DE102020210511A1 - Antenna with a first and a second feed point - Google Patents

Abstract

It is an antenna (20) with a first and a second radiator (22a, 22b), which are each designed to emit and/or receive electromagnetic radiation. The first radiator (22a) has N helical radiator elements (24). The first and second radiators (22a, 22b) are arranged sequentially. The antenna (20) has a first feed point (28) for a first signal, the first feed point (28) lying between the first and the second radiator (22a, 22b) and having a first contact (28a) which connects the first Contacts radiator (22a) and has a second contact (28b) which contacts the second radiator (22). Furthermore, the antenna (20) has a second feed point (30) for a second signal, the second feed point (30) differing from the first feed point (28), the second feed point (30) having N contacts, with an n -th contact of the second feed point contacts an nth helical radiator element of the N helical radiator elements (24). N is a natural number greater than or equal to one (as a formula: N≥1) and n is a running index between 1 and N (as a formula: n=1..N).

Description

The invention relates to an antenna which can emit and receive signals in different directions simultaneously with vertical and circular polarization. The antenna is used, for example, on a watercraft.

For certain applications it is necessary to be able to emit both vertically polarized signals essentially in the horizontal direction and circularly polarized signals essentially in the upper hemisphere. This is the case, for example, with maritime communication systems. Communication in VHF (very high frequency, dt.: meter waves) or UHF (ultra high frequency, dt.: decimeter waves), i.e. in the frequency range between 30 MHz (megahertz) and 3000 MHz, with horizontal radiation is used. Furthermore, satellite communication is used. Here, in the VHF and/or UHF range, the signal is radiated circularly polarized in the upper hemisphere (towards the sky). Two different antenna systems are used for this, which, however, require a correspondingly large amount of space. However, space is limited on watercraft.

The object of the present invention is therefore to create an improved concept for communication by means of antennas, in particular maritime communication.

The object is solved by the subject matter of the independent patent claims. Further advantageous embodiments are the subject matter of the dependent patent claims.

Exemplary embodiments show an antenna with a first and a second radiator, which are each designed to emit and/or receive electromagnetic radiation. The first and/or the second radiator are designed, for example, as omnidirectional radiators. Different geometries are possible, in particular parts of the omnidirectional radiator can be shaped, for example, as a truncated cone.

The first radiator has N helical radiator elements, where N is a natural number greater than or equal to one. Furthermore, the first and second radiators are arranged sequentially. This means that both radiators are arranged one behind the other in a central plan view from above. Here reference is made to the typical orientation when using the antenna in operation.

The antenna has a first feed point for a first signal, the first feed point being between the first and second radiators. The first feed point has a first contact that contacts the first radiator and has a second contact that contacts the second radiator.

A feed point is understood to be a number of contacts into which the same signal is fed. The contacts are not directly (electrically) connected to each other, so there is no short circuit between the contacts. The first feed point can each have a contact at which the first signal is fed into the first radiator (first contact) and at which the first signal is fed into the second radiator (second contact). A (coaxial) line can therefore be connected to the first radiator with the first conductor (e.g. inner conductor) (first contact) and the second conductor (e.g. the outer conductor) can be connected to the second radiator (second contact). However, it is also possible to contact the first radiator with a first line and the second radiator with a second line. Then the first and the second line can carry the same signal 180° out of phase. That is, the first and second radiators are fed with a differential signal. The signal will still be the same signal even if the signal injected into two (or more) contacts is out of phase with each other.

The feed point being between the radiators refers to the fact that the first and second radiators should each radiate the first signal over their full length. That is, the first and the second contact of the first feed point are advantageously arranged on the opposite end faces of the radiators and thus between the radiators. The radiators can be fed differentially, i.e. with a 180° phase-shifted signal. This can be done by means of a balancing network, a so-called balun. In this case there are two separate lines, one per radiator, carrying the differential signal. Alternatively, no balun is used but only a coaxial line, with the inner conductor being connected to one radiator and the outer conductor being connected to the other radiator of the dipole. This is also known as "single ended excitation". However, currents can now also flow via the outside (instead of the inside) of the outer conductor. These currents are referred to as common-mode currents, which radiate but are undesirable. In this respect, the balun offers the technically better solution, the use of only one coaxial line is the more cost-effective solution.

The antenna also has a second feed point for a second signal. The second feed point differs from the first feed point. Ie a contact that is assigned to the first feed point cannot also be assigned to the second feed point. An nth contact of the second feed point contacts an nth helical radiating element of the N helical radiating elements. n is a running index, ie a natural number between 1 and N (n=1..N).

When the first signal is fed into the first feed point, the first and second radiators form a dipole that emits the first signal in a vertically polarized, substantially horizontal manner. When the second signal is correspondingly fed into the second feed point, the first radiator also forms a radiator which emits the second signal in a circularly polarized manner. The emission of the second signal takes place essentially in the upper hemisphere, ie in the direction of the sky or, if the second emitter is arranged below the first emitter, in the direction of the second emitter. However, the radiators can also be interchanged in terms of their spatial arrangement, so that the second radiator is arranged above the first radiator. Reference is again made to the typical orientation when using the antenna in service (principal direction of use).

The idea is to implement two different antenna functions, for which two different antennas are otherwise used, by means of the clever wiring of the antenna or the appropriately arranged radiators. The antenna is operated as a dipole by feeding a signal into the first feed point. The first and the second radiator each form a pole of the dipole. Both radiators emit the same signal at the same time. A vertically polarized signal can be emitted essentially horizontally by means of the dipole. Furthermore, the antenna can also be fed with a signal by means of the second feed point. However, this signal is only fed into the first radiator. The first emitter can thus emit or receive a second signal, in particular with a circular polarization, in parallel, independently of the first signal.

In other words, in a first mode, the antenna enables in particular the reception and emission of vertically polarized signals from or in the horizontal direction. Furthermore, in a second mode, the antenna enables in particular the reception and transmission of circularly polarized signals from or into the upper hemisphere, e.g. for satellite communication. In the horizontal direction as well as in the upper hemisphere, the antenna can work, for example, in the VHF and/or UHF range, in particular in a frequency band between 20 MHz and 350 MHz, in particular between 25 MHz and 170 MHz, for example between 30 MHz and 165 MHz, for VHF communication , between 210 MHz and 520 MHz, for example between 220 MHz and 512 MHz, for UHF LOS (line of sight propagation) or between 230MHz and 330MHz, for example between 240 MHz and 320 MHz, for UHF Satcom. The antenna can be operated simultaneously in the first and the second mode. Furthermore, it is also possible to operate the antenna in only one of the two modes.

In exemplary embodiments, the second signal may be injected into the nth contact with a phase shift of (n-1) times 360° divided by N to generate the circular polarization of the second signal.

In exemplary embodiments, the N helical radiator elements form an outer boundary of the first radiator. In other words, the first radiator is designed as a hollow body. In this case, the outer boundary is not to be understood as a continuous surface, but rather has openings in order to form the helical radiator elements.

In one embodiment, a first signal line carrying the first signal is routed through a cavity within the perimeter of the first radiator to contact the first feed point. Advantageously, the first signal line is routed through the first radiator over the entire length of the same. In another embodiment, a second signal line carrying the second signal is routed into the cavity within the perimeter of the first radiator to contact the second feed point. The second signal line is routed into the first radiator, for example, at least to a third of the length of the latter. In other words, the second signal line runs at least partially within the hollow body of the first radiator. The N-contacts of the second feed point are also arranged in accordance with the route that the second signal line is routed into the first radiator. The position of the second feed point also influences the impedance of the first radiator and can therefore be used to adjust the first radiator. In other words, the position of the second feed point can be selected in such a way that the impedance of the second radiator is optimized for the antenna application, e.g. for line matching. In this respect, the signal line can also be routed less than a third into the first radiator if the impedance is to be chosen accordingly. Furthermore, it is also possible to route the second signal line through the hollow body of the first radiator. Both exemplary embodiments can be combined.

The antenna can thus have a central signal feed underneath the radiators. Cables and electronic components outside of the antenna then do not disturb the radiation characteristics of the antenna and the interference is reduced to a minimum.

This means that the first signal line can contact both contacts of the first feed point. In this case, the signal line can be a coaxial cable whose inner conductor contacts one contact of the first feed point and whose outer conductor contacts the other contact of the first feed point. The first feed point can also have an electronic circuit that contacts the first signal line. The electronic circuit can process the first signal, for example carry out an impedance transformation or split the first signal into two signals with a 180° phase shift and feed the two signals into the first and the second contact of the first feed point. In the latter case, the electronic circuit for processing the first signal can be a balancing network (also referred to as a balun). This enables the first and the second radiator to be fed symmetrically between the two radiators. However, the balancing network can also be arranged outside the antenna, for example below the antenna. A further first signal line can then be routed through the cavity of the first radiator. The first signal line can contact one contact of the first feed point and the further first signal line can contact the other contact of the first feed point. The electronic circuit is designed to carry out an impedance transformation when the "single ended excitation" is used. It goes without saying that the variants of contacting the first feed point are not final.

The second signal line can contact a further electronic circuit. The further electronic circuit is optionally arranged in the cavity within the perimeter of the first radiator. The further electronic circuit can receive the second signal and duplicate it N times and provide it with an individual phase shift. The phase shift between the duplicated signals is advantageously N/360° (written out: N divided by 360 degrees). However, it is also possible to introduce N second signal lines into the cavity, so that every second signal line contacts a helical emitter element.

It goes without saying that the variants of the contacting of the first and second feed point are not final.

In a third exemplary embodiment, the second feed point is arranged in the hollow body of the first radiator. This enables the first signal to be decoupled from the second signal when both signals are radiated. It is thus possible to send and receive both signals at the same time and independently of one another.

In exemplary embodiments, the N-helical radiator elements each have a plurality of line strips routed in parallel. Due to a plurality (typically two) conduction bands per radiator element, the first radiator has two resonant frequencies (double resonance), as a result of which broadband reception and broadband emission are possible in comparison to a helical radiator element with one conduction band. Typically, the two conductor strips have different widths. The first conduction band of a helical radiating element is directly connected to the second conduction band of an adjacent radiating element of the N-helical radiating elements. That is, an electrical connection between the first line band and the second line band of the same radiating element only exists via the second line band of the adjacent radiating element. Furthermore, a distance between the first and the second line band of the same radiating element is smaller than the distance between the first and the second line band of two adjacent radiating elements. However, other embodiments are also possible. For example, a design is possible in which both line strips of the same radiating element are connected to one another. The consequence of this is that the distances between the two line strips of a radiating element can also be larger or smaller than the distance to the adjacent radiating element.

Optionally, the second conduction bands are connected to each other to form a radiating element of the dipole. The connection can also form a contact of the first radiator for the first feed point. This is advantageously done on an end face of the first radiator that faces the second radiator. The first line strips are arranged at a distance from the connection (first contact) of the second line strips and have no direct electrical contact with the connection of the second radiating elements. The electrical contact of the first tie straps to the connection (first contact) of the second tie straps takes place only via the second tie straps themselves.

The decoupling between the signals that are radiated or received by means of the first line bands and the signals that are radiated or received by means of the second line bands be caught, arises, among other things, from a common-mode rejection of the feed network with which the second signal is fed into the N contacts of the second feed point. In other words, the helix's feed network presents a high resistance to the currents on the radiating elements of the dipole. Particularly at higher frequencies, the effective distance between the feed points, ie the transit time that the first and the second signal require until they reach the other feed point, also contributes to the decoupling. The effective distance is greatest when the N-contacts for feeding in the second signal are arranged as close as possible to the end face on which the feeding point for the first signal is arranged. Further optionally, the nth contact of the second feed point contacts the first conduction band of the nth helical radiating element. The second signal can thus be fed into the first line bands and the first signal into the second line bands without the two signals interfering with one another. The same applies to receiving the signals.

Analogously, a method for producing an antenna is disclosed with the following steps: providing a first and a second radiator, each designed to emit and/or receive electromagnetic radiation, the first radiator having N helical radiator elements and the first and second radiators are arranged sequentially; arranging a first feed point of the antenna for a first signal such that the first feed point is between the first and second radiators and has a first contact contacting the first radiator and has a second contact contacting the second radiator; Arranging a second feed point of the antenna for a second signal such that the second feed point differs from the first feed point, the second feed point having N contacts, an nth contact of the second feed point contacting an nth helical radiating element of the N helical radiating elements , where N is a natural number greater than or equal to one (as a formula: N≥1) and where n is a running index between 1 and N (as a formula: n=1..N).

• 1: eine schematische Darstellung einer Antenne in Seitenansicht gemäß einem Ausführungsbeispiel; und
• 2: eine schematische Darstellung einer Antenne in Seitenansicht gemäß einem weiteren Ausführungsbeispiel.

Preferred embodiments of the present invention are explained below with reference to the accompanying drawings. Show it:

• 1 1: a schematic representation of an antenna in side view according to an embodiment; and
• 2 1: a schematic representation of an antenna in side view according to a further embodiment.

Before exemplary embodiments of the present invention are explained in more detail below with reference to the drawings, it is pointed out that identical elements, objects and/or structures that have the same function or have the same effect are provided with the same reference symbols in the different figures, so that the elements shown in different exemplary embodiments Description of these elements is interchangeable or can be applied to each other.

1 shows a schematic side view of an antenna 20. The antenna 20 has two radiators 22. FIG. The two radiators are a first radiator 22a and a second radiator 22b. The radiators 22 can emit and receive electromagnetic radiation. The first radiator 22a has N helical radiator elements 24 . In the embodiment of 1 N=4, so that a first radiating element 24a, a second radiating element 24b, a third radiating element 24c and a fourth radiating element 24d form the N helical radiating elements. The radiators 22 are designed as (hollow) omnidirectional radiators. Further, the first and second radiators 22a, 22b are arranged sequentially. That is, there is an end face 26a of the first radiator 22a and an end face 26b of the second radiator 22b, which face each other.

The antenna 20 has a first feed point 28 . The first feed point 28 includes a first contact 28a and a second contact 28b. Contacts 28a, 28b provide electrical connection between a first signal line 34 and radiators 22. Arrows 32a, 32b represent the signal flow of a first signal when the first signal is transmitted. In other words, from the point of view of radio frequency technology, the feeding end of a coaxial line is represented by a voltage source. According to this consideration, the arrows 32a, 32b can also symbolize a source of the first signal. The first signal line 34a can run through the interior of the first radiator 22a in order to contact the second radiator 22b on the end face 26b. For reasons of clarity, the first signal line 34a was only indicated inside the first radiator 22a. However, part of the first signal line 34 is shown between the radiators 22 . The arrow 32b indicates the signal flow of the first signal, or the source of the first signal, for sending it through the second radiator 22b. Furthermore, a further first signal line (not shown) can run inside the first radiator 22a. However, arrow 32a indicates the signal flow, or the source, of the first signal for transmission thereof through the first radiator 22a. The first contact 28a of the first feed point 28 is embodied on the face side of the first radiator 22a and electrically connects the (ends of) the N=4 helical radiator elements 24 to one another. On the end face of the first radiator 22a, which is opposite the end face 26a of the first radiator 22a, the N=4 helical radiator elements 24 can likewise be electrically connected to one another by means of an electrical connection 25.

Furthermore, the antenna 20 has a second feed point 30 for a second signal. The second feed point 30 has N contacts, which are not shown here for reasons of clarity.

In one exemplary embodiment, the antenna has a second signal line 34b on the inside (only shown in outline for reasons of clarity), which carries the second signal and makes contact with an electrical circuit 36 . The electrical circuit 36 is mostly covered by the fourth radiator element 24d. The electrical circuit forms N=4 phase-shifted images of the second signal. With N=4 radiator elements, the phase shift is advantageously 90°. Arrows 38a, 38b indicate the signal flow or the feeding of the phase-shifted second signals into the second emitter element 24b and the third emitter element 24c. The contacts of the second feed point are located at the tips of the arrows 38a, 38b. The contacting of the first radiator element 24a and the fourth radiator element 24d is covered by the fourth radiator element 24d.

The second feed point is well inside the first radiator, for example about a quarter of the radiator length (distance between the faces of the first radiator, away from the face 26a. This enables the simultaneous, independent transmission and reception of two signals with the radiator shown Here the first radiator has one conduction band per radiator element.

1 shows an example of the first radiator with N=4 radiator elements, a so-called quadrifilar helix. However, N can be chosen arbitrarily. Even N=1, a monofilar helix, is possible. In 1 each radiating element runs about three quarters of the circumference of the first radiator. However, the quadrifilar helix is a preferred configuration of the first radiator, since the splitting of the second signal into 4 sub-signals each phase-shifted by 90° can be implemented electrically with little effort.

Arrow 40 indicates the orientation of the antenna. In the main direction of use, the arrow 40 points up or down. That is, the second radiator 22b is arranged above or below the first radiator 22a when the antenna is arranged in the main use direction.

2 shows a schematic representation of a side view of the antenna 20 in one embodiment. In contrast to 1 the radiator elements are divided into a plurality (here 2) of parallel line strips. The first radiating element 24a comprises the first line band 24a` and the second line band 24a". The second radiating element comprises the first line band 24b' and the second line band 24b". The third radiating element comprises the first conducting band 24c' and the second conducting band 24c". The fourth radiating element comprises the first conducting band 24d' and the second conducting band 24d". The first line band is in each case wider than the second line band. However, this depends on the tuning of the antenna, for example setting a desired antenna impedance.

the end 2 it can now be seen that the radiator elements on the outer end face 26c are no longer all electrically connected to one another. Rather, only the first line strips of a radiating element are connected to the second line strips of an adjacent radiating element. For example, the first line strip 24b' of the second radiating element is electrically connected to the second line strip 24a" of the first radiating element 24a by means of an electrical connection 25'. The second line strip 24b" of the second radiating element is also electrically connected to the first line strip 24c' of the third radiating element .

Furthermore, the first line strips are not electrically connected directly to the first contact 28a, but are at a distance therefrom. However, the first contact 28a electrically connects the second conductive strips together. It is thus possible to arrange the N contacts of the second feed point almost on the end face 26a of the first radiating element without the first and second signals influencing one another. The arrows 38a, 38b and 32a, 32b are marked accordingly. Thus, the greatest possible freedom to adjust the impedance of the first radiator for the second signal is retained. Furthermore, the radiator has two different resonant frequencies per radiator element due to the parallel line bands, so that a broader bandwidth emission and a broader bandwidth reception compared to the in 1 shown embodiment is possible.

The exemplary embodiments are designed predominantly with reference to the transmission of the first and second signals with the antenna. However, it goes without saying that the antenna can also receive the first and the second signal. The signal flow then runs in the opposite direction.

Although some aspects have been described in the context of a device, it is understood that these aspects also represent a description of the corresponding method, so that a block or a component of a device is also to be understood as a corresponding method step or as a feature of a method step. Similarly, aspects described in connection with or as a method step also constitute a description of a corresponding block or detail or feature of a corresponding device.

The embodiments described above are merely illustrative of the principles of the present invention. It is understood that modifications and variations to the arrangements and details described herein will occur to those skilled in the art. Therefore, it is intended that the invention be limited only by the scope of the following claims and not by the specific details presented in the description and explanation of the embodiments herein.

reference list

20

antenna

22

radiator

24

radiator elements

25

electrical connection

26

face

28

first entry point

30

second feed point

32

arrows

34

signal line

36

electrical circuit

38

arrows

40

arrow

Claims (10)

Antenna (20) with the following features: a first and a second radiator (22a, 22b), which are each designed to emit and/or receive electromagnetic radiation; the first radiator (22a) having N helical radiator elements (24); the first and second radiators (22a, 22b) being arranged sequentially, the antenna (20) having a first feed point (28) for a first signal, the first feed point (28) being between the first and second radiators (22a, 22b) and having a first contact (28a) connecting the first radiator (22a) contacting and having a second contact (28b) contacting the second radiator (22); wherein the antenna (20) has a second feed point (30) for a second signal, the second feed point (30) being different from the first feed point (28), the second feed point (30) having N contacts, an n- th contact of the second feed point contacts an nth helical radiating element of the N helical radiating elements (24); where N is a natural number greater than or equal to one (as a formula: N > 1) and where n is a running index between 1 and N (as a formula: n=1..N). Antenna (20) according to claim 1 , where the second signal with a phase shift of (n-1) times 360° divided by N (as a formula: $\frac{\left(n-1\right)\cdot 360°}{N}$

is fed into the nth contact of the second feed point. Antenna (20) according to any one of the preceding claims, wherein the first and second radiators (22a, 22b) form a dipole when the first signal is fed into the first feed point (28), which emits the first signal in a vertically polarized manner and or wherein the first radiator (22a) forms a radiator when the second signal is fed into the second feed point (30), which emits the second signal in a circularly polarized manner. The antenna (20) of any preceding claim, wherein the N helical radiating elements (24) form a perimeter of the first radiator (22a), a first signal line (34a) carrying the first signal passing through a cavity within the perimeter of the first radiator (34) is passed through in order to contact the first feed point (28). The antenna (20) of any preceding claim, wherein the N helical radiating elements (24) form a perimeter of the first radiator (22a), a second signal line (34b) carrying the second signal entering a cavity within the perimeter of the first radiator is introduced in order to contact the second feed point (30). Antenna (20) according to one of the preceding claims, wherein the N helical radiating elements (24) form an outer boundary of the first radiator (22a), so that the first radiator (22a) forms a hollow body, the second feed point (30) in the Hollow body of the first radiator (22a) is arranged. Antenna (20) according to one of the preceding claims, wherein the N-helical radiating elements (24) each have a plurality of parallel line strips, the first line strip being connected directly to the second line strip of an adjacent radiating element of the N-helical radiating elements (24). , wherein a distance between the first and the second line band of the same radiating element is smaller than the distance between the first and the second line band of two adjacent radiating elements. Antenna (20) according to claim 7 , wherein the second conductor strips are connected to each other to form the first contact (28a) of the first radiator (22a) for the first feed point (28). Antenna (20) according to claim 7 or 8th , wherein the nth contact of the second feed point (30) contacts the first conduction band of the nth helical radiating element. Method for antenna (20) for producing an antenna (20) with the following steps: - Providing a first and a second radiator (22a, 22b), each designed to emit and/or receive electromagnetic radiation, the first radiator (22a) having N helical radiator elements (24), the first and second radiators (22a, 22b) are arranged sequentially; - Arranging a first feed point (28) of the antenna (20) for a first signal such that the first feed point (28) lies between the first and the second radiator (22a, 22b) and has a first contact (28a) which contacts the first radiator (22a) and has a second contact (28b) which contacts the second radiator (22b); - Arranging a second feed point of the antenna (20) for a second signal such that the second feed point (30) differs from the first feed point (28), the second feed point (30) having N contacts, with an nth contact of the second feed point (30) contacts an nth helical radiating element of the N helical radiating elements (24), where N is a natural number greater than or equal to one (as a formula: N≥1) and where n is a running index between 1 and N (as Formula: n=1..N).

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