RU2325017C2 - Narrowband angled waveguide-to-radio adapter - Google Patents

Abstract

FIELD: microwave engineering.

SUBSTANCE: narrowband angled waveguide-to-radio adapter of length L contains short-circuit section of rectangle waveguide with T-shaped metal edge connected to coaxial line by inductive post. Inductive post is mounted at right angles to wide band of waveguide at distance 0.8677 L from short-circuit section of waveguide. Thus standing-wave ratio must not be below 1.2 within frequency range 2.44÷2.46 GHz.

EFFECT: provided specified standing-wave ratio.

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Description

The invention relates to microwave (microwave) devices for matching a coaxial transmission line and a rectangular waveguide with a T-rib at a frequency of 2.45 GHz.

Known designs of matching devices of different types of microwave transmission lines, one of which is a waveguide of complex cross section. So, to excite a dominant wave in a diplexer on a rectangular waveguide with a T-rib (PVTR), we used a direct junction of the basic structural element of a diplexer with a rectangular waveguide (PrV) [1]. Another design is a smooth (nonlinear) transition for matching PrV and PVTR [2]. In addition, the known designs of step quarter-wave transformers for matching PrV and N-waveguide [3].

The disadvantage of these transitional microwave elements is that they are designed to match simply connected waveguides of simple and complex cross-section. At the same time, in the microwave technology, it is often necessary to transfer electromagnetic energy from a multiply connected transmission line, for example, coaxial to simply connected, having a complex profile.

As a prototype of the invention, an angular coaxial waveguide transition (CVC) was chosen in which the inner conductor of the coaxial line is joined at an angle of 90 ° to the metal edge of the P-waveguide (PV) [4]. This broadband junction has a standing wave ratio of SWR <1.2 in 70% of the operating frequency band of the PV and is intended for use in communication technology. To ensure the alignment of the PV with the standard 50-ohm coaxial line in this transition, the following technical solutions were used:

- two-stage design of the coaxial pathogen;

- the axis of the inner conductor of the coaxial line is shifted relative to the axis of the outer conductor in the direction of the PV;

- between the pathogen and the rear wall of the transition, a short-circuited loop is switched on.

The disadvantage of the prototype is the complexity of its design, due to the requirements to ensure maximum broadband transition. In addition, the maximum dimensions of the capacitive gap formed by a metal edge and a wide PV wall are 11.7 × 9.7 mm for a frequency of 2.45 GHz [4], which limits the possibility of using the prototype in microwave heating systems on waveguides of complex sections, where the capacitive gap plays the role of a technological channel where the sample material is placed.

The objective of the invention is the creation of an angular coaxial waveguide transition of a simpler design, with a capacitive gap, the area of which exceeds the area of the capacitive gap of the prototype, providing an SWR of no worse than 1.2 near the operating frequency of 2.45 GHz.

The problem is achieved in that in a coaxial waveguide junction of the angular type, consisting of a short-circuited segment of a rectangular waveguide with a metal edge, connected using an inductive pin with a 50-ohm coaxial line, the T-shaped metal edge is joined to a piece of the coaxial line at right angles at a distance from the short-circuited end of the waveguide, equal to 0.8677L, where L is the transition length, and the transition design is single-stage, the external and internal conductors are coaxial the lines are aligned and the radii of the inner conductor of the coaxial line and the inductive pin are not equal to each other.

Distinctive features are significant, as they allow to achieve the task and get a technical effect. The design of the proposed transition is simpler than that of the prototype, since it uses a coaxial single-stage coaxial pathogen and there is no short-circuit loop. The size of the capacitive gap formed by a metal rib and one of the walls of the waveguide is approximately two times larger, and the overall dimensions are 1.3 times smaller than that of the prototype due to the T-shaped metal rib. The SWR values of no worse than 1.2 near the operating frequency of 2.45 GHz are ensured by placing the inductive pin at a distance of 0.8677L from the short-circuited end of the waveguide and choosing the radius of the inductive pin not equal to the radius of the inner conductor of the coaxial line.

The invention is illustrated by drawings. Figure 1 presents a three-dimensional configuration of a coaxial waveguide transition. Figure 2 shows the cross section of the transition in the XY plane at the junction of the inner conductor of the coaxial line, the inductive pin and the metal edge of the waveguide.

The inventive angular coaxial waveguide transition consists of a short-circuited segment of a rectangular waveguide 1 with a metal edge of a T-shaped 2 connected by an inductive pin 3 with a 50-ohm coaxial line having an inner conductor 4 whose radius is not equal to the radius of the inductive pin 3. Inner conductor 4 and the outer conductor 5 of the coaxial line have a coaxial spatial arrangement. The inductive pin 3 is placed at a distance of 0.8677L from the short-circuited end of the waveguide 1. The inductive pin 3 is placed parallel to the power lines at the maximum of the electric field of the dominant PVTR wave, which makes it possible, as in the prototype, to transform the TEM wave of the coaxial line into the main wave waveguide of complex shape.

Investigations of the electrodynamic characteristics of this transition, carried out using a three-dimensional numerical model using the finite element method, showed that the selected profile of the thermal expansion joint provides a lower wave impedance than the primary shock wave, and the design parameters are: q / L = 0.8677; r ₂ / r ₁ = 0.493; b / a = 0.5; L / a = 1.5; t / a = 0.4; d / b = 0.633, where a is the size of the wide wall of waveguide 1; b is the size of the narrow wall of the waveguide 1; t is the width of the metal ribs 2; d is the distance from the metal ribs 2 to the wide wall of the waveguide 1; L is the transition length 1; r ₁ is the radius of the inner conductor 4 of the coaxial line; r ₂ - the radius of the inductive pin 3 (figure 1, 2) provide an SWR <1.2 in a narrow frequency range of 2.44 ÷ 2.46 GHz. The angular-type coaxial-waveguide transition (Fig. 1) allows matching of the PVTR and standard 50-ohm coaxial transmission lines with dimensions: R = 3.5 mm, r ₁ = 1.52 mm (first option); R = 1.75 mm, r ₁ = 0.76 mm (second option), where R is the radius of the outer conductor 5 of the coaxial line. The overall dimensions of the waveguide assembly at a working frequency of 2.45 GHz are reduced by reducing the critical frequency of the dominant PVTR wave as compared to the PV [2]. At the same time, it ensures the best matching of two different types of transmission lines (PVTR and coaxial) in a narrow frequency range of 2.44 ÷ 2.46 GHz.

An example of a specific application of this transition is a laboratory analysis microwave chamber for scientific research of the processes of interaction of electromagnetic radiation with a frequency of 2.45 GHz with liquid substances, performed on a PCR, in which a dominant quasi-H ₁ wave is excited using an angular transition.

Literature

1. Labay V.A., Bornemann J. An integrated T-septum waveguide diplexer for compact front-end applications. // IEEE MTT Symposium Digest. 1993. P. 463-466.

2. Kolomeitsev V.A., Yakovlev V.V. Smooth transitions for matching a rectangular waveguide and a rectangular waveguide with a T-edge. // Radio engineering. 1991. No2. S.86-90.

3. Bornemann J., Arndt F. Modal-S-matrix design of optimum stepped ridged and finned waveguide transformers. // IEEE Trans. 1987. Vol. MTT-35. N6. P.561-567.

4. Waveguides of complex sections / G.F. Zargano, V.P. Lyapin, B.C. Mikhalevsky and others. - M .: Radio and communications, 1986. - 124 p.

Claims (1)

Angular-type coaxial waveguide transition, with an operating frequency of 2.45 GTZ, consisting of a short-circuited segment of a rectangular waveguide with a metal rib connected using an inductive pin with a 50-ohm coaxial line, characterized in that the T-shaped metal rib is connected to the segment the coaxial line at a right angle at a distance from the short-circuited end of the waveguide equal to 0.8677L, where L is the length of the coaxial waveguide transition, and the transition design is single-stage, external and internal The coaxial line conductors are aligned, and the radii of the coaxial line inner conductor and the inductive pin are not equal to each other.

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