RU2761101C1 - Ultra-broadband horn antenna - Google Patents

Abstract

FIELD: antennas.

SUBSTANCE: invention relates to the field of ultra-broadband horn antennas based on double-ridge (with an H-shaped section) waveguides. The technical result is achieved by the fact that the antenna containing: a pyramidal horn with an H-shaped section; a waveguide-to-coaxial adapter (WGCA) connected thereto, made of a segment of a waveguide with an H-shaped section and a coaxial connector, differs from the prototype by the fact that in the WGCA, outside of the inputs of short symmetrical ridges, the walls thereof are smoothly expanded in pairs on both sides, and an ultra-broadband balancing apparatus based on an irregular strip transmission line is introduced into this irregular waveguide chamber, wherein the strips and metallisation of the asymmetric input of the balancing apparatus are connected to the central conductor of the coaxial connector and to the body thereof connected with the back wall of the irregular waveguide chamber, and the symmetrical outputs of the balancing apparatus are connected to the inputs of short symmetrical ridges of the WGCA.

EFFECT: significant increase in the bandwidth of the horn antenna, improved matching in the ultra-broad frequency band.

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Description

The technical field to which the invention relates

The invention relates to the field of broadband and ultra-wideband horn antennas made on the basis of two-ridge (H-shaped section) rectangular or circular waveguides. State of the art

A pyramidal horn antenna of H-shaped cross section is known from the prior art, the article "Investigation of the radiating properties of a pyramidal horn antenna of H-shaped cross section" Varentsov [and others], f. "Antennas", issue 7 (158), 2010 [1]. The antenna contains a pyramidal horn of H-shaped cross section and a coaxial-waveguide junction connected to it, made of a segment of an H-shaped waveguide and a coaxial connector installed on its wide wall and transversely connected by a central conductor to the tide of the far ridge at a certain distance from the short-circuiting rear the walls of the said waveguide.

The disadvantages of the analogue are: insufficient broadband (in accordance with the text [1] (p. 36) "the resulting frequency band at SWR = 2.5 3.3-15.2 GHz"), insufficient matching ("SWR = 2.5" ), large unevenness of the frequency dependence of the antenna gain (in accordance with Fig. 12 [1] (p. 37) the measured unevenness is not less than 4 dB).

One of the reasons for insufficient broadband, insufficient matching of SWR (SWR - standing wave ratio) and large irregularity of the frequency dependence of the gain of the antenna in question, as well as a number of other similar domestic and foreign antennas, given in the book "Centimeter Wave Transmission Lines". Per. from English G.A. Remeza. - M .: Publishing house "Sov. Radio ", 1951, pp. 366-368 [2], according to the author, is that the symmetrical design of the pyramidal horn of the H-shaped section is excited by an asymmetric high-frequency (HF) current.

The second reason for insufficient broadband, insufficient matching (VSWR) and a large irregularity of the frequency dependence of the gain of the antenna under consideration, according to the author, is that the transverse excitation devices widely used in antennas are formed in the gap between the crests of the pyramidal horn two waves. In this case, the wave propagating to the rear short-circuiting wall of the waveguide, having reflected from it, is summed up with the main wave (propagating to the antenna opening) out of phase due to different frequency incursions of the phase of the operating signals.

Note. A complex and expensive, not always successful method of calculating and performing stepped rear short-circuiting bulk walls of waveguides and antenna reflectors is known, on the basis of which foreign broadband antennas HF-906 (company ROHDE & SCHWARZ GmbH & Co.KG) and GP2000-281 have been developed and manufactured for individual parts of the frequency range (made in Italy).

Also known from the prior art is an ultra-wideband horn ridge antenna (Ultra-wideband horn ridge antenna with partial dielectric filling / K.I. Kisilenko, E.P. Timofeev, J. "Antenna", issue 7 (239), 2017 [3]). The antenna contains: a single metal horn with two identical (symmetrical) metal ridges and a coaxial connector installed at its narrow end; two dielectric lenses; two absorbers of higher types of waves and a matching device, made on a double-sided printed circuit board, connected by metallization to the housing of the horn, and the input strip with the central conductor of the coaxial connector.

The disadvantages of this device include: insufficient broadband (this follows from the graph of the measured values of the antenna gain versus frequency, shown in Fig. 8 [2]); insufficient matching (in accordance with the graph of the measured values of the SWR, shown in Fig. 7.1 [2], even in a narrow frequency band from 2 to 8 GHz, the SWR is not less than 2.5); large irregularity of the antenna gain versus frequency graph (from the antenna gain versus frequency graph shown in Fig. 8 [2], it can be seen that even in a narrow frequency band from 2 to 8 GHz, the irregularity is not less than 5 dB).

One of the reasons for the insufficient broadband, insufficient matching and a large irregularity of the antenna gain versus frequency graph is, according to the author, the fact that the symmetrical design of a single H-shaped horn is excited by an asymmetric HF current. Note that in the materials of the article on the UWB horn antenna it is indicated that it (the antenna) is excited through an asymmetric matching device "on a double-sided printed circuit board (dielectric substrate with metallization)". It is not specifically stated how it is made and how it is connected to two symmetrical metal ridges of a single horn.

In the article “Broadband horn antenna ridge” / E.P. Timofeev [and others]. J. "Questions of radio electronics", series RLT, issue 1, 2013 [4] in the annotation it is indicated that "... a new, simpler, design of a matching transition based on a shielded asymmetric strip line is proposed. It is also shown that the expansion of the frequency range of the antenna is possible with effective selective suppression of higher types of waves, without a noticeable effect on the main wave. "

The second probable reason for insufficient broadband, insufficient matching (VSWR) and large irregularities in the antenna gain versus frequency graph is, in the author's opinion, that the printed circuit board of the applied matching device is placed in the narrow throat of a single antenna horn and is therefore strongly influenced by its closely located walls.

As a prototype, a pyramidal horn antenna with an H-shaped section, published in [1], was chosen, containing: a pyramidal horn of an H-shaped section, a coaxial-waveguide junction connected to it, made of a segment of an H-shaped waveguide and a coaxial connector installed on it wide wall and transversely connected to the tide of the distal ridge at a certain distance from the short-circuiting rear wall of the said waveguide.

Signs of the prototype, coinciding with the essential features of the claimed invention: pyramidal horn of H-shaped section; a coaxial-waveguide junction connected to it, made of a section of an H-shaped waveguide and a coaxial connector.

The disadvantages of the prototype are: insufficient broadband, insufficient matching, large irregularities in the graph of the dependence of the antenna gain on frequency. According to the author, one of the reasons for insufficient broadband, insufficient matching (VSWR) and large irregularities in the frequency dependence of the gain of the prototype antenna is that the symmetrical design of the pyramidal horn of the H-shaped section is excited by an asymmetric HF current.

The second reason for insufficient broadband, insufficient matching (SWR) and large irregularities in the frequency dependence of the gain of the prototype antenna is that the transverse excitation device used in it (pin or probe and longitudinal excitation devices are also known, which also have disadvantages), two waves are formed in the gap between the crests of the pyramidal horn. In this case, the wave propagating to the rear short-circuiting wall of the waveguide, having reflected from it, is summed up with the main wave (propagating to the antenna opening) out of phase due to different frequency incursions of the phase of the operating signals.

The technical result of the invention is a significant increase in the broadband of the horn antenna, improved matching (VSWR) in an ultra-wide frequency band and a decrease in the unevenness of the graph of the dependence of the gain on frequency. Disclosure of the essence of the invention

The objective of the invention is to create an ultra-wideband horn antenna, devoid of the disadvantages of analogs.

The problem is solved due to the fact that in the well-known pyramidal horn antenna containing a pyramidal horn of the H-shaped cross-section, a coaxial-waveguide junction connected to it, made of a section of an H-shaped waveguide and a coaxial connector, the following differences are provided: in the coaxial-waveguide junction , outside the inputs of short symmetric ridges, are smoothly expanded in pairs on both sides of its walls and, in the formed irregular waveguide chamber, an ultra-wideband balun is additionally introduced, made, for example, on the basis of an irregular strip transmission line. Moreover, the strips and metallization of the unbalanced input of the ultra-wideband balun are connected, respectively, to the central conductor of the coaxial connector and its body, also connected to the rear wall of the irregular waveguide chamber, and the symmetrical outputs of the ultra-wideband balun are connected to the inputs of the short symmetrical ridges of the coaxial-waveguide junction.

Essential features of the proposed ultra-wideband horn antenna: pyramidal horn of H-shaped section; a coaxial-waveguide junction connected to it, made of an H-shaped section of a waveguide and a coaxial connector, while, in a coaxial-waveguide junction outside the inputs of short symmetrical ridges, smoothly expanded in pairs on both sides of its walls; an ultra-wideband balun is additionally introduced into the formed irregular waveguide chamber, made, for example, on the basis of an irregular strip transmission line; moreover, the strips and metallization of the unbalanced input of the ultra-wideband balun are connected, respectively, to the central conductor of the coaxial connector and its body, which is also connected to the rear wall of the irregular waveguide chamber, and the symmetrical outputs of the ultra-wideband balun are connected to the inputs of the mentioned short symmetrical ridges of the coaxial-waveguide junction.

In the first (general) feature, it is shown that the pyramidal horn is made on the basis of an H-shaped waveguide. Between its two symmetrical ridges, a smoothly diverging, for example, exponentially emitting (receiving) slit line is formed, which is well matched with free space and effectively operates in an ultra-wide frequency range when the inputs of these ridges are excited by a symmetric HF current. In the second (general) feature, it is shown that the coaxial-waveguide junction (its output part) is also made on the basis of an H-shaped waveguide.

The distinguishing features show that short symmetric ridges are used in the coaxial-waveguide junction; how an irregular (i.e., with variable dimensions in sections along the length) waveguide chamber is formed (which is a back-connected additional horn of smaller dimensions, in which the sections of the irregular waveguide chamber smoothly increasing along the length contribute to better matching with the main pyramidal horn of the H-shaped section and significantly reduce the negative impact of the spaced and inclined in space of its walls on the device inserted inside); what is introduced into it and how is it (ultra-wideband balun) connected to the coaxial connector, the rear wall of the irregular waveguide chamber and the short symmetrical ridges of the coaxial-waveguide junction. The latter are necessary for galvanic connection of the symmetrical outputs of the ultra-wideband balun to them, as well as for connection (output ends) with the symmetrical ridges of the main pyramidal horn of the H-shaped section (using screw-on waveguide flanges located at the output of the coaxial-waveguide junction and at the input horn).

The technical result in the proposed ultra-wideband horn antenna is achieved due to the fact that in it a symmetric pyramidal horn of the H-shaped section, together with a short symmetric section of the H-shaped waveguide connected to it (included in the coaxial-waveguide junction), are excited by a symmetric HF current with with the help of an ultra-wideband balun device additionally introduced and placed inside the increased volume of the formed irregular waveguide chamber. The latter is made similar to the device "matching transformer (ST) for ring mixers", conventionally given in the book "Solid-state microwave devices in communication technology", L.G. Gassanov [and others], - M. "Radio and Communication", 1988, p. 121, paragraph. 3 [5]. Laboratory models of the matching transformer were made by the author on the basis of the available experience, the optimal dimensions were found, and research was carried out in the frequency range from 0.03 to 18 GHz. Similar laboratory prototypes of ST were widely used as ultra-wideband baluns in the studied prototypes of antennas in stripline and air-stripe designs. When using the above-mentioned ultra-wideband baluns (for exciting symmetrical ridges with a symmetric current), there are practically no HF waves reflected from the back short-circuiting walls of the coaxial-waveguide junctions, which improves the matching and broadband of the antenna.

Table 1 shows the causal relationship between the set of essential features of the claimed object and the achieved technical result.

The proposed invention makes it possible to manufacture ultra-wideband horn ridge antennas with good matching, small irregularities in the frequency dependence of the antenna gain for ultra-wideband communications, ultra-wideband radio devices and for ultra-wideband measuring installations. Brief Description of Drawings

The technical essence and principle of operation of the prototype and the claimed ultra-wideband horn antenna are illustrated by drawings and graphs, in which:

FIG. 1a Shows the proposed UWB horn antenna (left side view).

FIG. 1b depicts the proposed UWB horn antenna (right side view).

FIG. 2 The graphs of the measured matching values (SWR) and transmission coefficients (K _p ) in the operating frequency range of the proposed ultra-wideband horn antenna (its laboratory layout) are shown - shown in red and a close analogue of the prototype - shown in black.

Notes:

1. The laboratory model of the ultra-wideband horn antenna (made according to the proposed technical solution) has dimensions: in the horn opening - 172 × 172 mm; at the junction of the pyramidal horn with the coaxial-waveguide transition (in the throat) - 55 × 55 mm (with a ridge horn length of 340 mm); at the location of the rear short-circuit wall of the irregular waveguide chamber - 95 × 95 mm (with the length of the combined coaxial-waveguide junction - 130 mm). However, it performs well in the 1.31 to 18 GHz frequency band.

2. To obtain the operating frequency band of the proposed ultra-wideband horn antenna from 1 to 18 GHz, it is necessary to increase the length of the horn of the mentioned laboratory layout of the proposed ultra-wideband horn antenna until the dimensions of its aperture (172 × 1.31) × (172 × 1.31) mm are obtained. e. up to sizes (225 × 225 × 445) mm.

3. The aforementioned (in the text to figure 2) measured between the test and the "reference" antennas (separated by a certain distance from each other) transmission coefficient (Kp) is proportional to the antenna gain (G).

Implementation of the invention

The possibility of implementing the claimed invention is shown in the figures: FIG. 1a and FIG. 1b.

The proposed UWB horn antenna consists of:

1) pyramidal horn of H-shaped section; a coaxial-waveguide junction connected to it (with the help of waveguide flanges), made of a section of an H-shaped waveguide, outside the inputs of short symmetric ridges of which are smoothly expanded in pairs on both sides of its walls and an irregular waveguide chamber (increased volume) is formed;

2) an ultra-wideband balun additionally introduced and placed inside the said irregular waveguide chamber; coaxial connector;

3) pyramidal horn 1; symmetrical ridges 2 and 3; waveguide flanges 4 and 5; segments of short symmetric ridges 6 and 7 (included in the coaxial-waveguide transition); smoothly pairwise expanded walls of the coaxial-waveguide junction 8, 9 and 10, 11 (forming an irregular waveguide chamber of increased volume); printed ultra-wideband balun 12 with stripes 13-14 (left view) and 15-16 (right view); rear short-circuit wall 17 and coaxial connector 18.

The proposed ultra-wideband horn antenna operates as follows.

When a microwave signal power is applied to the input coaxial connector (the permissible input signal power is several W when using a printed ultra-wideband balun in the proposed antenna and about 100 W when using an ultra-wideband air-strip balun), it (power) propagates through the ultra-wideband balun connected to it. the device, reaches the inputs of the balanced combs and excites them with a balanced RF current. Further, the microwave power through the radiating diverging slit formed between the symmetrical crests of the pyramidal horn of the H-shaped section spreads to the opening of the latter and “comfortably” (since the wave resistance of the slit in the opening of the pyramidal horn is practically equal to the wave impedance of free space) is radiated into free space.

In the process of tuning (checking) the proposed ultra-wideband horn antenna, it is checked for compliance with the drawing, the quality of its assembly, the absence of deformations (dents) on its body are checked, and its matching (i.e., the SWR value), the directional pattern and the values of the antenna gains are measured in the band of operating frequencies (to the graph of the frequency dependence of the antenna gain).

The above-described ultra-wideband horn antenna is used as follows: prepare the proposed ultra-wideband horn antenna for operation, for which to remove it from the standard package, remove the protective cap from its coaxial connector and install it at the appropriate workplace. Then connect the corresponding cable from the output of the transmitter power amplifier (or from the input of the receiving device) to its coaxial connector and start working.

Literature:

1. Varentsov E.L., Danilov A.A., Illarionov I.A., Kashin A.V. Investigation of the radiating properties of a pyramidal H-shaped horn antenna / Antenna. 2010. Issue 7 (158). S. 33-37.

2. Lines of transmission of centimeter waves. Per. from English G.A. Remeza. Moscow: Publishing house "Sov. Radio". 1951.

3. Kisilenko K.I., Timofeev E.P. UWB Partially Filled Horn Ridge Antenna / Antennas. 2017. Issue 7 (239). S. 56-61.

4. E.P. Timofeev [and others]. Broadband horn ridge antenna / Questions of radio electronics. 2013. RLT series. Issue 1.

5. Gasanov L.G. [and etc.]. Solid-state microwave devices in communication technology / Moscow, "Radio and communication". 1988.

6. Timofeev E.P. [and others] Broadband horn ridge antenna / Questions of radio electronics, RLT series, 2013

Claims (1)

An ultra-wideband horn antenna comprising: a pyramidal H-shaped horn; a coaxial-waveguide junction connected to it, made of a section of an H-shaped waveguide section and a coaxial connector, characterized in that in the coaxial-waveguide junction outside the inputs of short symmetric ridges, smoothly in pairs expanded from both sides of its walls and into the formed irregular waveguide chamber additionally an ultra-wideband balun is introduced, made on the basis of an irregular strip transmission line, while the strips and metallization of the unbalanced input of the ultra-wideband balun are connected, respectively, to the central conductor of the coaxial connector and its body, also connected to the rear wall of the irregular waveguide chamber, and the symmetrical outputs of the ultra-wideband balun are connected to the inputs of the short symmetrical crests of the coaxial-waveguide junction.

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