CN108183293A - Plane micro-strip duplexer - Google Patents

Abstract

The invention provides a planar microstrip duplexer, which includes a microstrip circuit and a double-sided copper-clad dielectric board. The front side of the double-sided copper-clad dielectric board is provided with a microstrip circuit, and the back is a copper-clad grounding board. The microstrip The circuit includes an input terminal T-joint, a high-pass filter, a low-pass filter and two output ports, the high-pass filter and the low-pass filter are microstrip stub structures, one end of which is transformed by a quarter impedance The lines are connected in parallel to the T-shaped connector at the input end, and the other ends of the high-pass filter and the low-pass filter are respectively connected to an output port. The stubs of the high-pass filter can be connected to the copper-clad grounding plate with solder through the grounding holes, and become short-circuit terminals after connection to introduce magnetic coupling. The planar microstrip duplexer of the present invention has many advantages such as simple structure, light weight, small volume, small in-band insertion loss, convenient tuning, and low manufacturing cost.

Description

planar microstrip duplexer

technical field

The invention relates to the technical field of radio frequency communication, in particular to a planar microstrip duplexer.

Background technique

A duplexer is an essential device for communication system equipment. With the increasing shortage of frequency resources in wireless communication systems, the requirements for performance indicators of duplexers are also getting higher and higher. Reducing the size and cost of the duplexer is very important for reducing the cost of the entire communication system. A new duplexer with high selectivity, high isolation, miniaturization, and low cost is an urgent demand in the market, and it is also an inevitable trend in the development of duplexers.

At present, duplexers are mainly used in microwave and millimeter wave circuit systems to achieve the purpose of transmitting and receiving duplex channels and frequency band duplex communications. The main design of the duplexer includes the design of the filter, and according to the implementation of the filter, it can be divided into: waveguide structure, coaxial structure, and microstrip structure duplexer. The waveguide cavity and coaxial structure are characterized by large power capacity, high quality factor, and low insertion loss, but these structures have narrow operating frequency bands (only a few percent to tens of percent of the relative bandwidth) and large volume. It cannot be used in some occasions with weight and volume restrictions. A duplexer implemented with a planar microstrip structure is generally small in size, light in weight, and easy to tune. Therefore, a planar duplexer is still widely used in microwave and millimeter wave circuits as a convenient structure.

Contents of the invention

The object of the present invention is to provide a planar microstrip duplexer applied to a transceiver system, aiming to solve the problems of large volume, complex structure, and large in-band insertion loss existing in existing planar microstrip duplexer products.

The technical solution to realize the object of the present invention is: a planar microstrip duplexer, including a microstrip circuit and a double-sided copper-clad dielectric board, the front of the double-sided copper-clad dielectric board is provided with a microstrip circuit, and the back is a copper-clad connection. Floor, the microstrip circuit includes an input terminal T-connector, a high-pass filter, a low-pass filter and two output ports, the input terminal of the high-pass filter is connected to the input terminal T-connector, and the output terminal of the high-pass filter is connected to an output port, the input end of the low-pass filter is connected to the T-shaped connector of the input end, and the output end of the low-pass filter is connected to another output port.

Both the input T-joint and the two output ports adopt 50 ohm impedance matching microstrip lines, and grounding areas are respectively set at a distance of 3 mm from the input T-joint and 3 mm from the output port, so as to facilitate the input and output of the connector shell Ground to ensure the performance of the duplexer.

The high-pass filter is composed of four stubs. The stubs are connected to the copper-clad grounding plate of the double-sided copper-clad dielectric board by soldering through the grounding hole, and become short-circuit terminals to introduce magnetic coupling after connection.

Compared with the prior art, the present invention has the following remarkable advantages: (1) It adopts microstrip line structure, which is convenient for tuning, and the dielectric constant of the dielectric plate is 3.3, which effectively reduces the volume of the duplexer and realizes miniaturization; (2) adopts The high-pass filter and low-pass filter are designed in the form of microstrip stubs, which reduces the insertion loss during signal transmission; (3) The stubs of the high-pass filter are grounded through the ground hole to introduce magnetic coupling.

Description of drawings

FIG. 1 is a schematic structural diagram of a planar microstrip duplexer of the present invention.

Fig. 2 is a schematic diagram of the layout of the planar microstrip duplexer of the present invention, wherein (a) is the front side, and (b) is the back side.

Fig. 3 is a simulation result diagram of in-band insertion loss of the planar microstrip duplexer of the present invention.

Fig. 4 is a simulation result diagram of the return loss at the input port of the planar microstrip duplexer of the present invention.

Fig. 5 is a simulation result diagram of the return loss of two output ports of the planar microstrip duplexer of the present invention.

Fig. 6 is a diagram of the simulation results of the 2-port and 3-port isolation of the planar microstrip duplexer of the present invention.

Detailed ways

The technical solution of the present invention will be further described in detail below in conjunction with the accompanying drawings.

Combining Figures 1 and 2, a planar microstrip duplexer includes a microstrip circuit and a double-sided copper-clad dielectric board. The front side of the double-sided copper-clad dielectric board is provided with a microstrip circuit, and the back is a copper-clad grounding board. The microstrip circuit includes an input terminal T-connector, a high-pass filter, a low-pass filter and two output ports, the input terminal of the high-pass filter is connected to the input terminal T-connector, the output terminal of the high-pass filter is connected to an output port, and the low-pass filter is connected to an output port. The input end of the pass filter is connected to the T-shaped connector of the input end, and the output end of the low pass filter is connected to another output port.

Both the input T-joint and the two output ports adopt 50 ohm impedance matching microstrip lines, and grounding areas are respectively set at a distance of 3 mm from the input T-joint and 3 mm from the output port, so as to facilitate the input and output of the connector shell Ground to ensure the performance of the duplexer.

The lengths of the longitudinal branches of the T-joint at the input end are respectively and 50 ohm impedance matched microstrip line, where is the center frequency of the frequency band used by the low-pass filter, Center frequency of the frequency band used by the high-pass filter. In order to prevent the two filters from influencing each other, after simulation optimization 2.9mm, is 5.2mm.

Both the high-pass filter and the low-pass filter are microstrip stub structures, and Richard transform and Koloda rule are used to reduce the insertion loss of the duplexer. At the same time, the structure is compact and reduces the duplex tool volume.

The high-pass filter is composed of four stubs. The stubs are connected to the copper-clad grounding plate of the double-sided copper-clad dielectric board by soldering through the grounding hole, and become short-circuit terminals to introduce magnetic coupling after connection.

The double-sided copper-clad dielectric board adopts the Rogers4533 board with a dielectric constant of 3.3 and a thickness of 0.508 mm, which also reduces the size of the duplexer.

Example 1

As shown in Figure 1, the planar microstrip duplexer of the present invention comprises a microstrip circuit and a double-sided copper-clad dielectric board, the front of the double-sided copper-clad dielectric board is provided with a microstrip circuit, and the back side is a copper-clad grounding board, so The microstrip circuit includes an input T-shaped joint, a high-pass filter, a low-pass filter and two output ports. The high-pass filter and the low-pass filter are all microstrip stub structures, and one end passes through a quarter An impedance transformation line is connected in parallel to the T-shaped connector at the input end, and the other ends of the high-pass filter and the low-pass filter are respectively connected to an output port.

As shown in Figure 2, the T-shaped joint at the input end has a transverse branch of a 50-ohm open-circuit microstrip line, and the external signal is input through the connector. The two output ports are 50 ohm open-circuit microstrip lines, and output signals through the connector. The stubs of the high-pass filter can be connected to the copper-clad grounding plate with solder through the grounding holes, and become short-circuit terminals after connection to introduce magnetic coupling.

As shown in Figure 3, the frequency band used by the high-pass filter in the planar microstrip duplexer is 5.6GHz-6GHz, the in-band insertion loss is less than -0.5dB, and the frequency band used by the low-pass filter is 2.2GHz-2.6GHz , The in-band insertion loss is less than -0.5dB.

As shown in Figure 4, the return loss of the input port port1 is better than -14dB.

As shown in FIG. 5 , the VSWR of the return loss of the output port port2 of the high-pass filter is better than -16dB, and the VSWR of the return loss of port3 of the output port of the low-pass filter is better than -14dB.

As shown in Figure 6, the isolation between port2 and port3 is greater than 38dB.

Claims (7)

1. a kind of plane micro-strip duplexer, it is characterised in that：Including microstrip circuit and double-sided copper-clad dielectric-slab, double-sided copper-clad medium The front of plate is equipped with microstrip circuit, and the back side includes input terminal T connector, high-pass filtering to cover copper earth plate, the microstrip circuit Device, low-pass filter and two output ports, high-pass filter input termination input terminal T connector, high-pass filter it is defeated Go out one output port of termination, the input of low-pass filter terminates input terminal T connector, and the output termination of low-pass filter is another A output port.

2. plane micro-strip duplexer according to claim 1, it is characterised in that：The input terminal T connector and two it is defeated Exit port is using 50 ohms impedance match microstrip lines, at the T connector 3mm of distance input end and apart from output port 3mm Place, is respectively provided with ground area, is grounded convenient for input and output connector housings, ensures the performance of duplexer.

3. plane micro-strip duplexer according to claim 1, it is characterised in that：The input terminal T connector longitudinal direction minor matters Length be respectivelyWith50 ohms impedance match microstrip lines, whereinFrequency range is used by low-pass filter Centre frequency,The centre frequency of frequency range is used by high-pass filter.

4. plane micro-strip duplexer according to claim 3, it is characterised in that：It is describedFor 2.89mm,For 5.2mm.

5. plane micro-strip duplexer according to claim 1, it is characterised in that：The high-pass filter and low-pass filter It is microstrip stubs structure, employs Richard's transformation and Ke Luoda rules, reduces the insertion loss of duplexer, while this It is compact-sized, reduce duplexer volume.

6. plane micro-strip duplexer according to claim 1 or 5, it is characterised in that：The high-pass filter is short by four Transversal is formed, and stub is connect with the copper earth plate that covers of double-sided copper-clad dielectric-slab by ground hole scolding tin, become after connection Short-circuit end introduces magnetic coupling.

7. plane micro-strip duplexer according to claim 1, it is characterised in that：The double-sided copper-clad dielectric-slab uses dielectric The Rogers4533 planks that constant is 3.3, thickness is 0.508mm.