathing, movement, and social life. To this end, various therapeutic strategies such as medication therapy, cell therapy and tissue transplantation have been used or studied in muscle regeneration. However, there is no effective and well-defined clinical approach for treatment of muscle injuries and the severity of muscle injuries increase with age in most cases. Therefore, investigation for finding new and effective clinical approach for muscle regeneration is one of the most important issues in basic and clinical researches. Tissue engineering is considered as one of the promising and newest approach for skeletal muscle tissue regeneration and provides an appropriate model for personalized medicine and basic researches that can be used in personalized medicine and basic research. Besides biomaterials and cells, inducing factors are another element of tissue engineering. These factors influence epigenetic mechanisms and signaling pathway, thereby inducing proliferation, differentiation, and migration of cells used in muscle tissue engineering, and accelerates muscle formation in vitro. Recently, small molecules have been used as alternatives to growth factors or along with other inducing factors in muscle tissue engineering. Since they do not induce an immune reaction, penetrate easily to the cells and have a specific molecular target, therefore they have attracted much attention as the cost-effective inducing factors in tissue engineering. Conclusion: Taken together, the effective small molecules in muscle tissue engineering can be used with different biomaterial conditions (e. g. hydrogel, decellularized tissue, and synthetic scaffolds) in both in vivo and in vitro, resulting to production of cost effective and highly efficient engineered muscle tissues that help to achieve therapeutical goals of muscle tissue engineering. Herein, we describe tissue engineering and review the small molecules used in skeletal muscle tissue engineering.

In recent years, much more attentions have been focused on siRNA-based gene therapy. This approach is based on PTGS (Post-transcriptional gene silencing). Due to some defects in viral vectors, non-viral vectors have been used to deliver nucleic acids into target cells. Although, transfection efficiency in non-viral vectors is less than viral ones, but safety of non-viral vectors is much more. Characteristic features of siRNA, such as high compatibility, application in low doses and its versatility make it suitable in the gene therapy field. However, some challenges, such as stimulating immune system and Off-target silencing will be remain. In this review article, we express bottlenecks existing in siRNA delivery into target cells. According to the information, with further development of siRNA delivery in the future, it could be a promising approach in treatment for a variety of genetic diseases.

In recent few years fractals have been employed in conjunction with antennas to develop new applications. In this work, novel fractal geometry is introduced as a miniaturized microstrip patch antenna. Compared to a square patch antenna, the antenna shows an improvement of 68% size reduction. Furthermore, by applying of a new feeding method, refereed to here as the sleeve feeding, up to 27% impedance bandwidth is achieved as shown in the experiments.

This paper presents the results of a study on the radiation characteristics of a plasma triangular antenna in the VHF band (30-300MHz) applying the method of moment. Deriving the current distribution of the antenna, it shows the relationship between radiation characteristics of the plasma antenna and the plasma parameters. Both theoretical and numerical results indicate that if the plasma frequency is sufficiently higher than the operating frequency and the collision frequency is correspondingly low, the radiation treatment of the plasma antenna will be close to a metal one. Also the consequence of simulations reveals the proposed plasma antenna has better peak gain than the conventional plasma column on the operating band. The results of the current study are checked by using full wave HFSS simulator.

The class of Hybrid Linear and Circular Antenna Arrays is presented. The properties of linear and circular antenna arrays are combined to obtain hybrid array types: concentric circular, cylindrical, and coaxial cylindrical antenna arrays. These three types are defined, the expressions of their array factors are derived, their directivities and half power beam widths (HPBW) are simulated. The obtained plots are approximated by curve fitting. Different combinations of excitation currents (e.g. uniform, Chebyshev, Bessel, …) can exist on the elements of the same antenna array.