Waveguide filters are key elements present in many microwave and millimeter-wave communication systems. In recent times, ever-increasing efforts are being devoted to the development of automated computer-aided design (CAD) tools of such devices. In this paper, a novel CAD tool based on modal analysis methods, which improves the efficiency and robustness of the classical aggressive space-mapping technique, is presented for those purposes. The use of a new segmentation strategy and the hybridization of a specific combination of several well-known optimization algorithms is proposed. The CAD tool has been successfully validated with the practical design of several H-plane coupled cavity filters in a rectangular waveguide for space and communication applications. A filter prototype for local multipoint distribution systems operating at Ka-band, and two tunable H-plane filters with tuning posts operating at 11 and 13 GHz, have been successfully designed, manufactured, and measured.

Fast automated design of waveguide filters using aggressive space mapping with a new segmentation strategy and a hybrid optimization algorithm

A new and efficient hybrid mode-matching method is presented for the analysis of arbitrarily shaped inductive obstacles and/or discontinuities in a rectangular waveguide. The irregular region with obstacles and/or discontinuities is characterized using a full-wave hybrid spectral/numerical open-space technique expanding the fields in cylindrical wave functions. Next, a full-wave mode-matching procedure is used to match the cylindrical wave functions to guided modes in all ports and a generalized scattering matrix for the structure is finally obtained. The obstacles can be metallic or dielectric with complex permittivities and arbitrary geometries. The structure presents an arbitrary number of ports, each one with different orientation and dimensions. The accuracy of the method is validated comparing with results for several complex problems found in the literature. CPU times are also included to show the efficiency of the new method.

A new hybrid mode-matching/numerical method for the analysis of arbitrarily shaped inductive obstacles and discontinuities in rectangular waveguides

This paper reviews the history and present state of finite-element methods, as applied to electromagnetic-field problems in the microwave range (including element definitions and error estimation, guided wave propagation, scattering and antenna problems). It provides a selective bibliography, current as of the first months of 1996, with annotations and evaluative comments on the works surveyed. It briefly notes the capabilities of the finite-element method, and estimates how fully they have been realized to date. Some conjectures on the future of finite-element methods are also hazarded.

Finite-element methods in microwaves: a selected bibliography

A numerical method is formulated for the analysis of H-plane waveguide junctions with arbitrary cross sections. The junctions are loaded with arbitrarily shaped dielectric or ferrite. The method is a combination of the finite-element method and the boundary-element method, and is applied to the regions with and without dielectric or ferrite, respectively. To show the validity and usefulness of the method, a lossy dielectric post and a ferrite slab in a rectangular waveguide are investigated in detail, and the computed results are compared with earlier theoretical and experimental results. >

Numerical analysis of H-plane waveguide junctions by combination of finite and boundary elements

A numerical method for the analysis of waveguide discontinuities is proposed. The approach is based on the coupling of the finite-element and boundary-element methods. The respective merits of these methods are extracted to yield a much faster solution and to enhance computation efficiency. A general procedure is described using quadratic elements approximation, and the validity and efficiency of the method is demonstrated in the cases of a three-port H-plane ferrite waveguide Y junction and of a right-angle corner bend with and without dielectric loading. Comparisons of the present results with those obtained using the finite-element approach are made and shown to be in good agreement. An experimental result is also presented. The validity of the technique can be easily verified. >

Waveguide discontinuity analysis with a coupled finite-boundary element method

The equivalent circuit parameters of rectangular waveguide H-plane junctions, bends and obstacles may be found by a two-dimensional finite element method. Results are presented for perfectly conducting and dielectric obstacles, and for a waveguide bend. Good agreement is obtained with previously published results.

Finite element analysis of H-plane rectangular waveguide problems

Mahogany is a Meliaceae family exotic plant that includes three species: Swietenia macrophylla king, S mahogany L. Jacq., and S. humulis Zucc. This genus is predominantly found in the humid zone of the New World and the Amazon region of South America. The purpose of this review article is to look at its taxonomical classification, vernacular names, pharmacological activities and its phytochemistry. Scientific studies have found that the crude extract from S. macrophylla seeds has antibacterial, anti-malaria, anti-hepatitis, anti-diarrheal, antioxidant, anti-diabetic, anti-inflammatory, anti-mutagenic, antinociceptive, and anticancer properties. Phytochemical investigations have shown that limonoids and their derivatives are the major constituents of Swietenia macrophylla.

/pdf/phytochemistry-and-pharmacological-activities-of-swietenia-bo0ebkgy.pdf

Phytochemistry and Pharmacological Activities of Swietenia macrophylla King (Meliaceae)

Meliaceae is a family of 50 genera with 1400 species that are predominantly found in tropical parts of the third world. Because of its timber and calorific value, members of this family are commercially valuable. Mahogany is a Meliaceae family exotic plant that includes three species: Swietenia macrophylla king, S mahogany L. Jacq., and S. humulis Zucc. Mahogany's distribution in India is limited to the Western and Eastern Ghats. This genus is predominantly found in the humid zone of the New World and the Amazon region of South America. The purpose of this review article is to look at its botanical description, geographical distribution, ecological range, cultivation and collection methods, wood characteristics, wood uses, therapeutic uses, seed cultivation and propagation practices, and wood characteristics, wood uses, and therapeutic uses.

https://doi.org/10.36347/sajp.2022.v11i01.003

Collection and Cultivation of Swietenia macrophylla King

Withania somnifera is the most valuable herbaceous plant, also known as Ashwagandha used in the traditional systems of Indian medicine having many therapeutic effects. It is obtained from the dried roots and stems of Withania somnifera belonging to family Solanaceae. The active chemical constituents of Withania somnifera are withaferin A, withanolide A, withasomniferin-A, isopelletierine, withasomidienone, tropine, withanone, cuscohygrine, anaferine, hygrine, anahygrine, somniferine, mesoanaferine, etc. It is used as a liver tonic, aphrodisiac, in asthma, emaciation, in bronchitis and ulcers. It has life prolonging, rejuvenating effect & also used for the treatment of insomnia, anxiety, skin disease, nervous exhaustion, impotency, enhancing memory and insulin secretion etc. Marketed formulations of Ashwagandha are Ashwagandharista, Himalaya Ashwagandha, Stresswin, Stresscom, Inlife Ashwagandha capsules, Himalaya massage oil, Ancient Apothecary, KSM 66 Ashwagandha, Vigomax, Baidyanath Ashwagandha Amrita 450 ml, Vital plus, Amrutha kasthuri and Brento etc. To maintain the quality of marketed formulations validation should be done. Different validation parameters such as LOQ, LOD, range & linearity, accuracy, ruggedness and specificity have been studied. Ashwagandha is in demand as a good health promoter is expanding in global market. Many efforts were undertaken to develop a better Withania somnifera variety with a specific chemotype. HPTLC (High performance thin layer chromatography) is most important in evaluating the quantity and quality of herbal drug. This technique is modern & effective form of TLC which is used for qualitative and quantitative analytical determination of analytes. It is the simple, rapid, precise, specific, robust and accurate technique. The effect of different extraction methods on marker compound Withaferin-A & other than Withaferin-A, effect of different climatic zones on phytochemical profile of Withania somnifera, different mobile ........

Quality Control of Withania somnifera and its Marketed Formulations by Validation through High Performance Thin Layer Chromatography

Withania somnifera, is a well-known medicinal herb in the Solanaceae family that has been used for over 3,000 years all over the world. It's also known as "Indian ginseng" and winter cherry, and it's an Ayurvedic and indigenous medicine. The fragrance is described by the word "Withania somnifera", which means "horse." In India, the Middle East, and portions of Africa, it is grown. Isopellertierine, anferine, withanolides, withaferins, and withanolides are the main components of Withania somnifera. It has the ability to treat a variety of health conditions, including anxiety, stress, antioxidant, anti-inflammatory, and antidepressant properties, as well as increase fertility and testosterone in males and regulate brain activities. Despite the fact that Withania somnifera has been used for a long time, further clinical trials are needed to improve therapeutic efficacy. 

A literature review on pharmacological activities of Withania somnifera

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