FORMATION OF A SCANNING ANTENNA BASED ON A HALF-WAVE DIPOLE

Рассматривается полуволновый диполь с установленным рефлектором, который позволяет производить сканирование пространства с использованием вращения рефлектора вокруг диполя. Для полученной конструкции производилось моделирование основных параметров, которые показали высокую стабильность при различных положениях рефлектора, постоянное значение коэффициента направленного действия, ширины главного лепестка. Изменение направления излучения совпадает с текущим положением рефлектора. По сравнению с ситуацией, когда у антенны отсутствовал рефлектор, КНД антенны увеличился, так как произошла фокусировка электромагнитных волн. Коэффициент полезного действия и передне-заднее отношение сохраняют высокие значения во всем диапазоне рабочих частот. Применение предложенной конструкции позволяет упростить конструкцию сканирующих антенн, так как для ее реализации требуются лишь полуволновой диполь и плоский рефлектор, установленный на малом расстоянии от источника излучения. В процессе управления характеристиками требуется вращать рефлектор вокруг диполя, при этом диполь остается неподвижным, что позволяет повысить эффективность предложенной конструкции, так как не требуется формировать сложных антенных систем или устанавливать комбинацию из нескольких антенн для фокусировки излучения в одном направлении от источника The article discusses a half-wave dipole with an installed reflector, which allows scanning space using the rotation of the reflector around the dipole. For the resulting structure, we simulated the main parameters, which showed high stability at various positions of the reflector, a constant value of the directivity factor, and the width of the main lobe. The change in the direction of radiation coincides with the current position of the reflector. Compared to the situation when the antenna did not have a reflector, the directivity of the antenna increased since the focusing of electromagnetic waves took place. The efficiency and the front-to-back ratio remain high throughout the entire operating frequency range. The use of the proposed design makes it possible to simplify the design of scanning antennas since the implementation of the proposed design requires only a half-wave dipole and a flat reflector installed at a short distance from the radiation source. In the process of controlling the characteristics, it is required to rotate the reflector around the dipole, while the dipole remains stationary, which makes it possible to increase the efficiency of the proposed design, since it is not required to form complex antenna systems or install a combination of several antennas to focus radiation in one direction from the source

THE TREATENT OF PRIMARY MULTIPLE CANCER IN A PATIENT WITH A KIDNEY GRAFT. CLINICAL INCIDENCE

Treatment of tumors in kidney recipients is not an easy task, due to lifelong immunosuppression. The leading place among all graft tumors is skin cancer - 31%, and the 3rd place is occupied by tumors of the genitourinary system (0.35.8%). The main method of treating skin cancer is surgical, which is difficult to perform in some localities. An alternative method is radiation therapy. The tumor in the graft is rare. The method of treating a tumor of this localization is surgical, which can lead to nephrectomy of the graft. Radiofrequency-assisted graft resection is an original treatment method. Its use provides good immediate and long-term treatment results. Patient B., born in 1977, 20.10.2016 was diagnosed with a tumor in kidney graft T1aN0M0 (stage I). Allotransplantation of the kidney to the left iliac vessels from 15.01.2012. When choosing the method, there were difficulties: an obese patient, graft eventration in anamnesis, according to MSCT, intestinal loops are located around the kidney graft, and fibrous changes around the kidney graft. Laparoscopic radiofrequency - assisted renal graft resection was chosen as the method of treatment. Operation duration-120 minutes, blood loss-100 ml. The postoperative period was uneventful. Currently, there are no signs of relapse. In June 2019-the appearance of a skin formation in the area of the left auricle, histologically-squamous cell cancer, G III. From 12.07.2019-short-focus radiation therapy with ROD 3 G, SOD 54 G. The treatment was carried out satisfactorily. In October 2019-a similar formation on the skin of the left cheek. From 14.11.2019-short-focus radiation therapy, ROD 2.75 G, SOD 55 G. The treatment was carried out satisfactorily. Currently, there are no signs of a recurrence of the tumor. The use of modern techniques and equipment makes it possible to perform treatment of primary multiple tumors in patients after kidney transplants with satisfactory cosmetic, functional and oncological results.

Experiment with a diffractive lens with a fixed focus position at several given wavelengths

The paper presents results of the experimental investigation of “spectral” diffractive lenses the same focus position for several given wavelengths. Two spectral diffractive lenses designed to focus radiation of three and five specified wavelengths in the visible spectrum were investigated. Using a method of direct laser writing in photoresist with iterative correction of writing parameters, we fabricated a diffractive microrelief of the spectral lenses with the height deviation from the designed relief of less than 30 nm. Using a pinhole located at the focus of the fabricated lenses, we estimated the operation wavelengths. The point spread functions of the spectral lenses at the designed wavelengths were measured with the use of a tunable laser. The imaging properties of the spectral lenses were illustrated by the images of a reference color table.