RU2080701C1 - Device which shows features of linear antennas - Google Patents

Abstract

FIELD: education. SUBSTANCE: device has emitter which is designed as serial circuit of high-frequency oscillator, rectangular funnel, electromagnetic lens, unit which alters masks, alternating masks, rotating rack and analyzing unit which has receiving funnel, detector and indicator. Said serial circuit is located base. Each alternating mask is designed as metal plate with hole which size and shape are determined by type of amplitude distribution to be modeled and electric size of antenna to be modeled. In addition it has dielectric strap which is designed as cylindrical prism which generatrix is determined by phase distribution to be modeled. EFFECT: possibility to model and demonstrate influence of aperture size, amplitude-phase distribution on beam pattern of continuous linear antenna. 3 dwg, 1 tbl

Description

 The invention relates to devices for training and can be used in the educational process to study the properties of linear antennas.

 Known devices for studying waveguide processes in an electromagnetic field. Such are educational devices in electromagnetism (ed. St. N 739630, BI 21, 1980, N 1008769, BI 12, 1983, N 1008771, BI 12, 1983 and others). Laboratory installations that solve the problems of demonstration in electrodynamics are described in the manuals: Shakhmaev N.M. and other demonstration experiments in electrodynamics. M. Enlightenment, 1973, as well as Lecture demonstrations in physics. Ed. V.I. Iverovich. M. Nauka, 1972, Yudkevich V.V. and other technical teaching aids and standard educational and laboratory equipment. M. High School, 1974.

 A common drawback of these devices when used to study antennas is the impossibility of modeling a number of properties and studying the dependences of the theory of antennas, for example, the effect of changes in the amplitude-phase distribution on emitting properties.

 Known devices for modeling antennas in the optical wavelength range (Fradin A.Z. Ryzhkov EV Measurement of the parameters of antenna-feeder devices. M. Communication, 1972, S. 282). These devices have several drawbacks when used as training devices: firstly, they simulate the properties of antennas in the optical range, as a result of which clarity is lost, since there is no demonstration of effects on a real scale, namely, in the radio range; secondly, they register for photographic materials, which leads to a sharp decrease in the efficiency of the demonstration and reduces the value of the device as a training one; thirdly, the implementation of simulation in the optical range is complex and requires precision accuracy in the manufacture of transparency elements, which is also an obstacle to the use of this device as a training one.

 The closest in technical essence is a training device for ed. St. N 1008769, CL G 09 B 23/22, BI 12, 1983, consisting of a radiator in the form of sequentially placed on the basis of a microwave generator, a rectangular waveguide, a pyramidal horn, an electromagnetic lens, an optical element (mask) in the form of a packet of twisted rectangular waveguides and an analyzer in the form of a pyramidal horn , rectangular waveguide, detector and indicator.

 The specified training device in optics is intended for modeling in the microwave range of electromagnetic waves the action of an optically active substance on the polarization of light radiation passing through it. This is achieved by using an optical element in the form of a packet of twisted waveguides, which rotates the plane of polarization of the wave incident from the horn of the emitter.

The specified training device can be used as a demonstration and to study the properties of antennas. However, a number of its shortcomings significantly limit this possibility:
the device does not allow modeling and studying the effect of the amplitude-phase distribution on the antenna pattern,
the device does not allow modeling and studying the influence of the size of the antenna on its radiation pattern.

 The purpose of the invention is to ensure the clarity and efficiency of the study of the influence of aperture size and amplitude-phase distribution on the directivity pattern of a continuous linear antenna in the radio range.

(2b размер раскрыва рупора излучателя в H-плоскости, E(x) нормированное амплитудное распределение, моделируемое n-ой маской) с диэлектрической накладкой переменной толщины, определяемой выражением

фазовое распределение, моделируемое n-ой маской).The problem is solved in that in a training device for demonstrating the properties of linear antennas containing an emitter in the form of sequentially placed on the basis of a microwave generator, a rectangular waveguide, a pyramidal horn, an electromagnetic lens, a mask installed in the lens aperture, and an analyzer in the form of a pyramidal horn, a rectangular waveguide , detector and indicator, the emitter is mounted on a rotary rack equipped with a reference scale of the angle of rotation, on the outer flange of the pyramidal horn of the emitter is installed Leno device shift masks having N rectangular apertures, are mounted in the mask, each of which is made of a metal plate with an opening, whose shape corresponds to the expression

(2b size of the aperture of the horn of the emitter in the H-plane, E (x) normalized amplitude distribution modeled by the nth mask) with a dielectric patch of variable thickness, defined by the expression

phase distribution modeled by the nth mask).

 Some of the distinguishing features are known in other sets of features. So it is known the use of a rotary rack for measuring the antenna pattern. The use of replaceable masks for modeling antennas in the optical range is also known (Fradin A.Z. Ryzhkov E.V. Measurement of the parameters of antenna-feeder devices, M. Svyaz, 1972, p. 282). These masks are made in the form of glass optically translucent plates or plates with holes. The device performs registration of simulation results on a photographic plate. Compared with the claimed device, this is not a demonstration of the properties of antennas, but their modeling, based on a mathematical analogy of the processes of radiation of antennas and the properties of the Fourier transform in optical systems.

 modeling in the optical range has a number of features: modeling is possible for apertures whose size in wavelengths is many times greater than the size of real radio-frequency antennas; in the manufacture of masks, it is necessary to perform the thickness of the glass substrates with micron accuracy; in the manufacture of masks, the effect of non-linearity of the characteristic curve of the photographic material is affected. These features determined that the optical modeling method, having limited capabilities, did not find application in engineering practice.

 Figure 1 shows the functional diagram of the device; figure 2 an example of the implementation of the n-th interchangeable mask simulating the amplitude distribution; figure 3 an example of the implementation of a removable mask with a dielectric pad simulating the amplitude-phase distribution.

 The training device of FIG. 1 contains an emitter consisting of a high-frequency generator 1, a rectangular waveguide 2, a horn 3, an electromagnetic lens 4, a device for changing masks 5, replaceable masks 6, a rotary stand 7, and an analyzer consisting of a receiving horn 8, detector 9 and indicator 10. Mask 6 is made in the form of a metal plate 11 with a dielectric pad 12 (figure 3).

 The operation of the device is as follows.

 The high-frequency generator 1 excites a propagating electromagnetic wave in a rectangular waveguide 2. The horn 3 and the electromagnetic lens 4 form a common-mode electromagnetic field with a certain intensity E (x, y) on the shadow surface of the lens 4, which, in the case of a horn of rectangular cross section, has a uniform distribution of amplitudes in the E plane and a cosine distribution in the H. plane. To demonstrate the various properties of the antenna, it is necessary to provide the possibility of the required changes in the distribution of the floor in the aperture, corresponding to the demonstrated effect. This is provided by interchangeable masks 6 installed before opening the horn in the mask changing device 5.

 To demonstrate the influence of the antenna size and the amplitude distribution of the field on the radiation pattern, it is necessary to ensure the formation of various amplitude distributions in the plane E. Without using a mask, this distribution is uniform. Figure 2 shows the mask 6 used in this case, which is a metal plate 11 with a hole corresponding to the simulated amplitude distribution. In this case, there is no dielectric overlay, because we assume that Φ (x) = 0; therefore, l (x) 0.

видом моделируемого амплитудного распределения E(x) и связан с ним соотношением:

Таким образом, используя маски с различными по форме отверстиями, можно осуществить моделирование излучения непрерывных линейных антенн с различными размерами и амплитудными распределениями. В качестве примера в таблице приведены полученные по (1) амплитудные распределения и размеры отверстия для случая 2a 2b 200 мм, Lx 180 мм для трех различных формируемых амплитудных распределений.The size of the plate corresponds to the opening of the speaker 3 and is 2a x 2b. The shape of the hole is determined: size Lx by the electrical size of the simulated antenna, profile

the form of the simulated amplitude distribution E (x) and is associated with it by the ratio:

Thus, using masks with holes of various shapes, it is possible to simulate the radiation of continuous linear antennas with different sizes and amplitude distributions. As an example, the table shows the amplitude distributions obtained from (1) and the hole sizes for the case 2a 2b 200 mm, Lx 180 mm for three different generated amplitude distributions.

Амплитудное распределение по-прежнему определяется формой отверстия металлической пластины. Выбором пластин с одинаковой формой отверстия и с разными профилями накладок осуществляется демонстрация влияния фазового распределения на диаграмму направленности. Например, использование накладки в форме призмы моделирует излучение антенны с линейным фазовым распределением, а накладка с параболическим профилем моделирует влияние квадратичной фазовой ошибки. Например, при моделировании линейной фазовой ошибки, приводящей к повороту диаграммы направленности на 5^o при размере Lx 180 мм, λ = 30 мм и использовании полистирола с ε = 2,5, диэлектрическая накладка 12 имеет вид призмы с толщиной, изменяющейся по линейному закону от 0 до 27 мм на краю раскрыва. Измерение диаграмм направленности для смоделированного амплитудно-фазового распределения осуществляется определением показаний индикатора 10 при различных углах поворота излучателя на поворотной стойке 7.The demonstration of the influence of the phase distribution on the antenna pattern is carried out by installing dielectric plates 12 of variable thickness on metal plates 11 (Fig. 3). In this case, the electromagnetic wave, passing through various sections of the lining, acquires phase shifts of various sizes. The thickness of the patch is determined by the phase distribution Φ (x) simulated by the mask:

The amplitude distribution is still determined by the shape of the hole of the metal plate. The choice of plates with the same hole shape and with different cover profiles demonstrates the effect of the phase distribution on the radiation pattern. For example, using a prism-shaped overlay simulates the radiation of an antenna with a linear phase distribution, and a parabolic overlay simulates the effect of a quadratic phase error. For example, when simulating a linear phase error, which leads to a rotation of the radiation pattern by 5 ^° with a size of Lx 180 mm, λ = 30 mm and the use of polystyrene with ε = 2.5, the dielectric pad 12 has the form of a prism with a thickness that varies linearly from 0 to 27 mm at the edge of the aperture. The radiation patterns are measured for the simulated amplitude-phase distribution by determining the readings of indicator 10 at various angles of rotation of the emitter on the rotary stand 7.

Отверстие в маске симметрично относительно оси x и определяется кривой y(x), его максимальный размер в плоскости xoz равен Lx. В этой плоскости ДН определяется эквивалентным амплитудным распределением на участке -Lx/2≅x≅Lx/2:

Принимая, что будем формировать нормированное амплитудное распределение (E_max(x)= 1), а маска должна быть наиболее эффективной

, имеем E_o= π/4b. Тогда кривая края отверстия имеет вид:

Выражение (2) получено из следующих соображений. Плоская волна, падающая на установленную перед отверстием диэлектрическую цилиндрическую накладку с образующей кривой l(x) при движении от плоскости z=z₀ до плоскости z=0, проходит путь, электрическая длина которого равна

и приобретает дополнительную фазовую задержку

. Отбрасывая несущественную постоянную фазовую добавку, получаем выражение для профиля накладки

, которая обеспечивает получение заданного фазового распределения в раскрыве. Для получения накладки минимальной толщины целесообразно брать Φ(x)_min = 0.
Учебный прибор может быть выполнен следующим образом. В качестве генератора 1 используется серийный генератор стандартных сигналов сантиметрового или миллиметрового диапазона волн или малогабаритный генератор в виде волноводной секции с отвердительным активным элементом в виде, например, диода Ганна. При помощи прямоугольного волновода со стандартным фланцем генератор соединен с пирамидальным рупором, размер которого определяется величиной моделируемых антенн и может составлять: размер апертуры рупора (10...15)λx(10...15)λ, где λ длина волны, длина рупора (20...30)λ. В раскрыве рупора установлена диэлектрическая осесимметричная линза, изготовленная, например, из полистирола. Линза установлена выпуклой стороной внутрь рупора. На внешнем фланце рупора излучателя установлено устройство смены масок в виде барабана с N прямоугольными отверстиями, в которые установлены маски.Expression (1) is obtained as follows. We believe that the field in the mouth of the horn where the mask will be installed has the same form as the field in the exciting waveguide:

The hole in the mask is symmetrical about the x axis and is determined by the y (x) curve, its maximum size in the xoz plane is Lx. In this plane, the DN is determined by the equivalent amplitude distribution in the section -Lx / 2≅x≅Lx / 2:

Assuming that we will form a normalized amplitude distribution (E _max (x) = 1), and the mask should be the most effective

, we have E _o = π / 4b. Then the curve of the edge of the hole has the form:

Expression (2) is obtained from the following considerations. A plane wave incident on a dielectric cylindrical plate installed in front of the hole with a generatrix curve l (x) moving from the plane z = z ₀ to the plane z = 0 passes a path whose electric length is

and acquires an additional phase delay

. Discarding the insignificant constant phase addition, we obtain an expression for the overlay profile

, which provides a given phase distribution in the aperture. To obtain the minimum thickness overlays, it is advisable to take Φ (x) _min = 0.
The training device can be performed as follows. As a generator 1, a serial generator of standard signals of a centimeter or millimeter wave range or a small-sized generator in the form of a waveguide section with a curing active element in the form of, for example, a Gunn diode is used. Using a rectangular waveguide with a standard flange, the generator is connected to a pyramidal horn, the size of which is determined by the size of the modeled antennas and can be: the size of the aperture of the horn (10 ... 15) λx (10 ... 15) λ, where λ is the wavelength, length of the horn (20 ... 30) λ. In the aperture of the horn, a dielectric axisymmetric lens is installed, made, for example, of polystyrene. The lens is mounted with the convex side inside the horn. A mask changer in the form of a drum with N rectangular holes in which masks are installed is installed on the outer flange of the speaker horn.

 Masks are metal plates or foil fiberglass plates. All plates have the same overall and installation dimensions. The dimensions of the plates are equal to the mouth of the mouth. If necessary, a dielectric patch is installed on the inner surface of the plate by gluing. Holes were made in the plates, and in the case of using a foil-coated dielectric, metallization is removed in the areas corresponding to the hole. To reduce the effect of reflections on metallized areas, plates of radar absorbing material can be installed on the inside. An emitter with replaceable masks is mounted on a rotary base for measuring the angular dependences of the radiated field, i.e. radiation patterns. The analyzer is made in the form of a horn, for example, a measuring horn from a set of measuring antennas, an amplitude detector and an indicator in the form of a measuring amplifier, for example, a serial measuring amplifier with a digital output of type B 8-7, can be used. Demonstration of the properties of antennas is carried out by measuring the MD with various masks.

 The use of a training device is possible both for the purpose of a lecture demonstration device, and in a laboratory workshop on the course "Antennas and microwave devices." Using the device in a training laboratory will reduce the composition of laboratory facilities due to the possibility of conducting several laboratory work on this device, unify laboratory equipment and thereby facilitate the organization of a laboratory workshop using the front-end method.

Claims (1)

A training device for demonstrating the properties of linear antennas, containing an emitter in the form of a sequentially placed on the basis of a microwave generator, a rectangular waveguide, a pyramidal horn, an electromagnetic lens and a mask installed in the aperture of this lens, and an analyzer in the form of a pyramidal horn, a rectangular waveguide, detector and indicator, characterized in that the emitter is mounted on a rotary stand equipped with a reporting scale of the angle of rotation, the pyramidal horn of the emitter is equipped with an external flange we have introduced a device for changing masks, which is installed on the outer flange and has N holes in which N masks are installed, each of which is a hole made in a metal plate with a dielectric patch of variable thickness, and the shape of the hole of the nth mass corresponds to expression

and the variable thickness of the dielectric lining of the nth mask is determined from the expression

where 2b is the size of the aperture of the pyramidal horn of the emitter in the H plane;
E _n (x) is the normalized amplitude distribution of the simulated nth mask of the linear antenna;
Φ _n (x) is the phase distribution modeled by the nth mask of the linear antenna;
λ is the length of the electromagnetic wave;
ε _n is the dielectric constant of the dielectric material of the nth mask.

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