Patent Description:
In wireless communication networks there is radio equipment that in many cases comprises so-called advanced antenna system (AAS), for example <NUM> mobile communication system. AAS is a key component to improve capacity and coverage by making use of the spatial domain, and a challenge is to develop cost efficient technologies and building practice to meet market cost demands on this type of products.

In the mm-wave area, such as about <NUM> and above, it is attractive using a highly integrated building practice based on multi-layer PCB (printed circuit board) or LTCC (low temperature cofired ceramics), or similar multi-layer technologies. Hence there is a need of antenna array designs that are suitable to be realized and produced in multi-layer technology.

Classical patch antennas printed on dielectric substrates suffer from excitation of substrate waves, which interferes with neighboring antenna elements in an antenna array system as well as causing edge effects. Cavity-backed patch antennas suppress substrate waves, since the cavity hinders the waves to propagate into the dielectric substrate, for example as described in "<NPL>).

However, such wideband cavity backed patch antennas are limited by their deteriorating cross-polarization ratio, which is detrimental to the wideband dual polarized antenna array performance. Furthermore, the wideband cavity patch antenna also suffers from feed radiation, which causes among others asymmetry in the radiation pattern.

Aperture feeding of a cavity-backed microstrip patch antenna is described in "<NPL>). A disadvantage of aperture feeding, however, is that a cavity is required below the feeding aperture which in turn requires room in the PCB layers below the aperture. The thickness of the below PCB layers thus needs to be increased, and in these layers it will also be less available area for power distribution arrangements for feeding the antenna or antenna array.

<CIT> discloses a probe-fed stacked patch antenna element.

<CIT> discloses capacitive edge coupling probes that are adapted to excite two stacked square patch elements.

<NPL>, discloses using a multi-layer PCB technology incorporating Teflon-based laminates to implement a horn-like antenna for millimeter-wave applications.

<NPL>, discloses solutions for developing low-cost 3D multilayer integration and packaging on organic substrate Liquid Crystal Polymer (LCP) and paper substrate. Microstrip antenna arrays are disclosed for this technology with antenna elements in an embedded layer and in a top layer.

<CIT> discloses a microstrip antenna device with stacked conductive patches.

<CIT>, representing a prior right under Article <NUM>(<NUM>) EPC, discloses an antenna formed in a multi-layer OCB where a cavity is formed in the multi-layer PCB that includes multiple horizontal PCB layers which are stacked in a vertical direction. An antenna patch is arranged within the cavity and a feed connection extends through a conductive plate to a feed point on the antenna patch. The antenna includes a parasitic patch arranged above the antenna patch.

There is thus a need for a cavity-backed patch antenna element where feed radiation is reduced, which results in a more symmetrical and better antenna radiation characteristic, and where cross-polarization radiation performance is improved, and an antenna array comprising such antenna elements.

It is an object of the present disclosure to provide a cavity-backed patch antenna element where feed radiation is reduced, which results in a more symmetrical and better antenna radiation characteristics, and where cross-polarization radiation performance is improved. It is also an object of the present disclosure to provide an antenna array comprising such antenna elements.

Said object is obtained by means of an antenna element comprising a lower conducting plane, an upper conducting plane and an upper dielectric layer structure that is positioned between the conducting planes. The upper dielectric layer structure comprises a plurality of conducting vias that electrically connect the conducting planes to each other and circumvent an upper radiating patch formed in the upper conducting plane. The conducting vias circumvent at least one intermediate radiating patch that is formed in the upper dielectric layer structure. A lowest intermediate radiating patch that is closest to the lower conducting plane is connected to a feed arrangement that comprises at least one feeding probe that is comprised in the antenna element and extends via a corresponding aperture in the lower conducting plane and is directly electrically connected to the lowest intermediate radiating patch. A first distance between the lowest intermediate radiating patch and the lower conducting plane falls below a second distance between the upper radiating patch and a closest intermediate patch, being the intermediate patch that is closest to the upper radiating patch. Each feed arrangement is connected to a power distribution arrangement that extends in a lower dielectric layer structure that is comprised in the antenna element, where the lower conducting plane is positioned between the upper dielectric layer structure and the lower dielectric layer structure. The lower dielectric layer structure comprises at least one signal layer comprising the power distribution arrangement, and at least one dielectric layer for each signal layer.

This provides advantages related to providing antenna radiation characteristics and cross-polarization radiation performance that are improved compared to prior art, further enabling reduced feed radiation. This also enables a multilayer structure for a versatile power distribution arrangement, where undesired radiation from the power distribution arrangement is prevented.

According to some aspects, the upper dielectric structure comprises a separate dielectric layer formed for each radiating patch.

This provides an advantage of an efficient building structure.

According to some aspects, the upper conducting plane comprises an electrically conducting frame to which the vias are connected.

This provides an advantage of having an efficient connection between the vias.

According to some aspects, the upper dielectric layer structure is formed as a separate upper part and where the lower dielectric layer structure is formed as a separate lower part, where furthermore the upper dielectric layer structure is adapted to be surface-mounted to the lower dielectric layer structure.

This provides an advantage of enabling efficient manufacturing.

According to some aspects, the upper dielectric layer structure comprises upper feeding probe parts and a first lower conducting plane, and the lower layer structure comprises lower feeding probe parts and a second lower conducting plane.

Said object is also obtained by means of an array antenna arrangement comprising a plurality of antenna elements according to the above. The array antenna arrangement further comprises a feed assembly comprising the power distribution arrangements.

In this manner, all the advantages discussed above for an antenna element are applied for an array antenna.

According to some aspects each antenna element is adapted to be surface-mounted to a common dielectric layer structure.

Preferably, the common dielectric layer structure comprises a first conducting plane, a second conducting plane and a third conducting plane. The first conducting plane comprises a first ground plane, the second conducting plane comprises a feeding network and is separated from the first conducting plane by a first dielectric layer, and the third conducting plane comprises a second ground plane and is separated from the second conducting plane by a second dielectric layer. Each antenna element comprises a lower dielectric layer structure that comprises at least one upper feeding sub-probe part that is connected to the power distribution arrangements and the common dielectric layer structure comprises a lower feeding sub-probe part for each upper feeding sub-probe part. The lower feeding sub-probe parts are connected to the feeding network in the second conducting plane.

This provides an advantage of enabling an alternative efficient manufacturing.

With reference to <FIG>, showing a perspective side view of a cavity-backed patch antenna element and <FIG>, showing a schematic cut-open side view of the cavity-backed patch antenna element, a first example will now be described.

The antenna element <NUM> comprises a lower conducting plane <NUM>, an upper conducting plane <NUM> and an upper dielectric layer structure <NUM> that is positioned between the conducting planes <NUM>, <NUM>, where the upper dielectric layer structure <NUM> comprises a plurality of conducting vias <NUM> (only a few indicated for reasons of clarity) that electrically connect the conducting planes <NUM>, <NUM> to each other. The vias <NUM> circumvent an upper radiating patch <NUM> formed in the upper conducting plane <NUM>, and a lowest intermediate radiating patch <NUM> that is formed in the upper dielectric layer structure <NUM>, where the lowest intermediate radiating patch <NUM> is closer to the lower conducting plane <NUM> than the upper radiating patch <NUM>. It is to be noted that all vias <NUM> are not shown in <FIG>, there is a gap for reasons of clarity, but of course the vias <NUM> are intended to run evenly distributed and completely circumvent the patches <NUM>, <NUM>.

In this manner, a cavity is formed in the upper dielectric layer structure <NUM>, being limited by the vias <NUM>, where the lower conducting plane <NUM> constitutes a cavity floor. The cavity height and shape are tuning parameters, which may vary for different bandwidth requirements.

Between the patches <NUM>, <NUM> there is an upper first dielectric layer <NUM>, and between the lowest intermediate radiating patch <NUM> and the lower conducting plane <NUM> there is an upper second dielectric layer <NUM>. According to some aspects, the upper conducting plane <NUM> comprises an electrically conducting frame <NUM> to which the vias <NUM> are connected.

According to the present disclosure, the lowest intermediate radiating patch <NUM> is connected to a feed arrangement that comprises a first feeding probe <NUM> and a second feeding probe <NUM>, where the feeding probes <NUM>, <NUM> extend via corresponding apertures <NUM>, <NUM> in the lower conducting plane <NUM> and are electrically connected to the lowest intermediate radiating patch <NUM>.

A power distribution arrangement <NUM>, <NUM> (only schematically indicated) extends in a lower dielectric layer structure <NUM>, where the lower conducting plane <NUM> is positioned between the upper dielectric layer structure <NUM> and the lower dielectric layer structure <NUM>. The power distribution arrangement <NUM>, <NUM> is adapted to feed the lowest intermediate radiating patch <NUM> with two orthogonal polarizations via the feeding probes <NUM>, <NUM>.

The lower dielectric layer structure <NUM> comprises a first signal layer <NUM>, comprising the power distribution arrangement <NUM>, <NUM> and a first lower dielectric layer <NUM>. The lower dielectric layer structure <NUM> further comprises a bottom conducting plane <NUM> and a second lower dielectric layer <NUM> positioned between the bottom conducting plane <NUM> and the first signal layer <NUM>. In this way, the first signal layer <NUM> is comprised in a stripline structure.

Here, the power distribution arrangement <NUM>, <NUM> is shown to extend in one signal layer <NUM>, but according to some aspects the lower dielectric layer structure <NUM> comprises several signal layers in which a power distribution arrangement extends.

According to some aspects, there can be one or more further intermediate radiating patches between the lowest intermediate radiating patch <NUM> and the upper radiating patch <NUM>. With reference to <FIG>, showing a schematic cut-open side view of a cavity-backed patch antenna element <NUM>' according to a second example, there is an upper intermediate radiating patch <NUM> positioned between the lowest intermediate radiating patch <NUM> and the upper radiating patch <NUM> in an alternative upper dielectric layer structure <NUM>'. Between the upper radiating patch <NUM> and the upper intermediate radiating patch <NUM> there is an upper first dielectric layer <NUM>', and between the intermediate patches <NUM>, <NUM> there is an upper third dielectric layer <NUM>'.

In the present context, the term intermediate radiating patch relates to the fact that such a patch lies between the upper radiating patch <NUM> and the lower conducting plane <NUM>.

According to some aspects, a first distance d1 between the lowest intermediate radiating patch <NUM> and the lower conducting plane <NUM> falls below a second distance d2, d2' between the upper radiating patch <NUM> and a closest intermediate patch <NUM>, <NUM>. The first distance d1 is preferably relatively small.

As indicated with dashed lines in <FIG>, a plurality of antenna elements can be positioned side by side to form an array antenna as will be discussed below; alternatively the conducting layers <NUM>, <NUM>, <NUM> can continue as ground planes outside the antenna element structure shown.

With reference to <FIG>, showing a top view of an array antenna arrangement, and <FIG>, showing a side view of an array antenna arrangement, an array antenna arrangement <NUM> comprises a plurality of antenna elements 1a, 1b, 1c, 1d, 1e, 1f, <NUM>, <NUM>, 1i and a feed assembly <NUM> comprising corresponding power distribution arrangements <NUM>, <NUM>. The feed assembly <NUM> comprises a plurality of branches <NUM>, <NUM> (only schematically indicated in <FIG>), where each branch <NUM>, <NUM> is adapted to feed two antenna elements 1a, 1b, such that each branch <NUM>, <NUM> is adapted to feed a sub-array 1a, 1b. According to some aspects, the feed assembly <NUM> is connected to radio frequency, RF, circuitry <NUM>.

According to some aspects, each branch <NUM>, <NUM> is adapted to feed any number of antenna elements that will constitute a sub-array. As indicated with dashed lines in <FIG>, the array antenna arrangement <NUM> can have any suitable size, comprising any number of antenna elements.

In <FIG>, for each antenna element 1a, 1b, 1c, 1d, 1e, 1f, <NUM>, <NUM>, 1i, a corresponding upper radiating patch 6a, 6b, 6c, 6d, 6e, 6f, <NUM>, <NUM>, 6i is shown.

According to some aspects, also with reference to <FIG> that shows a schematic cut-open side view of a cavity-backed patch antenna element <NUM> according to a third example, for each antenna element <NUM>; 1a, 1b, 1c, 1d, 1e, 1f, <NUM>, <NUM>, 1i, each upper dielectric layer structure <NUM> is formed as a separate upper part and the lower dielectric layer structure <NUM> is constituted by a common feeding arrangement, where a plurality of upper dielectric layer structures <NUM> are adapted to be surface-mounted to the lower dielectric layer structure <NUM>. As indicated with dashed lines in <FIG>, the lower dielectric layer structure <NUM> extends in accordance with the extension of the array antenna arrangement <NUM>.

For this purpose, each upper dielectric layer structure <NUM> comprises upper feeding probe parts 9a and a first lower conducting plane 2a, and the lower layer structure <NUM> comprises lower feeding probe parts 9b and a second lower conducting plane 2b. Furthermore, before surface-mounting takes place, a solder coating, conducting glue/epoxy or similar <NUM> is applied between the first lower conducting plane 2a and the second lower conducting plane 2b, in <FIG> the solder coating <NUM> is shown applied to the first lower conducting plane 2a. Of course, the solder coating <NUM> can be applied to the second lower conducting plane 2b instead.

In view of the above, with reference to <FIG>, <FIG> and <FIG>, there is an example method, not being part of the present invention, for manufacturing an array antenna arrangement <NUM>. For each antenna element <NUM>; 1a, 1b, 1c, 1d, 1e, 1f, <NUM>, <NUM>, 1i in the array antenna arrangement <NUM>, the method comprises:.

Alternatively, according to some aspects and with reference to <FIG> and <FIG>, where <FIG> shows a schematic cut-open side view of a cavity-backed patch antenna element <NUM> according to a fourth example, and a common dielectric layer structure <NUM>, each antenna element <NUM>; 1a, 1b, 1c, 1d, 1e, 1f, <NUM>, <NUM>, 1i is adapted to be surface-mounted to a common dielectric layer structure <NUM>.

The common dielectric layer structure <NUM> comprises a first conducting plane 36a, a second conducting plane 36b and a third conducting plane 36c. The first conducting plane 36a comprises a first ground plane, the second conducting plane 36b constitutes a signal layer, comprises a feeding network <NUM> and is separated from the first conducting plane 36a by a first dielectric layer <NUM>, and where the third conducting plane 36c comprises a second ground plane and is separated from the second conducting plane 36b by a second dielectric layer <NUM>.

Each antenna element <NUM>; 1b, 1c, 1d, 1e, 1f, <NUM>, <NUM>, 1i comprises a lower dielectric layer structure <NUM> that comprises at least one upper feeding sub-probe part 32a that is connected to the power distribution arrangements <NUM>, <NUM>. The common dielectric layer structure <NUM> comprises a lower feeding sub-probe part 32b for each upper feeding sub-probe part 32a, and the lower feeding sub-probe parts 32b are connected to the feeding network <NUM> in the second conducting plane 36b. As indicated with dashed lines in <FIG>, the common dielectric layer structure <NUM> extends in accordance with the extension of the array antenna arrangement <NUM>.

Furthermore, before surface-mounting takes place, a solder coating <NUM> is applied between the bottom ground plane <NUM> and the first conducting plane 36a; in <FIG> the solder coating <NUM> is shown applied to the bottom ground plane <NUM>. Of course, the solder coating <NUM> can be applied to the first conducting plane 36a instead.

Here, the feeding network <NUM> is shown to extend in one signal layer in the form of the conducting plane 36b, but according to some aspects the common dielectric layer structure <NUM> comprises several conducting planes in which the feeding network extends.

In view of the above, with reference to <FIG>, <FIG> and <FIG>, there is an example method, not being part of the present invention, for manufacturing an array antenna arrangement <NUM>. The method comprises:.

The present disclosure is not limited to the above, but may vary within the scope of the appended claims. For example, according to some aspects, the lower dielectric layer structure <NUM> comprises the first signal layer <NUM>, and the first lower dielectric layer <NUM> only, the first signal layer <NUM> being comprised in a microstrip structure.

The antenna is made up by at least two grounded metal planes that are interconnected by via holes, were the lower plane constitutes the cavity floor while the top plane includes an aperture opening.

Each dielectric layer can according to some aspects comprise two or more sub-layers, where two or more sub-layers in a dielectric layer can be made in different dielectric materials. Each sub-layer can be grounded by means of the vias <NUM>.

The shape of cavity and/or the patch are not restricted to rectangular or circular shapes, but other shapes are of course possible such as hexagonal shapes, octagonal shapes etc. The patches in each antenna element <NUM> can according to some aspects have different mutual sizes and/or shapes.

Although not illustrated, the power distribution arrangement <NUM>, <NUM> can be surrounded by vias in order to suppress undesired radiation from the power distribution arrangement <NUM>, <NUM>.

The manufacture of an array antenna by means of surface-mounting described above with reference to <FIG> can according to some aspects be applied to individual antenna elements. In that case, as shown in <FIG>, the upper dielectric layer structure <NUM> is formed as a separate upper part and the lower dielectric layer structure <NUM> is formed as a separate lower part. In <FIG> it is indicated with dashed lines that the lower dielectric layer structure <NUM> continues, as is the case for an array antenna, but for an individual antenna element <NUM> the lower dielectric layer structure <NUM> matches the upper dielectric layer structure <NUM>.

The upper dielectric layer structure <NUM> is adapted to be surface-mounted to the lower dielectric layer structure <NUM> and comprises upper feeding probe parts 9a and a first lower conducting plane 2a. The lower layer structure <NUM> comprises lower feeding probe parts 9b and a second lower conducting plane 2b.

According to some aspects, one antenna element or a group of antenna elements can be manufactures as described with reference to <FIG> and <FIG>. A plurality of such antenna elements or groups of antenna elements can then be assembled to form an array antenna as described above with reference to <FIG> and <FIG>.

In <FIG>, <FIG>, <FIG>, and <FIG>, which each show a schematic cut-open side view of a cavity-backed patch antenna element, only one probe element9; 9a, 9b is shown although there are two probe elements.

According to some aspects, each antenna element <NUM> is single polarized and only comprises one probe element. Alternately, the each antenna element <NUM> comprises four probe elements that symmetrically feed the lowest intermediate radiating patch <NUM>. In the case of more than one probe element, each antenna element <NUM> is adapted for either dual polarization or circular polarization.

According to some aspects, the upper radiating patch <NUM> is formed in, below or above the upper conducting plane <NUM>.

Having the lowest intermediate radiating patch <NUM> positioned relatively close to the lower conducting plane <NUM> and the upper radiating patch in or near an aperture plane formed in the upper conducting plane is twofold. Firstly, the radiation from the feed probes is reduced, which results in a more symmetrical and better antenna radiation characteristic. Secondly, the cross-polarization radiation performance is significantly improved.

The power distribution layer is according to some aspects connected to further layers where routing and connections to radio components and/or ASIC:s (Application Specific Integrated Circuits) can be obtained.

Terms like orthogonal are not intended to be interpreted as mathematically exact, but as within what is practically obtainable in the present context.

Generally, the present disclosure relates to an antenna element <NUM> comprising a lower conducting plane <NUM>, an upper conducting plane <NUM> and an upper dielectric layer structure <NUM> that is positioned between the conducting planes <NUM>, <NUM>, where the upper dielectric layer structure <NUM> comprises a plurality of conducting vias <NUM> that electrically connect the conducting planes <NUM>, <NUM> to each other and circumvent an upper radiating patch <NUM> formed in, below or above the upper conducting plane <NUM>, where the conducting vias <NUM> circumvent at least one intermediate radiating patch <NUM>, <NUM> that is formed in the upper dielectric layer structure <NUM>, wherein a lowest intermediate radiating patch <NUM> that is closest to the lower conducting plane <NUM> is connected to a feed arrangement <NUM>, <NUM> that comprises at least one feeding probe <NUM>, <NUM> that extends via a corresponding aperture <NUM> in the lower conducting plane <NUM> and is electrically connected to the lowest intermediate radiating patch <NUM>.

According to some aspects, the upper dielectric structure <NUM> comprises a separate dielectric layer <NUM>, <NUM>, <NUM> formed for each radiating patch <NUM>, <NUM>, <NUM>.

According to some aspects, the upper conducting plane <NUM> comprises an electrically conducting frame <NUM> to which the vias <NUM> are connected.

According to some aspects, each feed arrangement is connected to a power distribution arrangement <NUM>, <NUM> that extends in a lower dielectric layer structure <NUM>, where the lower conducting plane <NUM> is positioned between the upper dielectric layer structure <NUM> and the lower dielectric layer structure <NUM>.

According to some aspects, the lower dielectric layer structure <NUM> comprises at least one signal layer <NUM> comprising the power distribution arrangement <NUM>, <NUM>, and at least one dielectric layer <NUM> for each signal layer <NUM>.

According to some aspects, the lower dielectric layer structure <NUM> comprises a bottom conducting plane <NUM> and at least one dielectric layer <NUM> positioned between the bottom conducting plane <NUM> and the closest signal layer <NUM>.

According to some aspects, the upper dielectric layer structure <NUM> is formed as a separate upper part and where the lower dielectric layer structure <NUM> is formed as a separate lower part, where furthermore the upper dielectric layer structure <NUM> is adapted to be surface-mounted to the lower dielectric layer structure <NUM>.

According to some aspects, the upper dielectric layer structure <NUM> comprises upper feeding probe parts 9a and a first lower conducting plane 2a, and the lower layer structure <NUM> comprises lower feeding probe parts 9b and a second lower conducting plane 2b.

According to some aspects, a first distance d1 between the lowest intermediate radiating patch <NUM> and the lower conducting plane <NUM> falls below a second distance d2, d2' between the upper radiating patch <NUM> and a closest intermediate patch <NUM>, <NUM>.

Generally, the present disclosure also relates to an array antenna arrangement <NUM> comprising a plurality of antenna elements 1a, 1b, 1c, 1d, 1e, 1f, <NUM>, <NUM>, 1i according to any one of the claims <NUM>-<NUM>, wherein the array antenna arrangement <NUM> further comprises a feed assembly <NUM> comprising the power distribution arrangements <NUM>, <NUM>.

According to some aspects, the feed assembly <NUM> comprises a plurality of branches <NUM>, <NUM>, where each branch is adapted to feed at least two antenna elements 1a, 1b, such that each branch <NUM>, <NUM> is adapted to feed a sub-array 1a, 1b.

According to some aspects, the feed assembly <NUM> is connected to radio frequency, RF, circuitry <NUM>.

According to some aspects, each upper dielectric layer structure <NUM> is formed as a separate upper part and where the lower dielectric layer structure <NUM> is constituted by a common feeding arrangement, where a plurality of upper dielectric layer structures <NUM> are adapted to be surface-mounted to the lower dielectric layer structure <NUM>.

According to some aspects, each upper dielectric layer structure <NUM> comprises upper feeding probe parts 9a and a first lower conducting plane 2a, and the lower layer structure <NUM> comprises lower feeding probe parts 9b and a second lower conducting plane 2b.

According to some aspects, each antenna element <NUM>; 1a, 1b, 1c, 1d, 1e, 1f, <NUM>, <NUM>, 1i is adapted to be surface-mounted to a common dielectric layer structure <NUM>.

Claim 1:
An antenna element (<NUM>) comprising a lower conducting plane (<NUM>), an upper conducting plane (<NUM>) and an upper dielectric layer structure (<NUM>) that is positioned between the conducting planes (<NUM>, <NUM>), where the upper dielectric layer structure (<NUM>) comprises a plurality of conducting vias (<NUM>) that electrically connect the conducting planes (<NUM>, <NUM>) to each other and circumvent an upper radiating patch (<NUM>) formed in the upper conducting plane (<NUM>), where the conducting vias (<NUM>) circumvent at least one intermediate radiating patch (<NUM>, <NUM>) that is formed in the upper dielectric layer structure (<NUM>), wherein a lowest intermediate radiating patch (<NUM>) that is closest to the lower conducting plane (<NUM>) is connected to a feed arrangement (<NUM>, <NUM>) that comprises at least one feeding probe (<NUM>, <NUM>) that is comprised in the antenna element (<NUM>) and extends via a corresponding aperture (<NUM>) in the lower conducting plane (<NUM>) and is directly electrically connected to the lowest intermediate radiating patch (<NUM>), where a first distance (d1) between the lowest intermediate radiating patch (<NUM>) and the lower conducting plane (<NUM>) falls below a second distance (d2, d2') between the upper radiating patch (<NUM>) and a closest intermediate patch (<NUM>, <NUM>), being the intermediate patch that is closest to the upper radiating patch (<NUM>), wherein each feed arrangement is connected to a power distribution arrangement (<NUM>, <NUM>) that extends in a lower dielectric layer structure (<NUM>) that is comprised in the antenna element, where the lower conducting plane (<NUM>) is positioned between the upper dielectric layer structure (<NUM>) and the lower dielectric layer structure (<NUM>), where the lower dielectric layer structure (<NUM>) comprises at least one signal layer (<NUM>) comprising the power distribution arrangement (<NUM>, <NUM>), and at least one dielectric layer (<NUM>) for each signal layer (<NUM>).