WO2019155101A1

WO2019155101A1 - Microwave-crossing device

Info

Publication number: WO2019155101A1
Application number: PCT/ES2019/070019
Authority: WO
Inventors: Mariano Baquero Escudero; Vicente Enrique BORIA ESBERT; Marco Guglielmi; Daniel Sánchez Escuderos
Original assignee: Universitat Politècnica De València
Priority date: 2018-02-07
Filing date: 2019-01-15
Publication date: 2019-08-15
Also published as: ES2672338B2; ES2672338A1

Abstract

This document describes a microwave-crossing device, which allows two microwave signals to cross relative to one another without any ideal or theoretical exchange of power or cross-coupling. The device that is the subject matter of the invention described in this document has at least two possible embodiments based on the same inventive concept: one of them has four ports with inlets and outlets in a rectangular guide that allows the crossing of two microwave signals with minimal interference; while the other has four ports with inlets and outlets in a double-ridge waveguide, which allows the crossing of two microwave signals (channels) with minimal interference.

Description

MICROWAVE CROSSING DEVICE

DESCRIPTION

OBJECT OF THE INVENTION

The object of the invention is framed in the technical field of telecommunications.

More specifically, the object of the invention is directed to its use as an element of a compact beam forming network, which facilitates the crossing of some channels with others along the distribution network. In fact, the object of the invention described herein has special utility in applications related to telecommunications satellites employing multi-beam antennas; whose radiating elements are interspersed and require power networks with microwave crossing devices.

BACKGROUND OF THE INVENTION

A microwave crossover device is a special type of device that allows two microwave signals to be crossed in a relative way without (ideally) a power exchange (without cross-coupling or cross-coupling). This type of device is necessary when very compact microwave components are designed, where space is limited, and where structures are forced by location restrictions.

This configuration allows a considerable increase in the capacity of the system with respect to the contoured coverage, implementing a frequency reuse scheme in different specific beams. Such operation requires the radiation of multiple independent beams that must be generated in the focal plane of the satellite reflector. In order to generate all these beams, advanced and compact beam formation networks must be implemented, so that all power antennas are fed correctly with a compact and low weight structure.

A beam shaping network can be defined in general as a network capable of generating the radio frequency (RF) amplitude and phase distribution necessary for the excitation of each element in a cluster of antennas. For example, the Antenna clustering can be powered by a Butler matrix, in which microwave crossing devices are key elements so that all radiating elements are in the same physical plane. In this application, the antenna beam is directed in a specific direction of space depending on the input port.

In the technical literature of planar circuits you can find many solutions for crossover devices. The most common strategy in planar circuits is based on the use of some type of ring-shaped circuit (see for example references in documents such as:

• "A novel compact planar crossover with simple design procedure", Liu Xin, Yu Cuiping, Liu Yuanan, Li Shulan, Wu Fan, Su Ming, Proceedings of 2010 Asia- Pacific Microwave Conference, pp. 1633-1636

• "Development Of Finite Ground Coplanar (FGC) Waveguide 90 Degree Crossover Junctions With Low Coupling", George E. Ponchak, Emmanouil Tentzeris, 2000 IEEE MTT-S Digest, pp. 1891-1894.

• Ά planar balanced crossover ", Yi-Hsin Pang, Everett D. Lin, Yen-Yin Chen, IEEE Transactions on Microwave Theory And Techniques, vol. 64, no. 6, pp. 1812-1821, June 2016.

• "Compact single- / dual-band planar crossovers based on strong coupled lines", Wenjie Feng, Tianyu Zhang, Wenquan Che, Quan Xue, IEEE Transactions on Components, Packaging and Manufacturing Technology, vol. 6, no. 6, pp. 854-863, June 2016.

Most planar crossovers, however, have a narrow operating band, and also have high insertion losses. This makes them unsuitable in practice for space applications (Ku band and above). On the other hand, the waveguide technology, which is the one chosen for the invention described in this document, exhibits good performance in high power and, therefore, is the most widely used option for satellite output networks. communications

An intermediate alternative that combines the advantages of planar technology with waveguide technology is substrate integrated waveguide (SIW) technology. A limited number of contributions with crossovers in SIW technology can be found in the technical literature, as follows from:

• "Ultra-compact millimeter-wave substrate integrated waveguide crossover structure utilizing simultaneous electric and magnetic coupling ", Ajay Babu Guntupalli, Tarek Djerafi, Ke Wu, 2012 MTT-S Digest, 2012, pp. 1-3.

• “60 GHz substrate integrated waveguide crossover structure", Tarek Djerafi, Ke

Wu, Proceedings of the 39th European Microwave Conference, pp. 1014-1017, 2009.

and all of them use pairs of directional couplers.

In "Low loss waveguide four-port crossover Circuit and its feed application for cross-slot antenna", K. Chang, M. Li, K. A. Hummer, R. A. Speciale, Electronics Letters, vol. 27, no. 1 1, pp. 997-998, 5/23/1991 a waveguide crossover is proposed based on a circular waveguide, which deals only with the feeding of a single radiating transverse groove element.

To this day, microwave filters are known that produce a waveguide crossing in this direction. The contents of EP0315064 A2 are known, which refers to a crossover for the construction of a Butler matrix comprising a rectangular waveguide structure divided by a wall that extends along the central axis and divides it into two rectangular and coplanar waveguides; where the central wall has two length openings half the wavelength of the guide and approximately half the wavelength of the guide separated. Said device also has impedance coupling structures located on the side walls in positions facing the openings of the central wall, that is, it is composed of two couplers each introducing a 90 ^e offset. Under these conditions a crossover is produced from a waveguide to the adjacent one.

Document US5274839 A discloses a 0-dB coupler obtained by means of a pair of parallel rectangular waveguide channels whose terminations define two input ports and two output ports. Between both channels, five wavelength guide branches extend a quarter of the wavelength of the guide (figures 5, 6; and 1 1; column 8, lines 9-68).

The document "Generalized Multiport Waveguide Switches Based on Multiple Short-Circuit Loads in Power-Divider Junctions" by Ruiz-Cruz et al. It features multiport waveguide switches based on short-circuit loads integrated into rectangular cross-wave type waveguides. Switching is achieved with loads of Short circuit and open circuit along the guide in rectangular waveguides ridge. A complete class of SP4T based on this concept is presented, and in particular the type T that requires the realization of a crossover is manufactured and tested for Ku band, with insulation greater than 30 dB and return losses of 23 dB.

DESCRIPTION OF THE INVENTION

The object of the invention is directed to a device that implements integrated microwave filter and crossover functions in rectangular waveguide and double-ridged guide (double-ridge for its Anglo-Saxon nomenclature commonly used in the technical field of the invention) .

The object of the invention allows exchanging the position of the output ports of the two filters in parallel with respect to the position of their input ports in the same volume occupied by the two filters; that is, without extending to the surrounding space, while the signals are filtered independently along the two channels. In this way, the most compact crossing device possible can be obtained, including the filtering functions.

For this, a device is proposed that combines the functions of microwave filter and signal crossing, as shown in Figure 1. The device consists of two filters that can comprise filtering structures and that we can name for example: "a" and "b" being divided into two parts (in Figure 1, elements 1 1 and 12 for the filter "a", and elements 21 and 22 for the filter "b") connected through a coupling element common to both filters such as a common cavity (striped box in Figure 1). The different parts of the filters are located in such a way that the common cavity implements a crossing of waveguides to guide the signal from part 1 -a (element 1 1 in figure 1) to part 1 -b (element 12 in Figure 1) of the first filter, and from part 2-a (element 21 in figure 1) to part 2-b (element 22 in figure 1) of the second filter, without coupling of energy from one filter to another. This document describes several implementations of the crossover function.

The device object of the invention has two possible alternative embodiments as a solution to the problem posed.

In a possible implementation of the object of the invention there is a device for Four-port microwave with inputs and outputs in rectangular guide that allows the crossing of two microwave signals with a minimum of interference. The device is designed in such a way that the two signal channels exhibit a microwave filter type behavior, where the center frequency, bandwidth and order of the filters can be designed and manufactured according to the system specifications in the that the device has to operate.

In an alternative implementation of the object of the invention there is a four-port microwave device with double-ridge waveguide inputs and outputs that allows the crossing of two microwave signals (channels) with a minimum of interference . The device is designed in such a way that the two signal channels exhibit a microwave filter type behavior, where the center frequency, bandwidth and order of the filters can be designed and manufactured according to the system specifications in the that the device has to operate.

DESCRIPTION OF THE DRAWINGS

To complement the description that is being made and in order to help a better understanding of the characteristics of the invention, according to a preferred example of practical implementation thereof, a set of drawings is attached as an integral part of said description. where, for illustrative and non-limiting purposes, the following has been represented:

Figure 1 .- Shows a schematic view of the object of the invention.

Figure 2.- Shows a perspective view of the device of the invention in its embodiment based on filters with rectangular ports operating at different frequencies; defining two cross filters in rectangular guide for different frequencies whose response can be seen in the graph included in this figure 2.

Figure 3.- Shows a perspective view of the device of the invention in its embodiment using two three-pole filters with inductive windows; defining two rectangular filters in a rectangular guide tuned to the same central frequency whose response can be seen in the graph included in this figure 3. Figure 4 Shows a perspective view of the device of the invention in its embodiment using double-ridge waveguide filters operating at different frequencies; defining two cross-filters in guide with double rods with different center frequencies whose response can be seen in the graph included in this figure 4.

Figure 5.- Shows a detail of the coupling element used in the double-ridge waveguide device of figure 4.

Figure 6.- Shows a perspective view of the device of the invention in its embodiment using double-ridge double-cross filters operating at the same center frequency, whose response can be seen in the graph included in this figure 6.

PREFERRED EMBODIMENT OF THE INVENTION

The invention described in this document can be used in telecommunications satellites that employ antennas of multiple spot beams; as a key element to implement the power networks of these antennas. Thus, it is necessary that a preferred embodiment of the object of the proposed invention, there is a device that combines the functions of microwave filter and signal crossing, is shown in Figure 1; where the structure based on two filters (1, 2) preferably based on rectangular guides, designed to operate preferably at two different center frequencies and preferably with the same bandwidth, with a shared central cross resonator acting as a cavity (3) ) center of the two filters (1, 2) as seen in figure 2 or figure 3.

In the implementation shown in Figure 2, the device is formed by a first filter (1) and a second filter (2), which respectively are divided into two parts giving rise to: a first part of the first filter (1 1) , a second part of the first filter (12), a first part of the second filter (21) and a second part of the second filter (22), connected through the common cavity (3), the first part of the first filter being preferably (1 1) and the second part of the first filter (12) arranged aligned and contiguous and the first part of the second filter (21) and the second part of the second filter (22) also arranged aligned and contiguous .. The parts (1 1 , 12,21, 22) of the filters (1, 2) are located in such a way that the common cavity (3) implements a waveguide crossing to guide the signal from the first part of the first filter (1 1) to the second part of the first filter (12), and from the first part of the second filter (21) to the second part of the second filter (22), without energy coupling between filters (1, 2).

In a preferred embodiment of the object of the invention, the device acts as a rectangular guide cross member whose filters (1, 2) are arranged orthogonally forming a cross. In this device (see figure 2) the filters in rectangular guide are configured to operate at two different central frequencies and with the same bandwidth, whose shared resonator (3) acts as the central cavity of the two filters (1, 2). If the central crossing is symmetrical, there is no coupling between the two filters (1, 2), and the signal can cross the path of the other filter without interference. Fig. 2 shows an example using a three-pole filter with inductive windows (4), although the filtering structures may be based on capacitive couplings or inductive couplings.

The structure shown in Figure 2 provides more than 25 dB of isolation between the two paths (channels) of the signal. In a possible alternative embodiment of the object of the invention, the order of filters (1, 2) is increased in order to obtain a higher level of insulation.

The embodiment shown in Figure 2 is based on two filters (1, 2) that preferably have the same bandwidth. However, in possible alternative embodiments of the object of the invention, filters (1, 2) with respective bandwidths may be different from each other.

The cross resonator shown in the structure of Figure 2 acts as the central resonator of the two filters. The same basic operation can be obtained if the resonator used as a crossover element is any other resonator of either of the two filters.

In a possible alternative embodiment of the object of the invention, shown in Figure 3, the device of the invention has the characteristic of implementing the crossing of the two microwave signals preferably at the same frequency. Figure 3 also shows a graph showing the response obtained.

In a still more alternative embodiment of the object of the invention, the device described here has to be cross-linked filters (1, 2) in double waveguide caballón (or double ridge) as seen in figures 4 to 6; functioning as a four-port microwave device with inputs and outputs in a double-wave (ridge) waveguide, which allows the crossing of two microwave signals (channels) with a minimum of interference.

In addition, the device object of the invention can be configured so that the two signal channels exhibit microwave filter type behavior, where the center frequency, bandwidth and order of the filters (1, 2) can be designed and manufacture according to the specifications of the system in which the device has to operate.

In the crossover devices shown in figures 4 and 6, a rectangular guide section (see details in figure 5) which is part of the central inverter (or coupling element) of both filters is used as the crossover element. The same basic operation can be obtained if the inverter used as a crossover element is any other inverter of either of the two filters (1, 2).

Claims

1. Microwave crossover device, characterized in that it comprises two crossed filters (1, 2) and which in turn comprise a series of filtering structures that intersect in a cavity (3) common to both filters (1, 2) that it is a resonator; where the first filter (1) comprises a first part of the first filter

(1 1) and a second part of the first filter (12), and the second filter (2) comprises a first part of the second filter (21) and a second part of the second filter (22), the cavity (3) being common located at a central crossing point between the filters (1, 2), said central crossing point being defined in a crossing zone between the filters (1, 2) defined between the first part of the first filter (1 1) and the second part of the first filter (12), such that the defined central crossing is symmetrical.

2. Microwave crossing device according to claim 1, characterized in that the filters (1, 2) are arranged orthogonally crossed forming a cross, the cavity (3) being located at its intersection.

3. Microwave crossing device according to claim 1, characterized in that the first part of the first filter (1 1) and the second part of the first filter

(12) are arranged aligned and contiguous.

4. Microwave crossing device according to any one of claims 1 to 3, characterized in that the filters (1, 2) are standard rectangular guide filters with resonators implemented by means of empty rectangular guide sections.

5. Microwave crossing device according to any one of claims 1 to 4, characterized in that the filtering structures are based on capacitive couplings or inductive couplings.

6. Microwave crossing device according to any one of claims 1 to 5, characterized in that the filters (1, 2) operate at the same frequency.

7. Microwave crossing device according to any one of claims 1 to 6, characterized in that the filters (1, 2) have different respective bandwidths.

8. Microwave crossing device, characterized in that it comprises two filters (1, 2) which in turn comprise a series of filtering structures that intersect in a coupling element common to both filters (1, 2); wherein the first filter (1) comprises a first part of the first filter (1 1) and a second part of the first filter (12), and the second filter (2) comprises a first part of the second filter (21) and a second part of the second filter (22).

9. Microwave crossing device according to claim 8, characterized in that the first part of the second filter (21) and the second part of the second filter (22) are arranged aligned and contiguous.

10. Microwave crossing device according to claim 8 or 9, characterized in that the filters (1, 2) are double-ridge waveguide filters where the resonators are implemented with double waveguide sections caballón (double-ridge).

eleven . Microwave crossing device according to any one of claims 8 to 10 characterized in that the filters (1, 2) are adapted to operate at the same frequency.

12. Microwave crossing device according to any one of claims 8 to 10 characterized in that the filters (1, 2) have different respective bandwidths.