Patent Application
20120146866
This application claims priority to Taiwan Application Serial Number 099143787, filed Dec. 14, 2010, which is herein incorporated by reference.
1. Technical Field
The present invention relates generally to a communication device, and more particularly to a wireless communication antenna device.
2. Description of Related Art
With a rapid development of electronic technology, wireless communication has become a main medium for signal transmission. There are different types of antennas utilized in wireless communication systems, for example, dipole antenna, monopole antenna, microstrip antenna, horn antenna, dish antenna, etc. The dish antenna has the advantages of high directivity and high gain, so the dish antenna has been widely used in satellite communication and terrestrial microwave communication systems.
In view of the radiation efficiency of the dish antenna system, the horn antenna (e.g. elliptical horn antenna) is therefore a better type of the feed antenna in the dish antenna system.
In practice, the dish antenna system further includes a polarizer connected with the horn antenna used as the feed antenna. The polarizer can be a conventional 90-degree polarizer, in which the 90-degree polarizer is configured for dividing a linearly polarized wireless electromagnetic wave into two components having a 90-degree phase difference therebetween and being orthogonal with each other, and then a circularly polarized wireless electromagnetic wave is formed. That is, the original linearly polarized wireless electromagnetic wave can be translated to the circularly polarized wireless electromagnetic wave by the 90-degree polarizer. Similarly, the 90-degree polarizer can translate the polarized wireless electromagnetic wave from circular polarization to linear polarization as well.
Besides, when the horn antenna, which has a non-equilateral transverse opening, transmits or receives the circularly polarized wireless electromagnetic wave, a vertical electric field component and a horizontal electric field component being orthogonal with each other separately have different phase velocities, such that the vertical electric field component and the horizontal electric field component have a phase difference therebetween. Thus, the connection and operation of the 90-degree polarizer with the horn antenna will not yield an optimum propagation performance of the electromagnetic wave and translation performance between linear polarization and circular polarization.
Therefore, there is a need providing a wireless communication antenna device for optimizing the propagation performance and the translation performance of the polarized wireless electromagnetic wave.
The present invention provides a waveguide having a transverse opening with non-equilateral lengths and/or non-symmetric axes, for compensating a phase difference between a vertical electrical field component and a horizontal electrical field component of a polarized wireless electromagnetic wave propagated within a horn antenna.
One aspect of the present invention provides a wireless communication antenna device including a horn antenna and a waveguide. The horn antenna is used for transmitting or receiving a polarized wireless electromagnetic wave having a first electric field component and a second electric field component, and the first electric field component and the second electric field component are orthogonal with each other. The waveguide is connected to the horn antenna, for propagating the polarized wireless electromagnetic wave, wherein a first opening of the waveguide includes a side corresponding to the first electric field component and another side corresponding to the second electric field component, and a length of the side corresponding to the first electric field component is different from a length of the side corresponding to the second electric field component, such that the first electric field component and the second electric field component have a phase difference therebetween when the polarized wireless electromagnetic wave is propagated in the waveguide.
According to one embodiment of the present invention, the length of the side corresponding to the first electric field component is a first length, and the length of the side corresponding to the second electric field component is a second length, and the first length and the second length are increased or decreased along the direction of propagation of the polarized wireless electromagnetic wave.
According to another embodiment of the present invention, the waveguide has a first lengthwise face and a second lengthwise face connected adjacently to the first lengthwise face. A first included angle is formed between the first lengthwise face and the direction of propagation of the polarized wireless electromagnetic wave, and a second included angle is formed between the second lengthwise face and the direction of propagation of the polarized wireless electromagnetic wave.
According to yet another embodiment of the present invention, a second opening of the waveguide is the same as or different from the first opening of the waveguide.
According to a further embodiment of the present invention, the wireless communication antenna device further includes a polarizer connected with the waveguide, for providing a translation between linear polarization and circular polarization of the polarized wireless electromagnetic wave.
Another aspect of the present invention provides a wireless communication antenna device including a horn antenna and a waveguide. The horn antenna is used for transmitting or receiving a polarized wireless electromagnetic wave having a first electric field component and a second electric field component, and the first electric field component and the second electric field component are orthogonal with each other. The waveguide is connected to the horn antenna, for propagating the polarized wireless electromagnetic wave. A first opening of the waveguide is elliptical, the first opening includes a major axis corresponding to the first electric field component and a minor axis corresponding to the second electric field component, and the major axis is different from the minor axis, such that the first electric field component and the second electric field component have a phase difference therebetween when the wireless polarized wave is propagated in the waveguide.
According to one embodiment of the present invention, the major axis and the minor axis are increased or decreased along the direction of propagation of the polarized wireless electromagnetic wave.
According to another embodiment of the present invention, the waveguide has a major lengthwise face and a minor lengthwise face, a first included angle is formed between the major lengthwise face and the direction of propagation of the polarized wireless electromagnetic wave, and a second included angle is formed between the minor lengthwise face and the direction of propagation of the polarized wireless electromagnetic wave.
According to yet another embodiment of the present invention, a second opening of the waveguide is the same as or different from the first opening of the waveguide.
According to a further embodiment of the present invention, the wireless communication antenna device further includes a polarizer connected with the waveguide, for providing a translation between linear polarization and circular polarization of the polarized wireless electromagnetic wave.
The invention can be more fully understood by reading the following detailed description of the embodiments, with reference made to the accompanying drawings as follows:
Reference will now be made in detail to the present embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.
According to one embodiment of the present invention, a wireless communication antenna device 100 is shown in
A brief principle of the polarized wireless electromagnetic wave propagated in the waveguide 120 will be illustrated below. The electromagnetic wave propagated in the waveguide 120 with different transverse dimensions travels at different phase velocities. If the transverse dimensions of the waveguide 120 are, non-equilateral, the fundamental modes of the electromagnetic wave in the waveguide 120, therefore, have different phase velocities. For example, the phase velocity of TEmn mode in a rectangular waveguide is ω/β, where ω is the angular frequency, β=√{square root over (k2−k2c)} is the propagation constant, k is wave number, kc=√{square root over ((mπ/a)2+(nπ/b)2)}{square root over ((mπ/a)2+(nπ/b)2)} is the cutoff wave number, m and n are integers greater than or equal to zero but not concurrently equal to zero, and a and b are inner dimensions of the waveguide 120. A rectangular waveguide 120 with inner dimensions a and b supports fundamental modes. If a>b, these fundamental modes are TE01 mode and TE10 mode, and both of two propagation modes are orthogonal with each other, and they have respective phase velocities different from each other. If in the beginning TE01 mode and TE10 mode have a phase difference φ0, after these two modes travel a certain distance along the waveguide 120, they experience different amounts of phase change and their phase difference becomes φ0+Δφ1, where Δφ1 depends on the distance they travel. Therefore, by controlling the length of the waveguide 120, arbitrary phase difference between two orthogonal propagation modes of the electromagnetic wave can be generated. Thus, a first electric field component and a second electric field component of the polarized wireless electromagnetic wave, respectively corresponding to the two orthogonal propagation modes mentioned above, are used for illustration in the embodiments of the present invention.
In the embodiment, the waveguide 220 has a first opening 221, and the polarized wireless electromagnetic wave propagated in the waveguide 220 has the first electric field component and the second electric field component, in which the first electric field component and the second electric field component are orthogonal with each other. The first opening 221 of the waveguide 220 includes two sides respectively corresponding to the first and second electric field component, and the two sides respectively corresponding to the first and second electric field component have a first length 231 and a second length 241, respectively, wherein the first length 231 is different from the second length 241, such that the first electric field component and the second electric field component have a phase difference therebetween when the polarized wireless electromagnetic wave is propagated in the waveguide 220. In the embodiment of the present invention, although the first length 231 of the first opening 221 of the waveguide 220 corresponds to (e.g. in parallel to) the first electric field component, the mode characteristic of the first electric field component is controlled by the second length 241. Similarly, the second length 241 of the first opening 221 of the waveguide 220 corresponds to (e.g. in parallel to) the second electric field component, but the mode characteristic of the second electric field component is controlled by the first length 231. The corresponding and the controlling relationships between the lengths of the transverse opening of the waveguide 220 and the mode characteristics are illustrated above, and these features can be applied throughout the embodiments.
In another embodiment of the present invention, the first length 231 and the second length 241 are increased or decreased along the Z-axis (the direction of propagation of the polarized wireless electromagnetic wave). Specifically, the first length 231 of the first opening 221 of the waveguide 220 can be increased or decreased along the −Z direction, and the second length 241 of the first opening 221 of the waveguide 220 can be increased or decreased along the −Z direction, such that the transverse opening area of the waveguide 220 can be increased or decreased along the −Z direction.
For example, the waveguide 220 has a second opening 222 opposite to the first opening 221, and the second opening 222 has adjacently connected two sides having a length 232 and a length 242, respectively. The first length 231 of the first opening 221 can be decreased along the −Z direction, such that the first length 231 of the first opening 221 is greater than the length 232 of the second opening 222, while the second length 241 of the first opening 221 can be decreased along the −Z direction, such that the second length 241 of the first opening 221 is greater than the length 242 of the second opening 222.
In a further embodiment of the present invention, the second opening 222 of the waveguide 220 is different from the first opening 221 of the waveguide 220. For example, when the second opening 222 is different from the first opening 221 of the waveguide 220, that means the transverse opening area of the waveguide 220 will be changed along the Z-axis; that is, the first included angle α is different from the second included angle θ. The shapes of two transverse openings of the waveguide 220 can be demonstrated as follows: the first opening 221 is rectangular and the second opening 222 is square, or the first opening 221 is rectangular and the second opening 222 is another rectangular having different dimensions from the first opening 221. Therefore, the phase velocity of the first electric field component is different from the phase velocity of the second electric field component, when the first electric field component and the second electric field component are propagated in the waveguide 220, and thus the phase difference is formed.
The relationships of the first included angle α and the second included angle θ can be applied to the entire body of the waveguide 220 in the illustration above, and it is not intended to limit the pervious relationships at the first opening 221 or at the second opening 222 without departing from the spirit and scope of the present invention.
On the other hand, a change of the transverse area traveling along the Z-axis between the first opening 221 and the second opening 222 of the waveguide 220 has to meet the relationship between the adjacent lengths of the openings of the waveguide 220 and the cutoff frequency of the propagation modes, because the waveguide 220 having the transverse opening with particular sides and lengths thereof guides the electromagnetic wave with a particular range of frequency and has a particular cutoff frequency. The propagation mode of the electromagnetic wave can be propagated in the waveguide 220 when the propagated frequency is greater than the cutoff frequency. Therefore, the length of the waveguide 220, which ranges from the first length 231 and the second length 241 of the first opening 221 of the waveguide 220 to the first length 232 and the second length 242 of the second opening 222 of the waveguide 220, has to be limited, such that the lengths of the transverse opening of the waveguide 220 have to be greater than the lengths corresponding to the cutoff frequency to avoid that the electromagnetic wave cannot be guided within the waveguide 220.
In the embodiment, the waveguide 420 has a first opening 421, and the polarized wireless electromagnetic wave propagated in the waveguide 420 has the first electric field component and the second electric field component, and the first electric field component and the second electric field component are orthogonal with each other. The first opening 421 of the waveguide 420 includes a major axis 431 corresponding to the first electric field component and a minor axis 441 corresponding to the second electric field component, wherein the major axis 431 is different from the minor axis 441, such that the first electric field component and the second electric field component have a phase difference therebetween when the polarized wireless electromagnetic wave is propagated in the waveguide 420. In the embodiment of the present invention, although the major axis 431 of the first opening 421 of the waveguide 420 corresponds to (e.g. in parallel to) the first electric field component, the mode characteristic of the first electric field component is controlled by the minor axis 441. Similarly, the minor axis 441 of the first opening 421 of the waveguide 420 corresponds to (e.g. in parallel to) the second electric field component, but the mode characteristic of the second electric field component is controlled by the major axis 431. The corresponding and the controlling relationships between the axes of the transverse opening of the waveguide 420 and the mode characteristics are illustrated above, and these features can be applied throughout the embodiments.
In another embodiment of the present invention, the major axis 431 and the minor axis 441 are increased or decreased along the Z-axis (the direction of propagation of the polarized wireless electromagnetic wave). Specifically, the major axis 431 of the first opening 421 of the waveguide 420 can be increased or decreased along the −Z direction, and the minor axis 441 of the first opening 421 of the waveguide 420 can be increased or decreased along the −Z direction, such that the transverse opening area of the waveguide 420 can be increased or decreased along the −Z direction.
For example, the waveguide 420 has a second opening 422 opposite to the first opening 421, and the second opening 422 has a major axis 432 and a minor axis 442, in which the major axis 432 and the minor axis 442 are orthogonal with each other. The major axis 431 of the first opening 421 can be decreased along the −Z direction, such that the major axis 431 of the first opening 421 is greater than the major axis 432 of the second opening 422, while the minor axis 441 of the first opening 421 can be decreased along the −Z direction, such that the minor axis 441 of the first opening 421 is greater than the minor axis 442 of the second opening 422.
In a further embodiment of the present invention, the second opening 422 of the waveguide 420 is different from the first opening 421 of the waveguide 420. For example, when the second opening 422 is different from the first opening 421 of the waveguide 420, that means the transverse opening area of the waveguide 420 will be changed along the Z-axis; that is, the first included angle α is different from the second included angle θ. The shapes of two transverse openings of the waveguide 420 can be demonstrated as follows: the first opening 421 is elliptical and the second opening 422 is circular, or the first opening 421 is elliptical and the second opening 422 is elliptical and having different dimensions from the first opening 421. Therefore, the phase velocity of the first electric field component is different from the phase velocity of the second electric field component, when the first electric field component and the second electric field component are propagated in the waveguide 420, and thus the phase difference is formed.
The relationships of the first included angle α and the second included angle θ can be applied to the entire body of the waveguide 420 in the illustration above, and it is not intended to limit the pervious relationships at the first opening 421 or at the second opening 422 without departing from the spirit and scope of the present invention.
On the other hand, a change of the transverse area traveling along the Z-axis between the first opening 421 and the second opening 422 of the waveguide 420 has to meet the relationship between the orthogonal axes of the openings of the waveguide 420 and the cutoff frequency of the propagation modes, because the waveguide 420 having the transverse opening with particular axes thereof guides the electromagnetic wave with a particular range of frequency and has a particular cutoff frequency. The propagation mode of the electromagnetic wave can be propagated in the waveguide 420 when the propagated frequency is greater than the cutoff frequency. Therefore, the axis of the waveguide 420, which ranges from the major axis 431 and the minor axis 441 of the first opening 421 of the waveguide 420 to the major axis 432 and the minor axis 442 of the second opening 422 of the waveguide 420, has to be limited, such that the axes of the transverse opening of the waveguide 420 have to be greater than the axes corresponding to the cutoff frequency to avoid that the electromagnetic wave cannot be guided within the waveguide 420.
Compared to the prior art, the present invention provides a waveguide having a transverse opening with non-equilateral lengths and/or a non-symmetry axes, such that the first electric field component and the second electric field component which are orthogonal with each other have a phase difference therebetween when the polarized wireless electromagnetic wave is propagated in the waveguide, for compensating the phase difference of the polarized wireless electromagnetic wave propagated in the horn antenna, thus an arbitrary phase difference can be created by controlling the length of the waveguide body for different requirements, such that the phase characteristics of the propagation of the polarized wireless electromagnetic wave and the translation performance between the linear polarization and the circular polarization can be improved.
Although the present invention has been described with reference to a preferred embodiment thereof, this embodiment is not intended to limit the present invention. It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the scope or spirit of the present invention. Therefore, the scope of the present invention shall be defined by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 099143787 | Dec 2010 | TW | national |
