JPH08213835A - Antenna in common use for two frequencies - Google Patents

Abstract

PURPOSE: To provide an antenna in common use for two frequencies with high isolation capable of transmission/reception without any addition of a large sized and expensive signal isolation means such as a duplexer. CONSTITUTION: A 1st circular patch antenna 14 is provided on an upper major surface of a 1st dielectric layer 1 having a ground conductor 2 on a lower major surface, a 2nd dielectric layer 5 is arranged on the 1st dielectric layer 1, and a 2nd circular patch antenna 6 is formed concentrically to the 1st circular patch antenna 14 on the upper major surface. Then a filter element 16 is provided in the 1st dielectric layer 1 and the circular patch antenna 6 is fed via the filter element 16.

Description

Detailed Description of the Invention

[0002]

FIELD OF THE INVENTION The present invention relates to an antenna for communication equipment,
In particular, the present invention relates to a dual frequency antenna that can be mounted on an aircraft or the like.

[0003]

2. Description of the Related Art In the field of mobile communication, dual-frequency dual-purpose antennas for both transmission and reception have been used. 4 and 5 are a plan view and a sectional view taken along the line AA ', respectively, showing the configuration of a conventional dual frequency antenna. As shown in the figure,
The ground conductor 2 is arranged on the lower main surface of the dielectric substrate 1, and the ring patch antenna 3 formed of a ring-shaped radiation conductor is arranged on the upper main surface in parallel with the ground conductor 2. In addition, the inner circumference of the circular patch antenna 3 and the ground conductor 2 are formed by the cylindrical conductor 4 having a diameter equal to the inner diameter of the radiation conductor 3.
And are electrically connected to. Further, a second dielectric substrate 5 is arranged on the first dielectric substrate 1, and a circular patch antenna composed of circular radiation conductors arranged concentrically with the circular patch antenna 3 on the upper surface thereof. 6 are arranged in parallel with the ground conductor 2. The center conductors 9 and 10 of the power feeding coaxial cables 7 and 8 are connected to the two patch antennas 3 and 6, respectively, and the power feeding coaxials that surround the center conductors 9 and 10 in a cylindrical shape via an insulating member. The ground conductor portions of the cables 7 and 8 are both electrically connected to the ground conductor 2 of the first dielectric substrate 1. The center conductor 9 is electrically connected to the circular patch antenna 3 (a white circle in FIG. 4) via a feeder line 11 penetrating the first dielectric substrate 1, and the central conductor 10 is a circular patch antenna. Feed line 12 that passes through the inside of the inner diameter of 3 and passes through the two dielectric substrates
Are electrically connected (black circles in FIG. 4) to the circular patch antenna 6 at a position displaced from the center thereof by a predetermined distance.
Incidentally, these connection points are generally called feeding points to the antenna. With the above configuration, the circular patch antenna 3 is connected to the feeding coaxial cable 8 via the feeding coaxial cable 7.
The circular patch antenna 6 can be excited via the. Here, by making the resonance frequency of the circular patch antenna 3 different from the resonance frequency of the circular patch antenna 6 and using each as the transmission frequency and the reception frequency, the above antenna can be used as a dual frequency antenna. As is well known, the resonance frequency of a circular (annular) patch antenna is determined by the diameter and thickness of the radiating conductor and the permittivity of the dielectric substrate, so it is necessary to design it appropriately according to the required resonance frequency. Good.

Further, as shown in FIG. 6, in such a dual frequency antenna, the distance from the center of the circular patch antenna 3 to the connection point is the same as that of the feeding coaxial cable 7 but at a different position (white in the figure). In addition, at least one feeding coaxial cable is additionally connected (black square in the figure) at different positions where the distance from the center of the circular patch antenna 6 to the connection point is the same as the feeding coaxial cable 8 but different. A multi-point feed type dual frequency antenna has been proposed. For example, as disclosed in Japanese Utility Model Laid-Open Publication No. 2-35514, circularly polarized waves can be generated by shifting the phases of power feeding to these power feeding coaxial cables, and a transmitting antenna and a receiving antenna can be generated. Circular polarization of the same direction,
For example, by using left-handed circularly polarized wave, isolation of about 30 dB can be established between the transmitting antenna and the receiving antenna. It is known that circularly polarized waves can be generated even at one feeding point by forming a cutout in the outer peripheral portion of a circular or annular radiation conductor.

However, when the dual-frequency antenna having the above-mentioned structure is used as an antenna for mobile communication over a long distance, it is highly possible that a received signal is attenuated in a long transmission line and becomes extremely weak. Therefore, it has become necessary to increase the isolation between transmission and reception to limit the phenomenon of the signal sneaking from the transmission antenna to the reception antenna. To solve this, Japanese Patent Laid-Open No. 5-175
An isolation improving means as disclosed in Japanese Patent No. 727 has been proposed. For example, as shown in FIG. 7, in the dual frequency antenna as described above, the feeding point of the circular patch antenna 6 and the feeding point of the circular patch antenna 3 are set with the center of the circular (annular) patch antenna as a reference. By changing the relative angle Θr with, the isolation between the circular patch antenna 6 and the circular patch antenna 3 changes, and by selecting the relative angle Θr to the optimum value, the isolation of about 55 dB at maximum can be obtained. .

However, the isolation required for a dual frequency antenna is higher, and it is the current situation that it is not possible to deal with the above-mentioned method alone. In reality, as shown in FIG. Duplexer 1 composed of stripline etc. to separate transmission and reception
Since the signal separating means such as 3 must be provided in the communication device, and it is expensive and has a large shape, it is not suitable for downsizing and cost reduction of the communication device.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a dual frequency shared antenna having high isolation which can be transmitted and received without adding an expensive and large-sized signal separating means such as a duplexer.

[0008]

SUMMARY OF THE INVENTION A first circular patch antenna is provided on an upper main surface of a first dielectric layer having a ground conductor on a lower main surface, and a second dielectric is provided on the first dielectric layer. In a dual frequency antenna in which a layer is provided and a second circular patch antenna is formed concentrically with the first circular patch antenna on the upper main surface of the layer, a filter element is provided in the first dielectric layer. The circular patch antenna is configured to be fed through the filter element.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the illustrated embodiments. 1 and 2 are a plan view and a BB ′ cross-sectional view showing the configuration of an embodiment of a dual frequency antenna according to the present invention. As shown in the figure, the ground conductor 2 is formed on the lower main surface of the first dielectric substrate 1, and the first circular patch antenna 14 made of a circular radiation conductor is formed on the upper main surface. Are arranged in parallel with the ground conductor 2. Further, the first circular patch antenna 14 and the ground conductor 2 are electrically connected by the cylindrical conductor 15 having the same center as the first circular patch antenna 14 and having an appropriate diameter.
Further, a second dielectric substrate 5 is arranged on the first dielectric substrate 1, and a second circular radiating conductor arranged concentrically with the first circular patch antenna 14 is arranged on the second dielectric substrate 5. Two circular patch antennas 6 are formed so as to be arranged in parallel with the ground conductor 2. In this dual frequency transmission / reception antenna, each patch antenna is provided with a plurality of feeding points (two feeding points for each circular patch antenna in FIG. 1) at the same distance from the center but at different positions to feed signals with different phases. By doing so, the circular polarizations of the transmitting antenna and the receiving antenna are configured to be in the same direction as each other, for example, left-hand circular polarization, and then the first circular patch antenna 14 and the second circular patch antenna 14 are arranged.
As described above, if the relative angle Θr of the circular patch antenna 6 is appropriately selected, isolation of about 55 dB can be established between the transmitting antenna and the receiving antenna without the filter 16.

Further, in the portion surrounded by the cylindrical conductor 15, two dielectric filters 16 and 16 are enclosed by a filler 17 having an insulating property. For example,
The center conductor 10 of one of the feeding coaxial cables 8 that feeds the second circular patch antenna 6 is fed from the center by a feed line 12 penetrating the second dielectric substrate 5 through one of the dielectric filters 16. It is electrically connected to the second circular patch antenna 6 at a position displaced in the circumferential direction. A through hole is provided at an appropriate position of the first circular patch antenna 14 so that the feeder 12 and the first circular patch antenna 14 are not electrically connected. On the other hand, the first circular patch antenna 1
The center conductor 9 of the feeding coaxial cable 7 for feeding 4
Is electrically connected to the first circular patch antenna 14 at a position deviated in the circumferential direction from the center of the first circular patch antenna 14 via a feeder line 11 penetrating the first dielectric substrate 1. It In this example, the second circular patch antenna 6 is used as a reception frequency and the first circular patch antenna 14 is used as a transmission frequency. In the multi-feed type circular patch antenna, other feeding coaxial cables are similarly connected to the circular patch antenna, and a dielectric filter is provided at each feeding point of the receiving side antenna. The grounding conductors of the power feeding coaxial cable are all the first circular patch antenna 14
It is electrically connected to the ground conductor 2 on the lower surface.

As described above, by inserting the dielectric filter 16, the effect of isolation is increased, and a larger isolation can be obtained between transmission and reception. In addition, since the dielectric filter is arranged close to the feeding point of the patch antenna, the wiring distance from the feeding point is significantly shortened, and the transmission loss can be limited.

In general, a dielectric filter has a ground electrode attached to the periphery of a prismatic dielectric (for example, ceramic), and a hole penetrating therethrough is formed at the center of the prismatic dielectric. A cylindrical electrode is attached to its inner surface. FIG. 3A is a view showing an example in which three dielectric filters are connected in parallel via capacitors to form one filter unit. In the dielectric filter shown in FIG. 4A, the outer dimension of one dielectric is 4
mm × 4 mm × 5 mm, and the dielectric constant εr of the dielectric is 9
It is a filter characteristic figure calculated | required by the simulation about the case of 0-100. A simulation was performed on the isolation when the dielectric filter shown in FIG. 3 was used as the dielectric filter 16 of the dual frequency antenna of FIGS. For example, considering a case where the invention is applied to a dual frequency antenna of a communication device having a reception band of 1525 to 1559 MHz and a transmission band of 1626.5 to 1660.5 MHz, which is generally used in the field of aeronautical satellite communication, FIG.
As is clear from (b), the attenuation characteristic of the filter is ensured to be about 30 dB between these two frequency bands, so that a total isolation of about 85 dB can be obtained. For example, in the field of aeronautical satellite communication, isolation between transmission and reception of approximately 90 dB is required, but by optimizing the dielectric filter and slightly increasing the attenuation of the filter, this standard can be satisfied without a duplexer. A frequency shared antenna can be realized.

Although the present invention has been described with reference to the dual frequency antenna using the circular patch antenna formed on the dielectric substrate as an example, the present invention is not limited to these embodiments, and is omitted. It may be a patch antenna composed of a circular (for example, regular polygon) radiation conductor, or
It may be configured by a ring-shaped patch antenna. Further, the dielectric substrate is not necessarily used, and it is sufficient that the patch antenna and the ground conductor are provided with a dielectric layer inserted or filled so as to be substantially parallel to each other. Further, although the dielectric filter is arranged in the first dielectric substrate in the embodiment, it may be arranged not only in the first dielectric substrate but also in the second dielectric substrate or both of them. Any filter other than, for example, a piezoelectric filter or the like may be used. Furthermore, although the case of using it for aeronautical satellite communication has been described, it goes without saying that it can be applied to an antenna in the field of performing communication using a high frequency band.

[0014]

As described above, according to the present invention, by disposing the filter inside the dielectric substrate or the dielectric layer of the dual frequency antenna, the isolation between the transmission and the reception can be greatly improved only by the antenna. be able to. Especially when it is used as a mobile antenna for satellite communication that requires a transmission / reception isolation of about 90 dB or more, the specifications of the bandpass filter of the duplexer used for separation of transmission and reception are relaxed, or the duplexer itself. Can be eliminated, and the cost of the antenna feeding system can be reduced, and a significant effect can be obtained in achieving miniaturization indispensable for mobile communication equipment.

[0015]

[Brief description of drawings]

FIG. 1 is a top view of a dual frequency antenna according to the present invention.

FIG. 2 is a BB ′ cross-sectional view of the dual frequency antenna according to the present invention.

3A and 3B are an external view of a dielectric filter and a filter characteristic diagram of the dielectric filter obtained by simulation, respectively.

FIG. 4 is a top view of a conventional dual frequency antenna.

FIG. 5 is a sectional view taken along the line AA ′ of the conventional dual-frequency antenna.

FIG. 6 is a top view of a conventional dual frequency antenna.

FIG. 7 is a top view of a conventional dual frequency antenna.

FIG. 8 is a block diagram of a transmitter / receiver using a conventional dual frequency antenna.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... 1st dielectric substrate 2 ... Ground conductor 3 ... Annular patch antenna 4, 15 ... Cylindrical conductor 5 ... 2nd dielectric substrate 6, 14 ... Circular patch antenna 7, 8 ... Coaxial cable for feeding 9, 10 ... Central conductor 11, 12 ... Feed line 16 ... Dielectric filter 17 ... Filler

Claims (1)

[Claims] 1. A first circular patch antenna is provided on the upper surface of a first dielectric layer having a ground conductor on the lower surface, and a second dielectric layer is provided on the upper surface of the first circular patch antenna. In a dual frequency antenna in which a second circular patch antenna is arranged concentrically with the first circular patch antenna on the upper surface of a second dielectric layer, in the first or second dielectric layer. A dual frequency antenna, comprising a filter element and feeding power to a circular patch antenna through the filter element. [0001]