RU2099832C1 - Double-input planar slot antenna - Google Patents

Abstract

FIELD: transceiving equipment for radio communication systems including satellite communications and television. SUBSTANCE: antenna built around two parallel metal plates has its upper plate incorporating two orthogonal, generally different sets of slot radiators and four horn-box (pill- box) feeds placed under lower plate of antenna that function to excite T-waves on four sides over antenna perimeter. Waveguide outputs of four feeds are paired by waveguide turnstile adder connected to external square waveguide which provides for isolation of antenna polarizations. When orthogonal sets of feeds are identical and aperture is square, antenna with be capable of receiving signals of four types of polarization (linear and circular) simultaneously operating in conjunction with additional external adders and amplifiers. When antenna operates at different frequencies in reception and transmission, signals are transmitted and received at different polarizations of antenna. Rectangular matching bosses are introduced in pill-boxes and three-step pyramids, in turnstile. Double-ended feed of antenna for each polarization at 600 mm aperture increases its passband. Antenna is provided with dielectric slow-wave structure having ε=1.4-2.5 and paired nonresonant slots of different length (l/λ=0.3-0.8) spaced λ/4 apart. EFFECT: facilitated matching of antenna, reduced level of directivity-pattern side lobes, extended antenna, reduced level of directivity-pattern side lobes, extended antenna passband, improved utilization factor of antenna surface and its gain to noise temperature ratio. 6 dwg

Description

 The invention relates to antenna technology and can be used in transceiver radio communication systems for various purposes, including satellite television and communication.

 Antennas for satellite communications and television based on parabolic mirrors are known. Such antennas are bulky, have significant windage, accumulate snow in the mirror bowls, and violate the architectural appearance of the building. In some countries, the placement of mirror antennas in cities is prohibited.

 Flat antennas (PA) are less bulky, have a lower wind load, can be installed on the walls of buildings and fences of balconies, do not violate the architectural appearance of buildings. PA can be folded, which is convenient for transportation and design of suitcase (case) antennas.

 For satellite television, as a rule, PAs are developed with the reception of the same type of polarization: vertical (B), horizontal (G), left circular (LC), right circular (PC). Reception of signals of a different polarization in this case requires the installation of a second PA.

For communication systems, PAs must have two inputs and receive a signal with a frequency f ₁ in one linear polarization and emit a signal with a frequency f ₂ in another linear polarization (PA, two way). The difference between the frequencies f ₁ and f is 20-30%. Rays for both polarizations should coincide in direction, usually they are oriented normal to the PA opening.

Known multi-layer PA with two inputs (antennas BAS-50 manufactured in Germany) EP, designed to receive television signals of arbitrary polarization. In PA there are 6-7 metal printed layers separated by dielectric layers [1] Two layers contain binary strip dividers and strip emitters. The layers are rotated 90 ^° , and emitters with orthogonal polarization are in the area of the holes in other metal layers. The hole system forms emitting channels in the PA with orthogonal field polarizations. The disadvantages of printed PAs include significant losses in strip lines, which reduces the force G and the parameter G / T of the antenna, where T is the noise temperature. PA BAS-50 (the area of the emitting cloth 500x500 mm) has a G / t value of 11 dB / K, which is significantly lower than the G / T values of the order of 12-14 dB / K achieved for single-input PAs of the same area. Multilayer PAs have significant weight (6.5 kg for the BAS-50 antenna) and are of great cost.

 More promising for communication systems are PA based on plane multimode waveguides, for which higher G / T values can be obtained than for strip antennas of the same area.

 There is a known option of constructing a two-input PA based on a plane multimode waveguide filled with a dielectric (ε 1.56) with two systems of mutually perpendicular resonant rectangular slots on the upper metal plate of the waveguide and two horn-parabolic drivers of the saw-box type [2] Each horn is excited by a coaxial at the top of the speaker and connects the wide part with the opening of the antenna. The horns form the second floor of the PA. The specified patent can be considered as a prototype of the proposed technical solution.

(l длина волны, e диэлектрическая постоянная) в режиме стоячей волны, когда волновод замкнут на конце, приводит к большим значениям КСВ на входе Т-волновода, возможности снижения которого в прототипе не рассматриваются. Коаксиальные выходы в рупорнопараболических возбудителях существенно усложняют конструкцию ПА в том случае, когда число рупорно-параболических возбудителей будет увеличено (двухсторонняя запитка) для расширения рабочей полосы частот ПА и для приема телевизионных сигналов одновременно двух круговых поляризацией или двух линейных поляризаций, как это обычно реализуется в зеркальных антеннах, возбуждаемых рупором с круглым входным двухполяризационным волноводом и ферритовым коммутатором.The prototype, however, does not solve the most important tasks that make it possible to design PAs for satellite systems of the Ku range with a given area (0.2 m ² or more) required by the standards for the decrease in the level of side lobes during transmission F (θ) = 29 + G-251qθ for angles θ = 1-48 ^° and the required broadband of 4-8% when receiving and transmitting. The use of identical rectangular resonant slots does not allow creating a special amplitude distribution over the opening of the PA, which is necessary to obtain the required reduction of the side lobes during transmission. Unilateral feeding of the aperture with a mouthpiece with an aperture length of 0.6 m or more does not provide the required operating frequency band of 4-8%. Transverse rectangular resonant slots are highly emitting. Common-mode addition of reflections from such gaps located in a multimode waveguide with a step

(l wavelength, e dielectric constant) in the standing wave mode, when the waveguide is closed at the end, leads to large values of the SWR at the input of the T-waveguide, the possibility of reducing which is not considered in the prototype. Coaxial outputs in horn-parabolic pathogens significantly complicate the design of the PA in the case when the number of horn-parabolic pathogens is increased (two-way power supply) to expand the working frequency band of the PA and to receive television signals simultaneously with two circular polarization or two linear polarizations, as is usually realized in mirror antennas excited by a horn with a round input bipolarization waveguide and a ferrite switch.

 Thus, the prototype does not solve the following problems arising in the satellite communications satellite and television.

 There is no tool for the formation of a special amplitude distribution over the opening to obtain the side lobes required for the transfer of decay.

 The required PA broadband (4-8%) is not realized with aperture lengths of 0.5-0.6 m in the Ku range, since one-way feeding is used.

 There is no tool to reduce the input SWR due to the common-mode addition of reflections from transverse rectangular resonant slots.

 There is no tool for receiving television signals of both two linear and two circular polarizations.

 The proposed design of the PA does not have the above-mentioned disadvantages of the prototype.

 The main structural elements of the proposed PA are shown in FIG. 1-4. In FIG. 1 shows a section through PA6 in FIG. 2 is a view of the PA from below, where 4 horn-parabolic pathogens and a turnstile waveguide adder are located, in FIG. 3 is a top view of the PA with the protective shield removed; FIG. 4 turnstile waveguide combiner.

In FIG. 1 designations are introduced: 1 the upper metal plate of a multimode T-waveguide containing two systems of orthogonal non-resonant rectangular slots (see Fig. 3); 2 a metal frame formed of four vertical partitions, each of which along the contour has the shape of a parabolic cylinder, fastened to each other, as well as to the upper and lower metal plates of a multimode T-waveguide and containing rectangular matching protrusions (see Fig. 1 and 2 ); 3 lower metal plate of a multimode T-waveguide, in which four slots are cut along the contour of the parabola, the width of which is equal to the height of the multimode T-waveguide (see Figs. 1 and 2); 4 four flat 90 waveguide N-horn, the base of which is the lower metal plate of a multimode T-waveguide, with four input rectangular waveguides and four outputs in the form of four slots located along the contour of the parabolas in the plate 3 (see Fig. 2); 5 turnstile waveguide combiner, which is attached to the bottom metal plate of a multimode T-waveguide, and connected to four input waveguides of flat 90-waveguide N-horns and having an external square output waveguide (see Fig. 1, 2 and 4); 6 cone coordinator of the turnstile waveguide combiner, which is attached to the lower metal plate of the multimode T-waveguide, 7- dielectric shield; 8 foam plate (ε = 1.1) for fixing the upper metal plate of a multimode T-waveguide; 9 dielectric plate filling a multimode T-waveguide; 10 metal gasket for mounting the upper metal plate of a multimode T-waveguide; 11 sealing; 12 a metal pin that connects the cone coordinator of the turnstile waveguide adder through a centering hole with the upper metal plate; 13 - corrugated antenna mount ring; 14 dielectric inserts for fixing the edges of the lower metal plate of the multimode T waveguide; 15 - switch; 16 converter for receiving television signals. Nodes 15 and 16 are produced by a number of companies and are used in mirrored television antennas. The output section of the square waveguide of the turnstile waveguide combiner is selected (16x16 mm) so that it is possible to connect purchased switches and converters with a standard input round waveguide with a diameter of 18 mm. FIG. 5 illustrates the circuit of the proposed input device, which allows to simultaneously receive all four polarizations of the received signal (V-vertical, H-horizontal, LC-left circular, RC-right circular). The circuit of Fig. 5 includes two additional (to the converter) low-noise amplifiers U ₁ and U ₂ , two output adders Σ ₂ , bridge device M. The function of the input adders Σ ₁ is performed by a waveguide turnstile adder (Fig. 4).

 On the upper metal plate of a multimode T-waveguide (Fig. 3), two systems of orthogonal non-resonant rectangular slots with orthogonal (along the X and Y coordinates) orientation of their axes are formed. Changing the length of the slots allows you to change the amplitude distribution of the stress intensity in the slots, which ensures the formation of a radiation pattern with the desired drop in the side lobes.

 In FIG. 3, the region on the upper metal plate of a multimode T waveguide with slots (AxA cross section) 1, circled by a square, is located above the layer of a slowing dielectric (ε = 1.4–2.5). Region 2 without gaps is the upper metal plate of the horn-parabolic pathogen.

, где λ₁ и λ₂ средние длины волн приема ( λ₁ порядка 26 мм) и передачи ( λ₂ порядка 21 мм). Расстояние между осями парных щелей

, что обеспечивает хорошее согласование такого парного изолированного излучателя (КСВ < 1,05) в линейке излучающего полотна (см. фиг. 6а) в режиме бегущей волны при произвольных значениях длин щелей l_i.In the case of receiving television signals in the web of FIG. 3, paired slots are used with the same pitch along the X and Y coordinates (d ₁ d ₂ ). To receive and transmit independently in two polarizations, step

where λ ₁ and λ _{2 are the} average wavelengths of reception (λ _{1 of the} order of 26 mm) and transmission (λ _{2 of the} order of 21 mm). The distance between the axes of the paired slots

that ensures good matching of such a paired isolated emitter (SWR <1.05) in the line of the radiating web (see Fig. 6a) in the traveling wave mode for arbitrary values of the slit lengths l _i .

In FIG. 6c presents a theoretical directivity pattern of an antenna line with parameters l _{2 of the} order of 21 mm, A 500 mm, d ₂ 17.7 mm, h 28, ε = 1.4, l _i 7.6 mm. A ruler of width d ₁ d ₂ (side walls in idle mode) was excited from two inputs. At the same time, a zero electric field (standing wave mode) appeared in the center of the ruler with a picofracture of about 14.0 for a terminal pair of slots. As you approach the inputs of the line, the SWR gradually decreases to values of about 1.5. The calculation of the diagram was carried out by the method of moments. From FIG. 6b it follows that for an antenna with identical paired emitters, the level of the side lobes significantly exceeds the values for the curve F (θ) = -29 + G-251qθ. (G 36 dB) For receiving television signals such a radiation pattern is quite satisfactory.

In FIG. 6c shows the directivity pattern of a ruler of the same length (A 500 mm, d ₂ 17.7 mm, h 28, e = 1.4) with paired slots l _{i of} different lengths. Values of lengths were taken; l ₁ l ₂ 7.2 mm, l ₃ l ₄ 7.4 mm, l ₅ l ₆ 7.5 mm, l ₇ l ₈ 7.6 mm, l ₉ l ₁₀ 7.7 mm, l ₁₁ l ₁₂ 7 , 8 mm. In the second half of the ruler, the lengths of paired slots decreased symmetrically in the reverse sequence. From FIG. 6c it follows that the level of the side lobes slightly exceeds the level of F (θ), mainly at large values of θ. The analysis showed that a further significant improvement in the radiation pattern is achieved by increasing the aperture of the antenna to A 600 mm and by decreasing the pitch d ₂ to 13.4 (d / λ ≅ 0.64), which is achieved using a dielectric moderator with a value of ε = 2 ,5. With increasing A / λ, all the nearest side lobes are compressed to the main maximum. The far side lobes (θ = 30–50 ^° ) decrease with decreasing d / λ. Both processes can be enhanced by introducing a steeper decrease in the radiation intensity through the slits in the initial and final parts of aperture A.

Claims (1)

A flat slot two-input antenna based on a multimode T waveguide formed by two parallel metal plates and filled with a dielectric, containing two systems of orthogonal rectangular slots on the upper plate and excited around the perimeter by horn-parabolic exciters, characterized in that the orthogonal rectangular slots are made non-resonant, and for excitation antenna uses four parabolic horn-pathogen containing respectively four planar waveguide 90 ^o H Rupo a, the base of which is the lower metal plate of the multimode T-waveguide, and four input rectangular waveguides, which are paired along the wide wall in the center of the antenna with a turnstile waveguide combiner with a cone matching, which is mounted on the lower metal plate of the multimode T-waveguide and through a centering hole with a pin on the upper metal plate of a multimode T-waveguide for its central fixation, the output square waveguide of the turnstile waveguide adder provides t independently receiving and transmitting antenna signals in two polarizations, the outputs of plane 90 ^o waveguide N-horns are closed by four metal partitions, together forming an antenna frame, fastened to the upper and lower metal plates of a multimode T-waveguide, the latter in the region of plane 90 ^o waveguide N -ruporov parabolas along the contour cut four slots, whose width is equal to the height of planar waveguide 90 ^o H-horn, on which a rectangular frame disposed through matching protrusions and are circumferentially couple ol produced bilateral T-excitation of the multimode waveguide at each of its polarization plane in-phase waves.

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