Patent Description:
In the state of the art, biconical antenna assemblies are typically used in electromagnetic interference (EMI) testing such as immunity testing or emissions testing. The biconical antenna assembly corresponds to a broadband antenna assembly that comprises of two roughly conical conductive objects that extend to opposite directions, but nearly touching each other via the ends facing each other. Hence, the biconical antenna assemblies are also called butterfly antenna assemblies due to their appearance. Furthermore, a two-dimensional version of the biconical antenna assembly is called bowtie antenna assembly, which is often used for short-range ultra-high frequency (UHF) television reception.

In general, the biconical antenna assemblies have dipole-like characteristics with a wider bandwidth achieved due to the specific structure, namely the roughly conical conductive objects.

The EMC standards require a frequency range between <NUM> and <NUM> to be tested. For testing purposes, the biconical antenna assemblies are connected to an amplifier such that the frequency range between <NUM> and <NUM> can be covered appropriately. However, the biconical antenna assemblies known in the state of the art have a bad matching at frequencies in the range of <NUM> to <NUM>, resulting in a lower field strength which is disadvantageous for testing purposes. Accordingly, it is necessary to use a more powerful amplifier for testing in order to reach the required field strength in the lower frequency range of <NUM> to <NUM> due to the bad matching of the biconical antenna assemblies known in the state of the art.

However, this increases the overall costs for testing, as the powerful amplifier is more expensive.

<CIT> shows an extensible top-loaded biconical antenna that is modified to improve low frequency performance. The biconical antenna includes a balun and a pair of conical outrigger assemblies coupled to the balun, wherein a conducting tophat plate is removably attached to the ends of each outrigger assembly.

<CIT> shows a monocone antenna that includes a conical radiation element having a feed point at a vertex of the conical radiation element.

In <CIT>, a compact, omnidirectional, broadband biconical antenna is shown that has a first segment with its top coincident with a horizontal plane.

<CIT> shows a short wave antenna suitable for the transmission of an extremely wide band of frequencies.

Accordingly, there is a need for a biconical antenna assembly that can be used with amplifiers at low frequencies in order to ensure EMC testing in an appropriate manner.

The invention provides a biconical antenna assembly for electromagnetic compatibility (EMC) testing. The biconical antenna assembly has an antenna feeding point, a first antenna structure and a second antenna structure. The first antenna structure and the second antenna structure extend from the antenna feed point towards opposite directions. The biconical antenna assembly comprises at least one additional capacitive structure that is attached to a most distal point of the first antenna structure or the second antenna structure from the antenna feed point. The additional capacitive structure has an ellipsoid shape or a substantially spherical shape or a perfectly spherical shape.

The invention is based on the finding that the biconical antenna assembly has an improved matching compared to the biconical antenna assemblies known in the state of the art due to the additional capacitive structure that is attached to the respective antenna structure. In general, the additional capacitive structure leads to an additional capacity at the point at which the additional capacitive structure is attached to the respective antenna structure, namely the most distal point of the respective antenna structure. In fact, the additional capacitive structure increases the active surface at the distal point of the respective antenna structure.

Due the better matching, a simple amplifier can be used together with the biconical antenna assembly in order to provide the desired field strength at low frequencies, particularly in the frequency range of <NUM> to <NUM>. Particularly, the field strength achieved is improved by <NUM> dB up to <NUM> dB.

Accordingly, an EMC test can be conducted while using the biconical antenna assembly according to the invention together with a simple amplifier, wherein the simple amplifier may have a lower output power compared to the ones used previously, particularly when testing in the frequency range of <NUM> to <NUM>. This is possible due to the improved matching of the biconical antenna assembly which is achieved by the additional capacitive structure located at the most distal point of the respective antenna structure.

The most distal point from the antenna feed point may correspond to the point of the respective antenna structure that has the largest distance to the antenna feed point. According to an embodiment, the most distal point of the respective antenna structure is located on a center axis of the respective antenna structure.

Generally, the antenna structures are electrically conductive.

Moreover, the at least one additional capacitive structure may also be established in an electrically conductive manner, wherein the additional capacitive structure provides an additional capacity to the entire biconical antenna assembly.

The ellipsoid shape ensures that the additional capacitive structure has an electromagnetic effect on the biconical antenna assembly, particularly the respective antenna structure to which the additional capacitive structure is attached. Generally, the ellipsoid has three pairwise perpendicular axes of symmetry which intersect at a center of symmetry, called the center of the ellipsoid. The center of the ellipsoid may be located on the center axis of the respective antenna structure to which the additional capacitive structure is connected. The center axis of the respective antenna structure may also run through the center of the antenna feed point.

In case of a substantially spherical shape, the additional capacitive structure relates to a ball with minor deviations, for instance at a side that is facing the respective antenna structure in order to improve the connection between the additional capacitive structure and the respective antenna structure. For instance, the additional capacitive structure may deviate from the perfectly spherical shape by a flat spot that is used for connecting the additional capacitive structure to the respective antenna structure.

In case of a perfectly spherical shape, the additional capacitive structure may be connected to the respective antenna structure via a coupling element, particularly an electrically conductive coupling element, or rather a layer of adhesive, particularly an electrically conductive adhesive. The coupling element may relate to the disc or rather place that is part of the respective antenna structure. The coupling element may have a receptacle for the additional capacitive structure, in particular wherein the receptacle has a partly spherical receiving surface for accommodating the additional capacitive structure. A film of adhesive may be provided on the receiving surface such that the additional capacitive structure is adhered to the receptacle. The layer of adhesive may have a certain thickness, thereby ensuring a proper connection of the additional capacitive structure. Generally, a proper mechanical connection is ensured between the additional capacitive structure and the respective antenna structure to which the additional capacitive structure is attached.

According to an aspect, the first antenna structure and the second antenna structure each have a substantially conical geometry. Particularly, the first antenna structure and the second antenna structure each have a first conical portion and a second conical portion, which are connected with each other via their wide ends. The respective antenna structures ensure that the entire biconical antenna assembly has its biconical shape, particularly each of the antenna structures itself is biconically shaped due to the first and second conical portions.

The biconical antenna assembly may be foldable, particularly the first and/or second antenna structure. For this functionality, the respective conical portions of the respective antenna structures can be folded accordingly. Thus, the entire biconical antenna assembly can be folded in order to obtain a compact size for transporting.

Another aspect provides that the additional capacitive structure has a galvanic connection to the most distal point of the respective antenna structure. Therefore, the additional capacitive structure is connected with the respective antenna structure in an electrically conductive manner.

The additional capacitive structure has a three-dimensional geometry. Thus, the additional capacitive structure is different to a disc or rather a plate that may terminate the respective antenna structure. The disc or rather plate may connect several radiating conductors of the respective antenna structure, thereby establishing the respective antenna structure. However, the additional capacitive structure may be attached to the disc or rather plate in a galvanic manner, as the disc or rather plate may be associated to the most distal point of the respective antenna structure.

According to another aspect, the biconical antenna assembly comprises two additional capacitive structures, namely a first additional capacitive structure and a second additional capacitive structure. The first additional capacitive structure is attached to a most distal point of the first antenna structure from the antenna feed point. The second additional capacitive structure is attached to a most distal point of the second antenna structure from the antenna feed point. Therefore, two additional capacitive structures are provided that are located at the most distal ends of the biconical antenna assembly, particularly the respective antenna structures. The additional capacitive structures may be shaped and/or configured in a similar manner such that the biconical antenna assembly is adapted in a symmetric manner concerning its capacitive properties. Generally, the antenna structures each may have a respective center axis, wherein their center axes coincidence with each other. The respective additional capacitive structures each may have a center that is located on the center axes that also run through the center of the antenna feed point. Furthermore, the most distal point of the respective antenna structure may also be located on its respective center axis.

Particularly, two additional capacitive structures are provided that are located at the most distal ends of the biconical antenna assembly. The biconical antenna assembly is symmetrically shaped, wherein the antenna feed point is located in the center of symmetry. The entire biconical antenna assembly has a symmetric geometry. The symmetry of the biconical antenna assembly may be established by the additional capacitive structures that are located at the most distal points of the respective antenna structures to which the additional capacitive structures are attached.

Another aspect provides that the at least one additional capacitive structure is configured to provide improved matching characteristics of the biconical antenna assembly. The additional capacity provided by the additional capacitive structure adapts the matching characteristics of the biconical antenna assembly. Accordingly, the biconical antenna assembly may be connected with an amplifier that can be operated at lower output power compared to the ones used in the state of the art in order to achieve the desired field strength at low frequencies, namely in the frequency range between <NUM> and <NUM>.

Further, the antenna structures nearly touch each other at their ends facing the antenna feed point. Put differently, the antenna structures nearly touch each other at those ends that are not assigned to the additional capacitive structure since the additional capacitive structures are attached to the most distal points of the respective antenna structure from the antenna feed point. The antenna structure ends facing each other correspond to those that are located next to the antenna feed point.

According to a certain embodiment, the first antenna structure and/or the second antenna structure are/is established by several radiating conductors. Particularly, the several radiating conductors are interconnected with each other at an end facing away from the antenna feed point, namely the most distal point. A light weight and compact design of the entire biconical antenna assembly can be ensured by using several radiating conductors, particularly in case the radiating conductors are established by rods. However, the several radiating conductors may also be established by plates.

Furthermore, the entire biconical antenna assembly may be established in a foldable manner due to the several radiating conductors that can be fold with respect to each other in order to establish a compact transport state of the biconical antenna assembly.

The several radiating conductors of the respective antenna structure may be orientated with respect to each other such that the respective antenna structure has a substantially (bi-)conical geometry. Therefore, the several radiating conductors may run in a non-parallel manner from the antenna feed point towards their free ends. In fact, the several radiating conductors may be inclined with respect to each other, particularly inclined to a center axis of the respective antenna structure in the same manner, thereby establishing the conical shape of the respective antenna structure, particularly the respective conical portion.

Another aspect provides that the respective antenna structure has an end face at which the most distal point of the respective antenna structure from the antenna feed point is provided. The additional capacitive structure is attached to the most distal point at the end face. Particularly, a connecting member is located within the end face, which connects several individual radiating conductors of the respective structure, namely in an electrically conductive manner. Hence, the connecting member is part of the respective antenna structure.

The end face of the respective antenna structure may encompass the most distal portion of the antenna structure.

For instance, the end face also encompasses the connecting member via which the several individual radiating conductors are connected with each other in an electrically conductive manner, which together establish the respective antenna structure. The connecting member may correspond to a plate or a disc to which the several individual radiating conductors are electrically connected.

The connecting member may also be used for being connected with the additional capacitive structure in a galvanic manner, as the connecting member, for instance the plate or the disc, provides a connection interface for the additional capacitive structure.

Hence, the additional capacitive structure may extend away from the end face in direction facing away from the antenna feed point. The additional capacitive structure may be attached to the connecting member located within the end face of the respective antenna structure in a galvanic manner. Thus, the three-dimensional additional capacitive structure extends away from the respective end face in a direction that is facing away from the antenna feed point.

In other words, the respective additional capacitive structure corresponds to the most distal end of the biconical antenna assembly, as it is connected to the end face of the respective antenna structure, namely the distal point of the respective antenna assembly. Simultaneously, the respective additional capacitive structure extends away from the respective end face of the antenna structure in a direction that faces away from the antenna feed point located in the center of the biconical antenna assembly, particularly the center of symmetry.

In general, the additional capacitive structures are attached to the connecting members, for instance by means of an electrically conductive connecting member such as a screw or rather an electrically conductive adhesive.

Further aspects and advantages of the claimed subject matter will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings. In the drawings,.

In <FIG>, a biconical antenna assembly <NUM> is shown that comprises an antenna feed point <NUM> located in the center of the biconical antenna assembly <NUM>.

The biconical antenna assembly <NUM> further comprises a first antenna assembly <NUM> as well as a second antenna assembly <NUM> which are both extending from the antenna feed point <NUM> in opposite directions, but nearly touching each other at their ends facing the antenna feed point <NUM>.

The antenna structures <NUM>, <NUM> each comprise a substantially (bi-)conical geometry, wherein the respective antenna structure <NUM>, <NUM> has a first conical portion <NUM> as well as a second conical portion <NUM>. The respective conical portions <NUM>, <NUM> are connected with each other at their wide ends, as the respective cones of the conical portions <NUM>, <NUM> are orientated in opposite directions.

As shown in <FIG>, the respective antenna structures <NUM>, <NUM> are established by several radiating conductors <NUM> that are made of electrically conductive rods or rather bars. The radiating conductors <NUM> are orientated with respect to each other and with respect to a center axis A of the entire biconical antenna assembly <NUM> such that the respective antenna structures <NUM>, <NUM> each have the (bi-)conical geometry. In fact, the center axis A of the entire biconical antenna assembly <NUM> coincidences with center axes A', A" of the respective antenna structures <NUM>, <NUM>.

The several radiating conductors <NUM> can be configured such that the biconical antenna assembly <NUM> can be folded in order to provide a compact transport state. Thus, the several radiating conductors <NUM> may be moved with respect to a center element <NUM> that runs along the center axis A', A" of the respective antenna structure <NUM>, <NUM>.

When folding the respective antenna structure <NUM>, <NUM>, the radiating conductors <NUM> associated with the second conical portion <NUM> may be moved inwardly towards the antenna feed point <NUM>, wherein the radiating conductors <NUM> associated with the first conical portion <NUM> are moved towards the center element <NUM>, thereby ensuring the compact state of the biconical antenna assembly <NUM>.

In addition, the biconical antenna assembly comprises a first additional capacitive structure <NUM> as well as a second additional capacitive structure <NUM>. The respective additional capacitive structures <NUM>, <NUM> are each attached to a most distal point <NUM>, <NUM> of the respective antenna assemblies <NUM>, <NUM> to which the respective additional capacitive structure <NUM>, <NUM> is attached.

In other words, the first additional capacitive structure <NUM> is attached to the first antenna structure <NUM> at the most distal point <NUM> of the first antenna structure <NUM> from the antenna feed point <NUM>. The second additional capacitive structure <NUM> is attached to the most distal point <NUM> of the second antenna structure <NUM> from the antenna feed point <NUM>.

The respective additional capacitive structures <NUM>, <NUM> are connected to the respective antenna structures <NUM>, <NUM> via a galvanic connection.

As shown in <FIG>, the additional capacitive structure <NUM>, <NUM> generally has a three-dimensional geometry, namely a perfectly spherical shape.

Since both additional capacitive structures <NUM>, <NUM> are established in a similar manner, the entire biconical antenna assembly <NUM> is symmetrically shaped, in particular wherein the antenna feed point <NUM> is located in the center of symmetry C of the biconical antenna assembly <NUM>. Hence, the antenna feed point <NUM> is also located on the center axis A.

The additional capacitive structures <NUM>, <NUM> provide an improved matching characteristics of the biconical antenna assembly <NUM> due to the additional capacity provided at the most distal points <NUM>, <NUM> of the respective antenna structures <NUM>, <NUM>.

Moreover, the respective antenna structures <NUM>, <NUM> each have a connecting member <NUM> to which the individual radiating conductors <NUM> of the respective antenna structures <NUM>, <NUM> are connected. The connecting member <NUM> may be established by a disc or rather a plate that can be moved with respect to the center element <NUM> when folding the biconical antenna assembly <NUM>.

In fact, the connecting member <NUM> is connected to the several individual radiating conductors <NUM> in an electrically conductive manner, thereby establishing the respective antenna structure <NUM>, <NUM>. Put differently, the first antenna structure <NUM> and/or the second antenna structure <NUM> each comprise the several individual radiating conductors <NUM> as well as the connecting member <NUM> to which the individual radiating conductors <NUM> are electrically connected.

The connecting member <NUM> is located at an end face <NUM> of the respective antenna structure <NUM>, <NUM> at which the most distal point <NUM>, <NUM> of the respective antenna structure <NUM>, <NUM> is also provided.

In the shown embodiment, the most distal points <NUM>, <NUM> are also located at the end faces <NUM> of the respective antenna structures <NUM>, <NUM>.

Accordingly, the additional capacitive structures <NUM>, <NUM> are attached to the connecting members <NUM>, for instance by means of a screw or rather an electrically conductive adhesive.

The screw allows to detach the additional capacitive structures <NUM>, <NUM>, thereby supporting the folding of the biconical antenna assembly <NUM>.

In <FIG>, an alternative embodiment of the biconical antenna assembly <NUM> is shown that differs from the one shown in <FIG> in that only a single additional capacitive structure <NUM> is provided such that the entire biconical antenna assembly <NUM> is not symmetrically shaped.

The additional capacitive structure <NUM> is however attached to the most distal point <NUM> of the first antenna structure <NUM>, namely in a similar manner as described above with respect to the embodiment shown in <FIG>.

In addition, the shape of the additional capacitive structure <NUM> differs from the perfectly spherical shape of the additional capacitive structures <NUM>, <NUM> shown in <FIG>, as the additional capacitive structure <NUM> shown in <FIG> corresponds to an ellipsoid. In fact, the additional capacitive structure <NUM> has only a substantially spherical shape.

Generally, the additional capacitive structure <NUM>, <NUM> may have a flat spot that faces the connecting member <NUM> such that the additional capacitive structure <NUM>, <NUM> can be connected to the respective connecting member <NUM> easily, namely via the flat spot, resulting in a deviation from the perfect spherical shape.

Claim 1:
A biconical antenna assembly for electromagnetic compatibility testing, wherein the biconical antenna assembly (<NUM>) has an antenna feeding point (<NUM>), a first antenna structure (<NUM>) and a second antenna structure (<NUM>), wherein the first antenna structure (<NUM>) and the second antenna structure (<NUM>) extend from the antenna feed point (<NUM>) towards opposite directions, wherein the biconical antenna assembly (<NUM>) comprises at least one additional capacitive structure (<NUM>, <NUM>) that is attached to a most distal point (<NUM>, <NUM>) of the first antenna structure (<NUM>) or the second antenna structure (<NUM>) from the antenna feed point (<NUM>), characterized in that the at least one additional capacitive structure (<NUM>, <NUM>) has an ellipsoid shape or a substantially spherical shape or a perfectly spherical shape.