WO2000077886A1

WO2000077886A1 - Antenna

Info

Publication number: WO2000077886A1
Application number: PCT/DE2000/001449
Authority: WO
Inventors: Thomas Von Kerssenbrock; Patric Heide
Original assignee: Siemens Aktiengesellschaft
Priority date: 1999-06-10
Filing date: 2000-05-09
Publication date: 2000-12-21

Abstract

The invention relates to an antenna, comprising a radiation element (1), which contains at least one substrate (11) and at least one planar resonator (12) that is applied to said substrate (11), and a planar waveguide (2). The inventive antenna is characterized in that the resonator (12) is separated from the waveguide (2) by a gap which lies parallel to a plane of the resonator (12).

Description

description

antenna

The invention relates to an antenna for high frequencies and a method for producing such an antenna.

In: J.-F. Zürcher, F.E. Gardiol, "Broadband Patch Antennas", Artech-House 1995, pages 3 to 47, describe various embodiments of patch antennas. Several forms of resonators (so-called "patches") and waveguides ("wave guides") are shown. The resonator is either applied to the same carrier as the waveguide or separated from it by means of a further layer.

In: 0. Zinke, H. Brunswig, "Hochfrequenztechnik 1", 5th edition Springer, pages 157 to 177, various waveguides or feed networks are described such as the microstrip line ("microstrip"), coplanar lines and the open slot line (" Slotline ").

From P. Petre et al., "Simulation and Performance of Passive Microwave and Millimeter Wave Coplanar Waveguide Circuit Devices with Flip Chip Packaging", Electrical Performance of Electronic Packaging, IEEE, New York, NY, 1997, Conference paper, San Jose, CA. , October 27-29, 1997 a coplanar wave guide ("Coplanar Wave Guide", CPW) is known which feeds microwaves or millimeter waves into a monolithic microwave circuit ("Monolithic Microwave Integrated Circuit", MMIC). The MMIC has been connected to the CPW using flip-chip technology.

In W. Heinrich et al., "Millimeter wave characteristics of flip-chip interconnects for multi-chip modules", multi-layer circuit units ("chips") are described, which are fed by means of a CPW. The flip-chip technology for contacting semiconductor chips is described, for example, in Hans-Jürgen Hacke: Montage Integrated Circuits, Springer Verlag, 1987, pages 108 to 118.

An object of the present invention is to provide an antenna with a high efficiency.

Another object of the present invention is to provide an antenna with a high bandwidth.

It is also an object of the present invention to provide an easily mountable antenna.

It is another object of the present invention to provide an antenna that is easy to manufacture.

The present invention should also be connectable to existing feed networks or waveguides.

The objects are achieved by an antenna according to claim 1 and a method for producing the same according to claim 8. Advantageous refinements can be found in the respective subclaims.

The antenna has a radiation element which contains at least one substrate and at least one planar resonator on each substrate. In the simplest case, this is a single resonator applied to a substrate. However, several resonators can also be applied to a substrate and / or several substrates can be used.

There is also a planar waveguide. By means of the waveguide, the antenna can, for. B. connected to a wave generator. Waves, in particular microwaves and millimeter waves, can be fed into the resonator via the waveguide. The resonator is separated from the waveguide by a gap. The gap is parallel to a plane of the resonator. This condition is e.g. B. given when the resonator and the waveguide are arranged in parallel one above the other.

Such an antenna has the advantage that the gap creates a region of low permittivity between the waveguide and the resonator. This in turn results in a high antenna efficiency, analogous to a low power loss, and a higher bandwidth.

This antenna is also easy to manufacture because the radiation element and the waveguide can be manufactured separately using flip-chip technology.

It is advantageous if the planar waveguide is a coplanar waveguide (CPW) because, among other things, it has a low line loss and a simple one

Has structure. A CPW has at least one center conductor (“CPW feed”) and one ground (“ground”), which are typically applied to one side of an electrically insulating substrate.

If the waveguide is a CPW, it is favorable that the central conductor is electrically connected to the resonator, advantageously in such a way that the feed impedance is optimal.

However, it can also be advantageous if the waveguide is a microstrip waveguide because it has a low insertion loss and is also widespread. In this case, a strip - typically a metallization - is positioned above a mass, typically separated by a substrate. It is advantageous if the substrate of the emitting element is electrically insulating and low-loss. To use the flip-chip method ("flip-chip bonding"), it is also favorable if this substrate withstands a temperature T 300 300 ° C. during thermocompression bonding without damage. Both advantages are obtained if the substrate is made from A1 ₂ 0, Si ₃ N ₄ , SiC, Si0 ₂ , Teflon or Duroid. The use of A1 ₂ 0 ₃ or glass is particularly preferred. Glass is a little less loss-free than A1 ₂ 0 ₃ , but easier to manufacture or to shape than a ceramic.

The same advantages also apply to a substrate of the waveguide.

It is also advantageous if the resonator consists of a highly conductive material. The use of a noble metal is particularly preferred due to the good corrosion resistance. The expert is familiar with, for. B. Au, Ag, Cu, Pt or an alloy containing these metals, e.g. B. AgAu or PtRd.

It is advantageous if the waveguide is connected to the radiating element by means of the flip-chip technology, because this enables simple manufacture of the individual parts and inexpensive assembly. The gap is also easy to manufacture. In addition, the height of the gap can be adjusted in a simple manner.

The gap is usually exposed to the environment so that it can fill with air. Due to its low permittivity, an air gap generates a low power loss. In addition to air or vacuum, the gap can also be filled with any other gases.

However, even after using the flip-chip technique, the gap can be made with a hardening liquid with the lowest possible permittivity and with the least possible loss be filled at high frequencies, e.g. B. with a resin or a foam. This has the advantage that the radiation element is better fixed and is protected against contamination. Favorably, the liquid is so thin during the filling of the gap that the gap can be filled evenly.

For simple, in particular manufacture, in particular by means of flip-chip technology, it is advantageous if the radiation element is fixed to the waveguide by means of a spacer in the form of a plurality of support bumps.

In addition, the resonator in the case of an electrical connection between the waveguide and the resonator by means of an RF bump with the wave feed, for. B. the center conductor of the CPW or the strip of the microstrip waveguide, the waveguide. However, field coupling (aperture coupling) is also possible

The height db of the bumps corresponds approximately to the height of the gap. It is particularly preferred if the height db of the bumps is between 40 μm and 100 μm, in particular between 50 μm and 70 μm (“microbumps”). However, the height can easily be up to 1000 μm.

In the following exemplary embodiments, the antenna is shown schematically in more detail.

FIG. 1 shows an antenna before assembly, FIG. 2 shows an antenna after assembly, FIG. 3 shows an antenna after assembly, FIGS. 4a to 4c show different possibilities for wave feeding (food network) according to Zürcher et al. 5 shows several embodiments of resonators according to Zürcher et al., FIGS. 6a to 6f show several embodiments of antennas with different connection types according to Zürcher et al. Figure 4a shows a sectional front view of a waveguide in the form of a microstrip waveguide according to J.-F. Zürcher et al. (see above), page 3.

A strip 15 ′ and a flat mass 15 are applied to opposite surfaces of a substrate 14. In the microstrip line, the field is guided between strips 15 'and ground area 15. The main part of the field is in the substrate, a smaller part in the air.

Figure 4b shows a sectional view m front view of a waveguide in the form of a slot guide ("Slotline wave guide") according to J.-F. Zürcher et al. (see above), page 3. On the same surface of the substrate 14, a left mass 16 'and a right mass 16 are applied. The field is guided between left mass 16 'and right mass 16.

FIG. 4c shows a sectional view in front view of a waveguide in the form of a coplanar waveguide, CPW according to J.-F. Zürcher et al. (see above), page 3. Here, a middle conductor 17 '("CPW feed") and two flat metal layers are applied as mass 17 on one side of the substrate 14. The field is guided between the center conductor 17 'and the two ground areas 17.

The planar lines have in common that they represent an inexpensive alternative to conventional waveguides, in particular waveguides. The parameters (stripe width, high and permittivity of the substrate etc.) determine the quality of the conductors (see also 0. Zinke et al.)

Figure 5 shows different types of planar resonators according to J.-F. Zürcher et al. (see above), page 20. The resonators 121 are in microstrip technology on the substrate 14. One recognizes the diverse planar antenna shapes, such as. B. square, triangular etc. Figure 6a shows an antenna with microstrip waveguide according to J.-F. Zürcher et al. (see above), page 27. Here, the strip 15 'is electrically connected to the resonator 121.

Figure 6b shows an antenna with microstrip waveguide according to J.-F. Zürcher et al. (see above), page 29.

The resonator 121 is fed by means of a field 15 applied to the same side of the substrate 14 by means of a strip 15 '. The strip 15 'is attached separately from the resonator 121.

Figure 6c shows an antenna with microstrip waveguide according to J.-F. Zürcher et al. (see above), page 30.

The strip 15 'is attached below the resonator 121 and separated from it by an additional insulating layer 14'. The resonator 121 is operated via the strip 15 'by means of field coupling.

FIG. 6d shows a further embodiment of an antenna in SSFIP ("strip slot foam inverted patch") design according to J.-F. Zürcher et al. (see above), page 47.

Here, the strip 15 'is separated from a layer provided with a slot by a substrate 14 and the layer is in turn separated from the resonator 121 by a layer 15' 'of hardened foam. The patch is glued directly onto the foam using a flexible film.

Figure 1 shows an oblique view of an antenna before its assembly using flip-chip technology.

A coplanar waveguide 2 (CPW) consists of a substrate 21 made of A1 ₂ 0 ₃ , which is coated with a central conductor 22 in the form of a metallic tongue. From this, electrically isolated, the mass 23 is applied to the substrate 21 in the form of a metallic layer. 3 support bumps 31 are applied to the mass 23 as spacers. On the wave ter is an electrically conductive HF (radio frequency) Bu p 4 attached.

There is also a radiation element 1, which consists of a substrate 11, a resonator 12 mounted thereon and four metallizations 13. The metallizations 13 are positioned so that they correspond to the distribution of the support bumps 31.

For assembly, the radiating element 1 is folded onto the waveguide 2 such that the metallizations 13 rest on the support bumps 31 and then the radiating element 1 and the waveguide 2 are pressed onto one another (indicated by the arrows).

This is done by means of thermocompression bonding at a temperature T between 250 ° C and 300 ° C. Because of its high temperature resistance, a substrate 13, 21 made of A1 ₂ 0 _{3 is} well suited for this.

Pressing creates a fixed connection between the radiating element 1 and the waveguide 2. The pressing process is controlled so that the resonator 12 is at a constant distance db from the waveguide 2. At the same time, the center conductor 22 is also connected to the resonator 12 by means of the HF bump 4 during pressing.

Figure 2 shows a sectional view in front view of the antenna of Figure 1 after assembly.

The substrate 21 of the waveguide 2 from A1 ₂ 0 ₃ has a thickness ds = 635 μm. In addition to A1 ₂ 0 ₃ , the use of other non-conductive materials is also possible, e.g. As SiC, Si ₃ N ₄ , Teflon or Duroid, which also have the advantage of withstanding the temperatures necessary for thermocompression bonding. The radiation element 1 also has an Al ₂ 0 ₃ substrate 13 with a thickness of dp = 127 μm.

Of course, the resonator 12 can also be connected to the waveguide by means of other flip-chip techniques, e.g. B. reflux bonding ("reflow bonding") or adhesive bonding.

The support bumps 31 rest on the mass 23 of the waveguide 2 in the form of the metallic layer and on the metallization 13 of the radiating element, the HF bump 4 on the central conductor 22 and on the resonator 12. By means of the flip chip receipt set a high db of the bumps 4.31 of 60 μm. Using flip-chip bonding, this high db can be set with an accuracy of <1 μm, which is the case at high frequencies, e.g. B. millimeter waves with f> 20 GHz, is of great importance. In contrast, wire bonds or wire bonds show a significantly higher disturbance in wave propagation. For thermocompression bonding, the use of bumps 4.31 made of gold is particularly advantageous.

The gap between the resonator 12 and the waveguide 2 produced by the bumps 31 is generally filled with air. An electric field E forms between the resonator 12 and the metallic layer 23 within the gap. This arrangement is analogous to a microstrip line in which the resonator 12 corresponds to the strip 15 '. The substrate 14 then essentially consists of the contents of the gap, e.g. Air or vacuum.

In this exemplary embodiment, the resonator 12 borders directly on the gap. However, it is also possible for one or more layers to be additionally applied between the resonator 12 and the gap. This is easily possible with the flip-chip technology, because the radiation element 1 can be finished separately before the bonding. For example, it is possible to combine an MMIC with an antenna without any particular additional effort. This antenna thus has the advantage that, due to the low dielectric constant ε _{r of} the gap content, the radiation efficiency is very high, or is optimal in the case of air.

Figure 3 shows a plot of the amount of adjustment or input reflection (mag Sll) in dB against the radiation frequency f in GHz. Each graph corresponds to a different height db of the bumps 4.31 and thus a different gap height.

It can be seen that by adjusting the gap height, the center frequency of the antenna can easily be set in a wide range of approximately 10 GHz.

Claims

claims

1. antenna, having

a radiation element (1) which contains at least one substrate (11) and at least one planar resonator (12) applied to the substrate (11),

- a planar waveguide (2), d a d u r c h g e k e n n z e i c h n e t, d a ß

- The resonator (12) is separated from the waveguide (2) by a gap which is parallel to a plane of the resonator

(12) lies.

2. Antenna according to claim 1, wherein the radiation element (1) by means of a plurality of support bumps (31) on the waveguide (2) is fixed.

3. Antenna according to claim 2, in which the bumps (4.31) are between 40 μm and 1000 μm, in particular between 40 μm and 100 μm, high.

4. Antenna according to one of the preceding claims, wherein the waveguide (2) is a coplanar waveguide.

5. Antenna according to claim 4, wherein the resonator (12) faces the waveguide (2) and is electrically connected to a center conductor (22) of the waveguide (2).

6. Antenna according to claim 5, wherein the resonator (12) with the center conductor (22) by means of at least one RF bump (4) is electrically connected.

6. Antenna according to one of claims 1 to 3, wherein the waveguide (2) is a microstrip waveguide

7. Antenna according to one of the preceding claims, in which at least the substrate (11) of the radiating element (1) or a substrate (21) of the waveguide (2) consists of A1 ₂ 0 ₃ or glass.

8. A method for producing an antenna according to one of the preceding claims, in which the radiation element (1) is attached to the waveguide (2) by means of a flip-chip technology.

9. The method according to claim 8, wherein the gap is filled with a hardening liquid after the application of the flip-chip technique.