Antenna unit and method for transmitting and receiving signals thereofTechnical Field
The present invention relates to the field of antennas, and in particular, to an antenna unit and a method for transmitting and receiving signals thereof.
Background
In full duplex radios with fixed frequency offsets, a diplexer is typically required to achieve full duplex operation. However, conventional diplexers are typically made of ceramic filters, which are bulky and provide limited isolation. As the size of communication terminals becomes smaller, the size and significant cost of conventional diplexers are issues that must be addressed.
Fig. 3 depicts the operation of a diplexer that provides minimal insertion loss within a desired passband, sufficient isolation between Tx and Rx signals, and sufficient attenuation outside the desired passband. The illustrated configuration requires only one antenna for transmission and reception. However, the use of a single antenna has certain drawbacks. In particular, the antenna must be broadband, covering the Tx and Rx frequencies. Therefore, the antenna gain is low and VSWR (voltage standing wave ratio) performance is poor. In addition, a single antenna requires a duplexer, which, as described above, takes up space and is expensive.
Disclosure of Invention
The technical problem addressed by the present invention is to provide an antenna unit that can provide full duplex operation in the case of a diplexer.
The technical scheme adopted for solving the technical problems is as follows: an antenna unit includes a transmitting antenna, a receiving antenna, and an isolation circuit disposed between the transmitting antenna and the receiving antenna for isolating a transmitting antenna signal from the receiving antenna.
Further is: the device further comprises a first directional coupler and a second directional coupler, wherein the first directional coupler is arranged between the transmitting antenna and the isolation circuit, and the second directional coupler is arranged between the receiving antenna and the isolation circuit;
the first and second directional couplers are used to couple the transmit antenna and the receive antenna, respectively, to the isolation circuit, the first and second directional couplers couple signal energy of the transmit antenna and feed energy to the receive antenna through the isolation circuit.
Further is: the isolation circuit includes a phase adjustment module that receives energy from the transmit side coupler, the phase adjustment module for adjusting a phase of a signal.
Further is: the isolation circuit further includes an amplitude adjustment module coupled to the phase adjustment module, the amplitude adjustment module for adjusting the amplitude of the signal.
Further is: the transmit antenna and the receive antenna are arranged collinearly in a single sleeve or housing.
Further is: one of the transmitting antenna and the receiving antenna is disposed in the housing, and the other is disposed outside the housing.
The invention also discloses a method for transmitting and receiving signals of the antenna unit, which comprises the following steps:
the receiving antenna receives signals and the transmitting antenna transmits signals;
the first directional coupler samples a small portion of the transmit antenna signal, which is delayed and attenuated by the second directional coupler and directed to the receive antenna after passing through the isolation circuit, such that the transmit antenna signal coupled in from the receive antenna will be cancelled by the transmit signal fed through the second directional coupler, achieving isolation of the receive antenna and the transmit antenna.
Further is: the sampling signal passing through the isolation circuit is subjected to phase adjustment and amplitude adjustment.
The beneficial effects of the invention are as follows: the invention provides for isolating the transmitted and received signals and providing sufficient attenuation outside the desired frequency band by providing an isolation circuit between the antennas through a receive antenna and a separate transmit antenna. The dual antenna structure can eliminate the conventional duplexer for the duplex operation. Also, in this case, the layout minimizes the occupied space on the PCB while reducing the manufacturing cost.
Drawings
Fig. 1 is a schematic diagram of a duplex antenna without a duplexer according to the present invention.
Fig. 2 is a schematic diagram of another structure of a duplexer-less duplex antenna according to the invention.
Fig. 3 shows a conventional operation of the duplexer
Marked in the figure as: the antenna system comprises a receiving antenna 12, a transmitting antenna 14, a second directional coupler 18, a first directional coupler 20, an isolation circuit 22, a transmission line 23, an attenuator 24 and a housing 25.
Detailed Description
In order that the above objects, features and advantages of the invention will be readily understood, a more particular description of the invention will be rendered by reference to the appended drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. The present invention may be embodied in many other forms than described herein and similarly modified by those skilled in the art without departing from the spirit of the invention, whereby the invention is not limited to the specific embodiments disclosed below.
Embodiments of the present application disclose an antenna unit comprising a transmit antenna 14, a receive antenna 12, and an isolation circuit 22, the isolation circuit 22 being disposed between the transmit antenna 14 and the receive antenna 12, the isolation circuit 22 being configured to isolate a transmit antenna 14 signal from the receive antenna 12.
Specifically, the antenna further comprises a first directional coupler 20 and a second directional coupler 18, wherein the first directional coupler 20 is arranged between the transmitting antenna 14 and the isolation circuit 22, and the second directional coupler 18 is arranged between the receiving antenna 12 and the isolation circuit 22;
the first and second directional couplers 20 and 18 are used to couple the transmit antenna 14 and the receive antenna 12, respectively, to the isolation circuit 22, the first and second directional couplers 20 and 18 couple signal energy of the transmit antenna and feed energy to the receive antenna 12 through the isolation circuit 22.
Specifically, the isolation circuit 22 includes a phase adjustment module that receives energy from the transmit side coupler, the phase adjustment module configured to adjust the phase of the signal, and the isolation circuit 22 further includes an amplitude adjustment module coupled to the phase adjustment module, the amplitude adjustment module configured to adjust the amplitude of the signal.
In the above-described structure, the first directional coupler 20 and the second directional coupler 18 may be printed on a printed wiring board, and the isolation circuit is constituted by a transmission line 23 and an attenuator 24 on the printed wiring board, receives the signal from the first directional coupler 20 on the transmitting antenna side, and adjusts the phase and amplitude of the signal by means of the lengths of the attenuator 24 and the transmission line 23. For a fixed antenna assembly, the signal values will remain consistent and the line length may be set fixed. Line length calculation of isolation circuit 22 is based on measurements of the phase and amplitude of the signal received by receive antenna 12 using known principles, and in an ideal case the signal energy sampled from transmit antenna 14 and directed to receive antenna 12 should exactly cancel the signal energy received by receive antenna 12 from transmit antenna 14. To achieve the desired isolation between the transmit antenna 14 and the receive antenna 12, the mathematical principles described above are well known to those of ordinary skill in the art and are not repeated here.
In particular, a narrowband antenna may be selected for use in the present application, which results in better matching between the transceiver and the antenna (the receive band and the transmit band are narrower than the combination of the two). Furthermore, due to the large frequency offset between the two antennas (minimum 10 MHz) this will result in a natural isolation of at least 20 dB, so the isolation circuit 22 need only provide an additional 20 dB to achieve effective isolation.
According to the structure of the present invention, a conventional duplexer can be eliminated so as to couple less space consumption and less expensive isolation circuits 22 between the separate transmitting antennas and receiving antennas.
As shown in fig. 2, one embodiment is: the transmit antenna 14 and the receive antenna 12 are arranged co-linearly in a single sleeve or housing 25.
Alternatively, one of the transmitting antenna 14 and the receiving antenna 12 is disposed in the housing, and the other is disposed outside the housing. I.e. one of the antennas may be arranged in an antenna housing, such as a conventional whip antenna, and the other antenna may be connected to the communication device housing.
The invention also discloses a method for transmitting and receiving signals of the antenna unit, which comprises the following steps:
the receiving antenna 12 receives signals, and the transmitting antenna 14 transmits signals;
the first directional coupler 20 samples a small portion of the signal from the transmit antenna 14, which is delayed and attenuated by the second directional coupler 18 and directed to the receive antenna 12 after passing through the isolation circuit 22 such that the signal from the transmit antenna 14 coupled in from the receive antenna 12 will be cancelled by the transmit signal fed through the second directional coupler 18, effecting isolation of the receive antenna 12 from the transmit antenna 14.
Wherein the sampled signal passing through the isolation circuit 22 is phase-adjusted and amplitude-adjusted.
The invention provides for isolating the transmitted and received signals and providing sufficient attenuation outside the desired frequency band by providing an isolation circuit between the antennas through a receive antenna and a separate transmit antenna. The dual antenna structure can eliminate the conventional duplexer for the duplex operation. Also, in this case, the layout minimizes the occupied space on the PCB while reducing the manufacturing cost.
While the foregoing is directed to embodiments of the present invention, other and further details of the invention may be had by the present invention, it should be understood that the foregoing description is merely illustrative of the present invention and that no limitations are intended to the scope of the invention, except insofar as modifications, equivalents, improvements or modifications are within the spirit and principles of the invention.