RU2136090C1 - Aircraft antenna - Google Patents

Abstract

FIELD: antenna devices. SUBSTANCE: device has cylindrical resonator 1, which is open from one end and is equipped with flange 2, and filled with dielectric 3, coaxial connection 4 which is mounted on lower cover of cylindrical resonator 1 with sleeve 6 which serves as extension of outer housing of coaxial connection 4 inside cylindrical resonator 1, and central conductor 7 which is located inside this sleeve and serves as extension of central conductor of coaxial connection 4. Driver is designed as two halves of outer tube conductor 8, which are connected to one another and sleeve over coaxial connection 4 with space 9 (dotted line on drawing) in opposite to coaxial connection 4. In addition device has inner conductor 10 which is located inside one of two halves of outer tube conductor 8 and which one end is connected to inner conductor 7 of sleeve 6. In addition device has adapter which is designed as serial circuit of matching quarter-wave transformer 11, which is located inside outer tube conductor 8 in close proximity to space 9, and second end of inner conductor 10 and resistor 12, which is located in space 9 between two halves of outer tube conductor 8 and which second terminal is connected to opposite end of second half of outer tube conductor 8 in space 9, and U-shaped stub 13, which is connected in parallel to resistor 12 to its terminals. EFFECT: increased efficiency of antenna operations during and after heating conditions, loss and burning of heat-protection radio wave transparent antenna cover and heat- protection cover on aircraft side surface which encloses it. 3 dwg

Description

 The invention relates to the field of radio engineering, and more specifically to the field of antennas of aircraft (LA). It can be used as a transmitting or receiving antenna of an aircraft experiencing significant heat loads on the flight path.

 A slotted ring antenna is known [1, p. 531, FIG. 21. 21], containing a cylindrical resonator (CR), an annular gap in the upper cover of the CR, an exciter with a loop, an adjustment element in the form of a capacitor included in the excitation loop, and a coaxial connector located on the bottom of the resonator.

 Ring slot antenna works as follows. The high-frequency voltage from the microwave generator through a coaxial connector is supplied to the pathogen, which excites the ring slit of the resonator in-phase field. An annular gap emits an electromagnetic field into free space and forms a funnel-shaped radiation pattern (LH) with no radiation along the CR axis. Tuning the antenna and tuning it in frequency is done using the tuning element.

 When installing the antenna on an aircraft, the surface of the radiating slit is flush with the outer metal surface of the aircraft, a heat-shielding radiolucent antenna insert (TRAV) is installed above the CR opening, the entire remaining side surface of the aircraft is covered with a standard heat-protective coating (TZP).

 The disadvantage of the analogue is a sharp drop in antenna efficiency by 20 - 25 dB (100 times or more) relative to the initial value of the efficiency when the antenna is operating on an aircraft under conditions of heat loading and after heat loading, entrainment and burning of the grass and the surrounding TPS along the flight path of the aircraft. This is due to the fact that on the flight path of the aircraft under conditions of heat loading and related ablation and burning of the surface material of the AL on the outer surface of the GRA and TZP, a conductive dielectric layer of TRAV and TZP is formed, which shields, redistributes and partially absorbs the near fields of the antennas.

Known ring slot antenna [2], selected as a prototype, containing a CR, a coaxial connector mounted on the bottom cover of the CR along its axis, a pathogen in the cavity of the CR located in the center of the CR and connected to the inner conductor of the coaxial connector, an annular gap of width 0, 2 α where α _o is the average wavelength of the operating range located at the upper section of the CR near its side walls and formed by the pathogen and side walls and conducting a jumper in the cavity of the CR located parallel to the lower cover of the CR, at Volume one end of the jumper is connected to the pathogen, the other to the side wall of the CR.

 Ring slot antenna works as follows. The high-frequency voltage from the microwave generator through the coaxial connector is supplied to the pathogen. With the help of a pathogen, an annular gap is excited by a common-mode electromagnetic field, which radiates this field into free space, forming a funnel-shaped MD with no radiation along the CR axis and antenna. The conductive jumper in the cavity of the CR leads to the appearance of radial conduction currents in it, which do not change the field distribution in the annular gap, but increase the level of radiation along the axis of the antenna and thereby equalize the beams in this direction.

 The installation of the prototype on the aircraft is the same as the installation of the analogue, flush with the side metal surface of the aircraft, the antenna opening is closed by the GRAV, the remaining side surface of the aircraft is closed by the standard TZP.

 A significant disadvantage of reducing the efficiency of an aircraft’s antenna under conditions of heat loads on the flight path of the aircraft dramatically reduces the energy potential of the radio communication channels with the aircraft (by 20 - 25 dB).

 The problem to which the invention is directed, is to increase the efficiency of the aircraft antenna under the influence of heat loads and after heat loads, entrainment and burning of TRAV and TZP aircraft on the flight path.

 The technical result of the proposed solution is to increase the efficiency of the aircraft’s antenna under the influence of heat loads and after heat loads, entrainment and burning of the grass and surrounding TZP due to the concentration of the near field of the antenna above the CR opening.

b_п = (0,2λ_o-2l_n)sinα,

0,2Z_о ≤ R ≤ 0,25Z_o;

где λ_o - заданная длина рабочей волны, м;
R_вх и X_вх - заданная активная и реактивная составляющие входного сопротивления антенны в зазоре между двумя половинами внешнего трубчатого проводника в отсутствии согласующего устройства, Ом;
Z_оф - заданное волновое сопротивление фидера питания антенны, Ом;
Z_{о шл} - заданное волновое сопротивление шлейфа, Ом.This technical result is achieved in that in the antenna of the aircraft containing a cylindrical resonator open at one end, a coaxial connector located on the bottom cover of the cylindrical resonator, a pathogen and matching device located in the cavity of the same resonator, it is new that the coaxial connector is placed on a circle of diameter D _k, coaxial with the cylindrical cavity, the agent is in the form of two halves of the outer tubular conductor interconnected over coax cial connector having a gap with a gap of diametrically opposed coaxial connector and symmetrical with respect to a line connecting the coaxial connector centers and the gap between the two halves of the outer tubular conductor and being the diameter D _{to the} circumference and the inner conductor disposed within the first halves of the outer tubular conductor, each of half of the outer tubular conductor is made in the form of two arcs of a ring of length l _d each, starting from the gap and from the coaxial connector, co respectively, located around a circle of diameter D _k symmetrically with respect to diameter D _k , perpendicular to the diameter connecting the centers of the coaxial connector and the gap, a U-shaped segment with a jumper lying on a circle of diameter D _k . symmetrically relative to the same diameter as the arc of the ring, and the sides of length l _p parallel to the same diameter, and two straight segments connecting the second ends of the arcs of the ring with the ends of the sides of the U-shaped segment and forming an angle α with these sides, elongated inside the cylindrical resonator, the central conductor of the coaxial connector is connected to the first end of the inner conductor of the pathogen, the outer tubular conductor is connected to the upper end of the sleeve inserted into the cylindrical resonator, closed captive on the lower cover of a cylindrical cavity coaxial with the coaxial connector, a matching device configured as a series connected matching quarter wave transformer with characteristic impedance Z _o, disposed within the outer tubular conductor near the gap and connected with the second end of the inner conductor of the pathogen, and a resistor R, located in the gap between two halves of the outer tubular conductor, and loop U-shaped length l _mL connected parallel to resist in his conclusions and situated in the plane of the two halves of the outer tubular conductor, the second terminal of the resistor R is connected to the opposite end of the second half of the external tubular conductor in the gap, wherein the diameter D _{to the} circumference of the ring, the angle α between the sides of the U-shaped segments and straight segments length l _n sides of U-shaped segments and their width b _n, length l _d of each of the arcs of the ring, the values of the quarter wave impedance Z _o of the matching transformer and a resistor R, and the loop length l _SHL selected from leduyuschih relations
0.2λ _o ≤ D _to ≤ 0.25λ _o ,
27 ^o ≤ α ≤ 33 ^o ,

b _p = (0.2λ _o -2l _n ) sinα,

0.2Z _o ≤ R ≤ 0.25Z _o ;

where λ _o - a given length of the working wave, m;
R _I and X _I - the specified active and reactive components of the input resistance of the antenna in the gap between the two halves of the outer tubular conductor in the absence of a matching device, Ohm;
Z _of - the specified wave impedance of the antenna feed feeder, Ohm;
Z _{about SHL} - the given wave impedance of the loop, Ohm.

 The set of essential features of the proposed technical solution allows to increase the antenna efficiency by 10 - 15 dB (10 or more times) compared with the prototype when it is operated on an aircraft under the conditions of heat loads and after heat loads, entrainment and burning of grass and the surrounding cargo area along the flight path LA

 In FIG. 1 shows a sketch of the proposed antenna, in FIG. 2 is a sketch of the antenna driver, in FIG. 3 is a sketch of the installation of the antenna on the side surface of the aircraft.

 The antenna of the aircraft (Fig. 1) contains open at one end of CR1 with a flange 2, partially filled with a dielectric 3, a coaxial connector (KS) 4, mounted on the bottom cover 5 of CR1, with a sleeve 6, which is a continuation of the external housing KS4 inside the cavity CR1, and the central conductor 7 inside this sleeve, which is a continuation of the central conductor KC4, the pathogen, made in the form of two halves 8 of the outer tubular conductor, connected to each other and the sleeve 6 above KS4 and having a gap 9 (circled by a dashed line) diametrically opposite to KS4, an inner conductor 10 located inside one of the halves of the outer tubular conductor 8 and connected at one end to the inner conductor 7 of the sleeve 6, and a matching device consisting of serially connected matching quarter-wave transformer 11 located inside the outer tubular conductor 8 near the gap 9 and connected to the second the end of the inner conductor 10, and the resistor 12 located in the gap 9 between the two halves of the outer tubular conductor 8 and connected to the second terminal with an opposite nym end of the second half of the tubular outer conductor 8 in the gap 9 and the stub 13 U-shaped, connected in parallel to resistor 12 to its conclusion.

A sketch of the antenna driver is shown in FIG. 2. The causative agent, which is a single-turn loop antenna of reduced dimensions, contains two halves of the outer tubular conductors 14 and 15, interconnected above KC4 with a center at point A, having a gap 16 diametrically opposite KC4 with a center at point B and located symmetrically relative to the line, connecting the centers A and B and being the diameter D _{to the} circumference of the ring, and a conductor 17 placed in one of the halves of the tubular conductor. Each of the halves 14 and 15 of the tubular conductors contains two arcs 18 and 19 of a ring with a diameter of D _k and a length of l _d each, starting from point A and the gap 16, respectively, located around the circumference D _k symmetrically with respect to the diameter D _k perpendicular to the diameter connecting the centers A and B, U-shaped segment with a bridge 20, lying on a diameter D circle _to symmetrical relative to the same diameter as the arc 18 and 19, and two lateral sides 21 and 22, and two line segments 23 and 24 connecting the second ends of the arcs 18 and 19 with the ends of the sides 21 and 22 P -shaped segment and forming an angle α with these sides.

 A sketch of the installation of the antenna on the side surface of the aircraft is shown in Fig.3. TsR25 with flanges 26 is mounted flush with the side surface of the LA27 case using screws 28. The antenna aperture is closed from the outside by a heat-shielding radiolucent antenna insert 29, the rest of the side surface of the aircraft is closed by a standard TZP 30.

The antenna on the aircraft in the initial state works as follows. The high-frequency (HF) signal from the radio transmitter through KC4, the inner conductor 10, and the matching transformer 11 are led to the gap — the antenna supply point B, the connection point of the matching transformer 11 and resistor 12. The halves of the outer tubular conductors 14 and 15 are a short-circuited long line with a point short circuit (SC) at point A above KC4, in which both halves 14 and 15 of the outer tubular conductor are connected to the sleeve 6, made in the form of a frame antenna. A cosine distribution of the current of the RF signal with antinodes at points A and B and nodes at the midpoints of jumpers 20 is established along the perimeter of the pathogen, approximately equal to the wavelength λ _o , and the RF current flowing along the pathogen excites the opening (open end) of CP1 with orientation polarization (vector E) of the electromagnetic field (EMF) along the diameter connecting the midpoints of the jumpers 20, i.e., a linear polarization field. Opening CR1 emits an EMF of this linear polarization through GRAV 29 into free space. The maximum radiation is directed along the axis of CR1 (antenna).

A characteristic feature of the pathogen as a loop antenna is that the near field of the antenna with the field maximum E _max along the axis of the antenna is almost entirely concentrated over the opening TsR1 in the installation area of the GRAV 29 on the aircraft body. To the edges of the aperture CR1, and therefore, to the edges of the GRASS 29 EMF E drops to a value of E ≤ 0.15 E _max . Therefore, almost all the power of the RF signal supplied to the antenna is radiated by it into the free space through the GRAV 29.

During heat loads and after heat loads, entrainment and burning of the TRAV 29 material and the surrounding TZP 30 along the flight path of the aircraft, the antenna operates as follows. Under the influence of heat loads on the surface of GRAV 29 and TZP 30, a conductive coke layer is formed with a conductivity σ ≤ 0.5 S / m on the surface of TRAV and σ _o ≤ 50 S / m on the surface of TZP. Since in the initial state only 15% of the near field is located under the SCL, outside the GRA surface, the same ratio in the distribution of the near field remains after the formation of a conductive layer on the surfaces of the GRA and TSC. The main near-field energy remaining above the opening TSR1 under the layer of GRAV 29 is emitted through the GRA into free space, partially absorbed in the surface conductive layer with a conductivity of σ _o- ≤ 0.5 S / m. The remaining small fraction of the near field (up to 15%) under the layer of regular TZP with a conducting surface layer (σ _o ≈ 50 S / m) is partially absorbed by this conducting layer and partially transformed into a surface wave propagating along the TZ around the aircraft. Thus, the standard TZP practically does not affect the antenna efficiency. The presence of a conductive layer of GRAV reduces the efficiency slightly, since the surface conductive layer of GRAV has a relatively low conductivity σ _o ≤ 0.5 S / m. Although the antenna efficiency decreases compared to the original one, it is significantly higher than the efficiency of other antennas (by 10 - 15 dB) having other near field distributions above the opening.

The choice of the size of the frame pathogen is as follows. Select the diameter D _{to the} circle on which the segments of the arcs 18 and 19 and the jumpers 20 lie, according to the formula (1), for example, D _k = 0.2λ _o . The shoulder length l _{s of the} pathogen is determined by the formula l _s = R _k = 0.5 D _k , for example l _s = 0.1λ _o . The diameter d of the outer tubular conductors 8 is selected from the ratio d ≤ l _s / 10, for example, d = 10 mm. According to the directories for the assortment of pipes, for example, GOST 8734-75, GOST 14162-79, TU14-3-972-80, etc., select the corresponding pipe, for example, Tr.10 x 1.5, TU14-3-972 -80 with an outer diameter of d = 10 mm and an inner diameter of d _ext = 7 mm. Choose the width B _{p of the} jumpers 20 according to the formula (4), the length l _{p of} their sides 21 and 22 according to the formula (3), the length of the arcs 18 and 19 according to the formula (5). Select the angle α according to the formula (2) and the lengths of the straight segments 23 and 24 in accordance with the selected angles and lengths l _p .

где Z_оф - заданное волновое сопротивление фидера питания антенны Ом; ε_r - заданная относительная диэлектрическая проницаемость диэлектрика, которым заполняется вместе с проводником 18 внутренняя полость проводника 8, d_вн - выбранный внутренний диаметр трубы. Например, положив Z_оф = 500 м и ε_r= 2,1 (диэлектрик - фторопласт ФТ-4), найдем

d_вн/d_пр = 3,25, d_пр = 7/3,25 ≈ 2,1 мм,
так как внутренний диаметр трубы d_вн = 7 мм.The diameter of the inner conductor 17 d _CR placed inside one of the halves of the outer tubular conductor 8 is selected from the ratio

where Z _of - the specified wave impedance of the antenna power feeder Ohm; ε _r - a given relative dielectric constant of the dielectric, which is filled with the conductor 18, the inner cavity of the conductor 8, d _VN - the selected inner diameter of the pipe. For example, setting Z _of = 500 m and ε _r = 2.1 (dielectric - fluoroplastic FT-4), we find

d _int / d _ol = 3.25, d _ol = 7 / 3.25 ≈ 2.1 mm,
since the inner diameter of the pipe d _VN = 7 mm

где d_вн - выбранный внутренний диаметр трубчатого проводника 8; ε_r - заданная относительная диэлектрическая проницаемость диэлектрика, заполняющего внутреннюю полость согласующего трансформатора. Например, пусть

d_вн = 7 мм, Z_оф = 500 м, R_вн = 200 м. Тогда

d_вн/d_тр = 2,13; d_тр = 7/2,13 = 3,29 ≈ 3,3 мм
Определяют величину резистора 12, например R = 0,25 Z_о = 8 Ом.Tuning the antenna in a given frequency band is as follows. Is measured antenna input impedance _Rin Z = R + jX _{Rin Rin} in the frequency band to the antenna at point B of FIG. 2 in the absence of a matching transformer by any known method, for example, according to the Tatarinov method [3, p. 100]. Determine the values of R _I and X _I at the operating frequency f _o corresponding to the operating wavelength λ _o = c / f _o C = 3 • 10 ⁸ m / s. Knowing Z _of and R _I , calculate the impedance Z _about matching quarter-wave transformer according to the formula (6). The diameter d _{tr of the} inner conductor of the matching transformer 11 is determined from the formula

where d _VN is the selected inner diameter of the tubular conductor 8; ε _r is the specified relative dielectric constant of the dielectric filling the internal cavity of the matching transformer. For example, let

d _vn = 7 mm, Z _of = 500 m, R _vn = 200 m. Then

d _vn / d _mp = 2.13; d _tr = 7 / 2,13 = 3,29 ≈ 3,3 mm
The value of the resistor 12 is determined, for example, R = 0.25 Z _o = 8 Ohms.

где ε_r - относительная диэлектрическая проницаемость диэлектрика, в котором расположен шлейф; b - расстояние между проводниками шлейфа, d - диаметр проводников шлейфа. Положив, например, b/d = 2, ε_r= 2,1, найдем Z_{о шл} = 58,9 ≈ 60 Ом. Обычно величина b и d выбирают из конструктивных соображений.Determine the length l _{SL of the} U-shaped loop according to the formula (8). Pre-set the wave impedance of the loop, guided by the ratio

where ε _r is the relative dielectric constant of the dielectric in which the loop is located; b is the distance between the loop conductors, d is the diameter of the loop conductors. Putting, for example, b / d = 2, ε _r = 2.1, we find Z _{о шл} = 58.9 ≈ 60 Ohms. Typically, the values of b and d are chosen from design considerations.

Корпус ЦР1 с фланцем 2, втулка 6 могут быть изготовлены из различных металлов, например, алюминия Д16, стали 12Х18Н10Т и т.п.; трубчатый проводник 8 - из трубок соответствующего диаметра, например, латунных, стальных с внутренним диаметром d_вн ≥ 4 мм.Putting, for example, the working wavelength λ _o = 200 mm and X _I = 600 m, we find from formula (8)

Case ЦР1 with flange 2, sleeve 6 can be made of various metals, for example, aluminum D16, steel 12X18H10T, etc .; tubular conductor 8 - from tubes of the corresponding diameter, for example, brass, steel with an inner diameter of d _int ≥ 4 mm.

 As the dielectric 3 can be used with any high-frequency dielectric, for example, FT-4. As KC4, industrial high-frequency connectors of the type SR50-150F, SR50-73F, etc. can be used. The inner conductors 7 of the sleeve 6 of the tubular conductors 8 and the matching transformer 11, the conductors of the U-shaped loop 13 can be made of brass, for example LSV 9.

To confirm the operability of the antenna and achieve the technical result, an antenna model was made at the enterprise for operation at a frequency f = 1 GHz (wavelength λ _o = 300 mm). The design dimensions of the antenna are selected as follows:
the inner diameter of the CR D _p = 80 mm = 0.27 λ _o ;
cavity height h _p = 80 mm = 0.08 λ _o ;
FT4 dielectric insert height h _d = 13 mm = 0.5 h _p ;
pathogen circle diameter: D _k = 60 mm = 0.2 λ _o ;
diameter of GRASS from the material RTP-200 with ε _r = 4,5;
D _grass = 100 mm = 0.34 λ _o ;
insert thickness h _vst. = 12 mm = 0.04 λ _o .

The characteristics of the fabricated antenna and prototype mockups were studied before and after exposure to heat fluxes g = 450 W / cm ² at a gas temperature T ≈ 3000K and a gas outflow velocity V = 2000 m / s; exposure time t = 10 s. Heat fluxes were subjected to heat-shielding radiolucent antenna inserts from RTP-200 and the standard TZP LA surrounding these inserts. The characteristics of matching and radiation of the proposed antenna and prototype according to the results of measurements before and after exposure to heat fluxes simulating heat fluxes on the flight path of the aircraft are shown in the table.

The table allows you to draw the following conclusions:
- after exposure to heat fluxes, a surface conductive layer is formed on the surface of the TRAV and TZP, which worsens the radiation characteristics of the antennas;
- the decrease in gain after exposure to heat fluxes amounted to 33.3 dB for the prototype, for the proposed antenna 7.6 dB;
- the efficiency of the antennas after exposure to heat fluxes was 0.25% for the prototype, 8.3% for the proposed antenna;
- the decrease in efficiency compared with the initial state amounted to 24.2 dB for the prototype, for the proposed antenna 8.9 dB;
- the gain in efficiency of the proposed antenna compared with the prototype is 15.3 dB (or 33.9 times).

Loss of efficiency at 9 dB in the proposed antenna due to:
- losses on the redistribution of the near field in the aperture of the antenna and TRAV ≈ 5 dB;
- absorption losses in the conductive surface layer of GRAV ≈ 3 dB;
- loss on antenna mismatch ≈ 1 dB.

 The above analysis and the results of experimental measurements of the table show that the proposed antenna meets the criteria of "novelty" and "inventive step", is a technical solution; technically implemented, allows to achieve a technical result of increasing efficiency and can be used as a transceiver antenna of the aircraft.

Sources of information
1. Ya.N. Feld, L.S. Beneson. Antenna-feeder devices, part II, edition of VVIA im. Zhukovsky N.V., 1959.

 2. V.I. Kachaev, S.A. Plotkin, V.G. Tsybaev. Ring slot antenna. AC N 1539877 from 06/08/87. H10013.10. Op. 1/30/90, Bull 4.

 3. A.Z. Fradan, E.V. Ryzhov. Measurement of AFU parameters. M., Communication, 1972.

 4. Handbook of electrical materials. Energy, 1974

Claims (1)

Aerial of the aircraft, containing a cylindrical resonator open at one end, a coaxial connector located on the bottom cover of the cylindrical resonator, a pathogen and matching device located in the cavity of the same resonator, characterized in that the coaxial connector is located on a circle of diameter D _k , coaxial with the cylindrical resonator, the pathogen is made in the form of two halves of the outer tubular conductor, interconnected above a coaxial connector, having a gap with a gap of etralno opposite coaxial connector and symmetrical with respect to a line connecting the coaxial connector centers and the gap between the two halves of the outer tubular conductor and being the diameter D _{to the} circumference and the inner conductor disposed within the first halves of the outer tubular conductor, each of the halves of the external tubular conductor is formed as a two arcs of a ring of length l _d each, starting from the gap and from the coaxial connector, respectively located around the circumference of the diameter D _to symmetrically with respect to the diameter D _to perpendicular to the diameter connecting the centers of the coaxial connector and the gap, a U-shaped segment with a jumper lying on the circumference of the diameter D _to symmetrically with respect to the same diameter as the arc of the ring, and lateral sides of length l _n parallel the same diameter, and two straight segments connecting the second ends of the arcs of the ring with the ends of the sides of the U-shaped segment and forming an angle α with these sides, the central conductor elongated inside the cylindrical resonator to axial connector connected to the first end of the inner conductor of the pathogen, the outer tubular conductor is connected to the upper end inserted into the cylindrical sleeve resonator fixed on the lower cover of a cylindrical cavity coaxial with the coaxial connector, a matching device configured as a series connected matching quarter wave transformer with characteristic impedance Z _0, located inside the outer tubular conductor near the gap and connected to the second end of the inner about the path of the pathogen, and the resistor R, located in the gap between the two halves of the outer tubular conductor, and a U-shaped loop of length l _w connected parallel to the resistor to its terminals and located in the plane of the two halves of the outer tubular conductor, the second terminal of the resistor R is connected to the opposite end of the second half of the outer tubular conductor in the gap, while the diameter D _{to the} circumference of the ring, the angle α between the sides of the U-shaped segments and rectilinear segments, the length l _{p of} the sides U-shaped segments and their width b _p , the length l _{d of} each of the arcs of the ring, the wave impedance of the quarter-wave matching transformer Z ₀ and the resistor R and the loop length l _w selected from the following relations
0.2λ ₀ ≤ Dc ≤ 0.25λ ₀ ,
27 ^o ≤ α ≤ 33 ^o ,

b _p = (0.2λ ₀ -2l _n ) sinα,

0.2Z ₀ ≤ R ≤ 0.25Z ₀ ,

where λ ₀ is the specified wavelength, m;
R _I and X _I - the specified active and reactive components of the input resistance of the antenna in the gap between the two halves of the outer tubular conductor in the absence of a matching device, Ohm;
Z _of - the specified wave impedance of the antenna feed feeder, Ohm;
Z _Oshl - the given wave impedance of the loop, Ohm.

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