Antenna array of waveguide elements with dielectric phasing sections

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Introduction

In recent years, there has been a rapid growth in the use of drones in civil and military applications [1]. In addition, satellite communication technologies are constantly being improved [2–5]. As a result, there is a need for the development and improvement of high-speed satellite communication terminals of mobile and airborne basing, as well as satellite communication equipment with a high degree of secrecy of operation, emitting wideband signals, the power spectral density of which, measured at the input of receiving devices of radio control complexes, should be significantly lower than the power spectral density of noise, due to the following factors:

• Provision of reliable and high-quality communications to military and civilian users;
• Development of the domestic element and technological base, import replacement;
• Demand of the emergency services for compact information transmission and reception systems affordable to motorists, construction workers, geologists, fishermen, hunters, tourists, etc.;
• Need to develop satellite-based systems for controlling military and civilian equipment;
• Development of the precision agriculture program.

1. Antenna element model

Fig. 1 shows a model of an antenna element based on a circular waveguide with an inner diameter of 18 mm and a dielectric plate whose plane is oriented at an angle of 45° to the force lines of the electric field strength vector. The circular waveguide is powered with a linear-expanding transition from the rectangular waveguide to the square waveguide, completely filled with polystyrene as dielectric, to realize the necessary spatial orientation of the plate in the circular part of the waveguide, as well as to reduce reflections from the junction of the square and circular waveguide.

 

Fig. 1. Antenna design, including a linear junction in the E-plane and a phase-shifting section in a circular waveguide

Рис. 1. Конструкция антенны, включающей линейный переход в Е-плоскости и фазосдвигающую секцию в круглом волноводе

 

2. Modeling results

Figs. 2–4 summarize the basic characteristics of the antenna device. Fig. 2 shows the input characteristics of the antenna device; Fig. 3 shows its volumetric radiation patterns; Fig. 4 illustrates the quality of the polarization ellipse of the main lobe of the antenna pattern.

 

Fig. 2. Input characteristics of the antenna element (Fig. 1)

Рис. 2. Входные характеристики антенного элемента (рис. 1)

 

Fig. 3. Antenna pattern on the right circular polarization: a – pattern on the right circular polarization at a frequency of 10,95 Hz; b – pattern on the right circular polarization at a frequency of 11,7 Hz

Рис. 3. ДН антенны на правой круговой поляризации: а – ДН на правой круговой поляризации на частоте 10,95 Гц; б – ДН на правой круговой поляризации на частоте 11,7 Гц

 

Fig. 4. Quality of the polarization ellipse, section in the angular-local plane: a – axial ratio of the polarization ellipse at a frequency of 10,95 GHz; b – axial ratio of the polarization ellipse at a frequency of 11,7 GHz

Рис. 4. Качество поляризационного эллипса, разрез в угло-местной плоскости: а – осевое отношение эллипса поляризации на частоте 10,95 ГГц; б – осевое отношение эллипса поляризации на частоте 11,7 ГГц

 

Fig. 3 shows that the amplitude waveguide element’s radiation patterns are practically axisymmetric, in contrast to the deformed radiation patterns of elements in the form of two-turn Archimedean spirals (however, the latter are much simpler to manufacture using the technology of PCB production, which is very important in the manufacture of multi-element phased arrays).

At the lower frequency of 10,95 GHz of the analyzed range, the axial polarization ellipse ratio does not exceed 3 dB in the 90° wide angle sector (Fig. 4, a); at the upper frequency of 11,7 GHz of the analyzed range, the polarization ellipse ratio does not exceed 3 dB in almost the entire hemispherical space (Fig. 4, b).

Fig. 5 shows the volume patterns of a linear antenna array of 32 elements shown in Fig. 1, arranged equidistantly with a period of 21 mm, fed by an in-phase and equal-amplitude power divider.

 

Fig. 5. Volumetric radiation patterns of an in-phase and equal-amplitude linear antenna array of 32 waveguide elements with phasing sections located with a period of 21 mm

Рис. 5. Объемные диаграммы направленности синфазной и равноамплитудной линейной антенной решетки из 32 волноводных элементов с фазирующими секциями, расположенных с периодом 21 мм

 

Figs. 6 and 7 show the radiation patterns in the azimuthal and angular-local planes of a linear antenna array of 32 waveguide elements with phasing sections, arranged with a period of 21 mm, powered by an in-phase and equal-amplitude power divider.

 

Fig. 6. Radiation patterns in the azimuthal plane of an in-phase and equal-amplitude linear antenna array of 32 waveguide elements with phasing sections located with a period of 21 mm

Рис. 6. Диаграммы направленности в азимутальной плоскости синфазной и равноамплитудной линейной антенной решетки из 32 волноводных элементов с фазирующими секциями, расположенных с периодом 21 мм

 

Fig. 7. Radiation patterns in the angular-local plane of an in-phase and equal-amplitude linear antenna array of 32 waveguide elements with phasing sections located with a period of 21 mm

Рис. 7. Диаграммы направленности в угло-местной плоскости синфазной и равноамплитудной линейной антенной решетки из 32 волноводных элементов с фазирующими секциями, расположенных с периодом 21 мм

 

The level of the side lobes of the radiation pattern in the azimuthal plane (Fig. 6) at all frequencies is better than that of the in-phase and equal-amplitude opening of equivalent dimensions (–13,2 dB).

The minimum width of the radiation pattern in the angular-local plane is about 68°; when the linear sublattices are arranged as part of a rectangular antenna array in the angular-local plane, the width of the radiation pattern of the linear sublattice, as an element of a planar phased array, expands due to the reciprocal effect of the elements of neighboring linear arrays.

3. Linear and planar antenna arrays based on in-phase and equal-amplitude power divider

Below we consider linear and planar antenna arrays based on an in-phase and equal-amplitude 1:32 power divider and antenna elements based on square waveguides with internal dimensions of 14 × 14 mm² with beveled internal corners, in order to reduce losses, as well as to take into account the possible manufacturing technology of metal milling.

Fig. 8 shows a model of a linear antenna array of 32 waveguide elements with phasing sections, fed by an equal-amplitude and in-phase power divider. The length of the antenna element is 40 mm. The period of the elements arrangement in the linear antenna array is 21 mm.

 

Fig. 8. Model of a linear antenna array of 32 elements with an in-phase and equal-amplitude power divider: a – appearance of a linear in-phase antenna array of 32 elements; b – polystyrene liner in the power divider and in the antenna elements. The thickness of the dielectric in the divider is 1,5 mm. The thickness of the phasing plates in square waveguides is 3 mm; c – period of arrangement of elements in a linear antenna array – 21 mm; d – longitudinal section of a linear antenna array with a power divider (fragment)

Рис. 8. Модель линейной антенной решетки из 32 элементов с синфазным и равноамплитудным делителем мощности: а – внешний вид линейной синфазной антенной решетки из 32 элементов; б – полистироловый вкладыш в делителе мощности и в антенных элементах. Толщина диэлектрика в делителе – 1,5 мм. Толщина фазирующих пластин в квадратных волноводах – 3 мм; в – период расположения элементов в линейной антенной решетке – 21 мм; г – продольный разрез линейной антенной решетки с делителем мощности (фрагмент)

 

A model of a planar antenna array composed of the 16 linear antenna arrays shown in Fig. 8 is shown in Fig. 9. The position period of linear lattices is 15 mm (its value was reduced from 21 to 15 mm in order to reduce the level of side lobes in wide-angle scanning in the angular-local plane).

 

Fig. 9. Model of a flat antenna array composed of 16 linear antenna arrays: a – flat antenna array of 32 × 16 elements, composed of 16 linear antenna arrays. Aperture dimensions – 665,5 × 238 mm²; b – period in the angular-local plane – 15 mm (reduced in order to reduce the level of side lobes during wide-angle scanning); c – phased array with 32 × 16 elements with power dividers located horizontally. The phased array aperture is tilted at an angle of 37,5 degrees in the elevation plane. The height of the modified phased array is 175 mm. The depth of the phased array with power dividers is 262 mm. Headlight array width – 665,5 mm

Рис. 9. Модель плоской антенной решетки, составленной из 16 линейных антенных решеток: а – плоская антенная решетка из 32 × 16 элементов, составленная из 16 линейных антенных решеток. Размеры апертуры – 665,5 × 238 мм²; б – период в угло-местной плоскости – 15 мм (уменьшен с целью снижения уровня боковых лепестков при широкоугольном сканировании); в – ФАР с 32 × 16 элементов с делителями мощности, расположенными горизонтально. Апертура ФАР наклонена на угол 37,5 градусов в угло-местной плоскости. Высота модифицированной ФАР – 175 мм. Глубина ФАР с делителями мощности – 262 мм. Ширина ФАР – 665,5 мм

 

The vertical plane radiation patterns of a planar antenna array composed of 16 linear antenna arrays are shown in Fig. 10.

 

Fig. 10. Radiation patterns in the vertical plane of a flat antenna array composed of 16 linear antenna arrays: a – pattern in the vertical plane of the phased array 32 × 16 elements when emitting normal to the phased array aperture, frequency – 10,95 GHz; b – pattern in the vertical plane of the phased array 32 × 16 elements with radiation at an angle of 37,5 degrees to the normal to the phased array aperture, frequency – 10,95 GHz; c – pattern in the vertical plane of the phased array 32 × 16 elements when emitting normal to the phased array aperture, frequency – 11,325 GHz; d – pattern in the vertical plane of the phased array 32 × 16 elements with radiation at an angle of 37,5 degrees to the normal to the phased array aperture, frequency – 11,325 GHz; e – pattern in the vertical plane of the phased array 32 × 16 elements when emitting normal to the phased array aperture, frequency – 11,7 GHz; f – pattern in the vertical plane of the phased array 32 × 16 elements with radiation at an angle of 37,5 degrees to the normal to the phased array aperture, frequency – 11,7 GHz

Рис. 10. Диаграммы направленности в вертикальной плоскости плоской антенной решетки, составленной из 16 линейных антенных решеток: а – ДН в вертикальной плоскости ФАР 32 × 16 элементов при излучении по нормали к апертуре ФАР, частота – 10,95 ГГц; б – ДН в вертикальной плоскости ФАР 32 × 16 элементов при излучении под углом 37,5 градуса к нормали к апертуре ФАР, частота – 10,95 ГГц; в – ДН в вертикальной плоскости ФАР 32 × 16 элементов при излучении по нормали к апертуре ФАР, частота – 11,325 ГГц; г – ДН в вертикальной плоскости ФАР 32 × 16 элементов при излучении под углом 37,5 градуса к нормали к апертуре ФАР, частота – 11,325 ГГц; д – ДН в вертикальной плоскости ФАР 32 × 16 элементов при излучении по нормали к апертуре ФАР, частота – 11,7 ГГц; е – ДН в вертикальной плоскости ФАР 32 × 16 элементов при излучении под углом 37,5 градуса к нормали к апертуре ФАР, частота – 11,7 ГГц

 

Conclusion

We shall summarize the results of the simulation of a planar phased array with waveguide elements with circular polarization.

In the considered phased array design, positioning of the main lobe of the radiation pattern in the azimuthal plane is carried out by mechanical rotation of the antenna system. The rejection of two-axis electronic scanning is chosen based on the considerations of reducing phase shifters (or high-frequency switches) and reducing the cost of the phased array.

The height of the phased array with horizontal arrangement of power dividers, consisting of 32 × 16 elements, is 175 mm. The depth of the phased array is 262 mm. The width of the phased array is 665,5 mm.

The gain at 10,95 GHz is 32,5 dB (normal) and 31,2 dB when the beam is deflected ±37,5° in the angular-local plane (excluding losses in the Rotman lens and commutator).

The gain at 10,95 GHz is 32,5 dB (normal) and 31,2 dB when the beam is deflected ±37,5° in the angular-local plane (excluding losses in the Rotman lens and commutator).

At the maximum deviation of the main lobe from the normal, the level of the side lobes in the vertical (angular-local plane) increases to the level of –11,4 dB, which slightly exceeds the sidelobe level at in-phase and equal-amplitude field distribution in the phased array aperture (–13,2 dB).

Funding

The work was carried out with the financial support of the Ministry of Science and Higher Education of the Russian Federation within the framework of the state assignment (project no. FZGM-2023-0011).

About the authors

Yuri G. Pasternak

Voronezh State Technical University

Email: pasternakyg@mail.ru

Doctor of Technical Sciences, professor

Russian Federation, 84, 20-letiya Oktyabrya Street, Voronezh, 394006

Vladimir A. Pendyurin

JSC RPE «Automated communication systems»

Email: pva777777@yandex.ru

general director

Russian Federation, 108, Peshe-Streletskaya Street, Voronezh, 394062

Dmitry K. Proskurin

Voronezh State Technical University

Email: pdk@vgasu.vrn.ru

Candidate of Physical and Mathematical Sciences, associate professor, rector

Russian Federation, 84, 20-letiya Oktyabrya Street, Voronezh, 394006

Kirill S. Safonov

Voronezh State Technical University

Author for correspondence.
Email: Safonov-kirik@mail.ru

junior researcher

Russian Federation, 84, 20-letiya Oktyabrya Street, Voronezh, 394006

References

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