CN1909400A - Beam forming and switching method based on regular polyhedron intelligent antenna assembly - Google Patents

Abstract

The present invention provides a smart antenna based on a regular polyhedron for the defects that the antenna array needs to use a phase shifter and a complex PIN switch array caused by the "sector-beam" two-stage structure of the existing three-plane array beam switching smart antenna. Beamforming and handover methods. In this method, the circular antenna array formed by the regular polyhedron is used to decode the instructions sent by the host computer by the logic control circuit, and the decoded signal is sent to the drive circuit, and the drive circuit generates a corresponding drive signal according to the decoded signal to drive the radio frequency switch. The corresponding transmission feeder and the antenna unit connected to it are gated or turned off; the radio frequency signal reaches each gated microstrip antenna unit at the same time, and after coherent superposition, an in-phase beam is formed in the normal direction of the circumscribed circle of the regular polyhedron. The method of the invention does not need a phase shifter or a delay line, and both the array structure and the circuit structure adopt a symmetrical form, thereby solving the inconsistency of beams of the non-structurally symmetrical antenna array and improving the overall performance of the antenna system.

Description

A Beam Forming and Switching Method Based on Regular Polyhedron Smart Antenna Device

technical field

The invention relates to a beam forming and switching method of an intelligent antenna system, in particular to a beam forming and switching method based on a regular polyhedron intelligent antenna device.

Background technique

In wireless communication antenna systems, smart antenna systems are mainly divided into four categories: sectorized antenna systems, beam switching antenna systems, beam forming antenna systems and diversity antenna systems. Among them, the "intelligence" level of the sectorized antenna system and the beam switching antenna system is low, and the ability to increase the user capacity and improve the communication quality of the wireless communication system is limited, but these two systems are low in cost and easy to implement . The "intelligence" level of the beamforming antenna system and the diversity antenna system is relatively high, and it is a hot spot in the field of smart antenna technology research. At present, a large number of adaptive algorithms for smart antennas have been proposed, but due to the complexity of these algorithms and the limitation of hardware processing speed, it is still difficult to find one that can work effectively in harsh environments and make the signal get better. Practical adaptive algorithms for real-time processing. Therefore, people have gradually shifted their attention to the realization of beam-switching smart antennas.

The beam switching antenna system generates multiple narrow beams with different directions within the coverage area, and only selects one beam coverage area for communication at each moment. Wherein, each beam can be generated by a single directional antenna unit (such as a horn mouth antenna), or can be generated by an antenna array composed of multiple antenna units. The "intelligence" of the beam switching smart antenna is mainly reflected in the fact that its beam switching is controlled by the beam selection method. Specifically, in the beam switching system, the beam selection method first determines which beam the user is in, and then switches the switch to The beam with the best reception performance.

If each beam of the beam switching antenna system is generated by an antenna array, it can obtain a much larger array gain than an omnidirectional antenna, thereby improving network coverage and reducing the power of network equipment. In order to use limited antenna elements to generate as many beams as possible, each antenna element will be used to generate different spatial beams, which requires switching control of different antenna elements and controlling their phases according to different beam directions. The switch (PIN) of multiple antenna units forms the switch array of the beam switching system, and the implementation process can be completed at the radio frequency end, or can be placed at the intermediate frequency or baseband, but usually, the beam switching at the radio frequency end is complicated. Lower degree and cost. The two most important performance indicators of RF switches are isolation and insertion loss. Isolation is an index to measure the effectiveness of the switch cut-off, which refers to the ratio between the total signal energy and the leaked signal energy after the switch is turned off. Insertion loss is the transmission loss caused by the physical structure of the switch. Generally, it mainly considers the heat loss when the current passes in the on state. In addition to the above two points, factors such as switching speed (general PIN diodes can reach ms level) and the influence of the switch itself on the signal phase need to be considered when designing the switch array.

The beam switching method of the existing smart antenna device is a three-sided array antenna system based on an equilateral triangle shape. The three-plane array antenna device is composed of three planes, and each plane is a uniform linear microstrip antenna array composed of three antenna units. The antenna array on each plane covers 90 degrees in pitch angle and 120 degrees in azimuth angle. Each antenna array forms three switchable beams in the azimuth sector, each beam width is 40 degrees. Delay lines with different lengths are selected to achieve different phase shifts, and a switch array composed of PIN diodes is used to switch beams, that is, a PIN master switch is used, one input, three outputs to each side of the linear antenna array, each side The antenna array requires a power divider, requiring a total of 39 PIN diodes.

The "sector-beam" structure of the three-sided array antenna device has a forward beam and a side beam. The forward beam refers to the beam (generated by in-phase excitation) perpendicular to the antenna array panel in each sector. The direction beam refers to the other two beams in each sector except the forward beam (generated by non-in-phase excitation). The side beam has strict requirements on the length of the microstrip delay line, but due to the influence of processing accuracy, the phase change of the delay line shows obvious inconsistency, resulting in poor symmetry of the side beam, and the main lobe side The lobe suppression ratio is only about 7dB, which will affect the interference suppression performance of the beam; in addition, the radio frequency switch array used to switch the delay line is also relatively large, requiring the use of many components, resulting in a large insertion loss, which leads to the overall loss of the antenna array. Reduced performance.

Contents of the invention

The present invention aims at the antenna array caused by the two-level structure of "sector-beam" existing in the existing three-plane array beam switching smart antenna, which needs to use phase shifters (that is, delay lines with different lengths), complex PIN switch arrays, and each beam Inconsistency and other defects provide a beam forming and switching method based on a centrosymmetric regular polyhedron, especially a regular polygonal prism smart antenna. This method utilizes the circular antenna array formed by regular polygonal prisms, which solves the inconsistency of beams, reduces the complexity of the antenna system and improves the overall performance of the system.

In order to achieve the above purpose, the present invention is achieved by adopting the following technical solutions.

A beam forming and switching method based on a centrosymmetric regular polyhedron smart antenna device, comprising the following control process:

a) Feed the radio frequency signal from the input port of the power distribution/combiner, according to the position information of the receiver, the upper computer sends a gating command, through the logic control circuit and the driving circuit, the nine microstrip antenna units are strobed by the radio frequency switch Connect the three feeders of the three adjacent antenna units corresponding to the direction of the receiver, and the three adjacent microstrip antenna units that are selected will transmit the radio frequency signal; The feeder connected to the antenna unit; three adjacent microstrip antenna units that are gated form a circular array and form a beam pointing to the receiver;

b) When the position of the receiver changes, the host computer reselects three adjacent microstrip antenna units that need to be selected according to the current channel state information periodically detected, and sends a switching instruction to the logic control circuit board;

c) After the logic control circuit board receives the switching instruction, the CPLD module of the logic control circuit decodes the instruction, and sends the decoding signal to the driving circuit of the driving circuit board, and the driving circuit generates a corresponding drive according to the decoding signal Signal, and send the drive signal to the RF switch, the RF switch selects another group of adjacent three microstrip antenna units through the transmission feeder, and turns off the rest of the antenna units, so as to realize the intelligent switching of the beam.

In the above scheme, the radio frequency signal fed from the input port of the power distribution/combiner arrives at the microstrip antenna units of each gate at the same time, and through coherent superposition, an in-phase beam is formed in the normal direction of the circumscribed circle of the regular polyhedron; Adjacent microstrip antenna units can be reused in the process; the three adjacent microstrip antenna units that are gated form an annular array, and its array factor formula is:

${\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span><span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="j"\; filenames="A20061010448100151.png,A20061010448100181.png"\; state="\{\{state\}\}">j</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}\frac{\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 50</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; c</span>}}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="j"\; filenames="A20061010448100151.png,A20061010448100181.png"\; state="\{\{state\}\}">j</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}\frac{\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 90</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; c</span>}}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="j"\; filenames="A20061010448100151.png,A20061010448100181.png"\; state="\{\{state\}\}">j</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}\frac{\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 130</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; c</span>}}}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; ,</span>$

In the formula, c is the propagation speed of light in vacuum, θ is the horizontal azimuth, and r is the radius of the circumscribed circle of the regular nonagon. The value of r should ensure that the half power angle of a single beam is not less than 40°.

The distance x from the RF switch of the feeder to the power divider/combiner satisfies 1/4 of the wavelength in the medium, and the distance y+z from the RF switch of the feeder to the microstrip antenna unit satisfies odd multiples of the wavelength in the 1/4 medium.

The drive circuit generates a corresponding drive signal according to the decoding signal. The process is that when the logic level input is 0V, the drive circuit outputs a bias voltage of 3.3V, and when the logic level input is 3.3V, the output bias voltage is 3.3V. The voltage is -3.3V; the process of the radio frequency switch gating and turning off the corresponding transmission feeder and the antenna unit connected to it is that when the bias voltage of the radio frequency switch is 3.3V, the switch diode is turned on, and the microstrip transmission feeder A short circuit at the switching diode makes the two open circuits of the power distribution/combiner and the antenna unit, so that the antenna unit does not work; when the bias voltage is -3.3V, the switching diode is cut off, and the microstrip transmission feeder is open at the switching diode. The two places of the power distribution/combiner and the antenna unit are short-circuited, and the corresponding antenna unit works.

The radio frequency switching circuit adopts an external compensation method, including a series resonant circuit composed of a compensation inductance and a DC blocking capacitor, which offsets the parasitic capacitance formed by the switching diode at high frequency, and compensates for insertion loss; The parasitic inductance formed by the diode at high frequencies is used to compensate for the isolation.

Compared with the beam switching method of the existing three-plane array antenna system, the beneficial effects of the present invention are:

(1) The symmetry of the array structure ensures the symmetry and consistency of the beam. The present invention feeds power directly from the power splitter at the center of the regular polygonal end face, and each RF signal reaches the antenna unit through a feeder line of exactly the same length, and the adjacent antenna units form an array to form a beam, so that there will be no non-in-phase lateral The excitation beams are all in-phase excitation beams, which significantly improves the main lobe and side lobe suppression ratio of the beams, improves the ability of the system to suppress interference, and ensures the consistency of each beam. In the specific implementation process, once the number of antenna elements working at the same time is determined, it cannot be changed.

(2) In the beam switching system, in order to generate multiple beam directions pointing to different directions, it is often necessary to gate or cut off the feeders of different antenna groups. To control any feeder line, switch circuits must be set at both ends of the transmission line to effectively cut off the radio frequency signal. As a result, the beam switching antenna system requires a large number of PIN diode circuits, which increases the complexity of the system, increases the overall insertion loss, and increases the difficulty of wiring. For example, the three-sided array antenna in the background technology adopts a "sector-beam" two-stage structure, which makes the switching system more complicated, requiring a total of 39 PIN diodes and corresponding capacitors and inductors, and due to the non-ideality of the switch, there are Insertion loss and limited isolation will increase the standing wave ratio of the antenna array and reduce the efficiency. The method of the present invention completely simplifies the whole switch system, each antenna unit only needs one switch to control its on-off, and the whole system only needs N (N is the number of faces of positive polygonal prism) PIN diodes in total, which not only greatly reduces the Cost, while reducing the impact of switch non-idealities on the beam, improving the consistency of the beam.

(3) All the beams of the antenna array of the present invention are generated by in-phase excitation by multiplexing adjacent units, no phase shifter (that is, delay lines with different lengths) is required, and the beam consistency is good; a huge radio frequency switch array is no longer required to Choosing the delay line simplifies the circuit design, reduces the number of components, reduces the insertion loss, and further reduces the cost.

(4) The switching diode (PIN Diode) circuit mainly includes a series single-pole single-position structure, a shunt type single-pole single-position structure, and a composite structure. Although these switching circuit structures have their own advantages and disadvantages in the simulation, it is difficult to work ideally in a high-frequency environment, mainly due to poor isolation and insertion loss performance. This is because the diode works at radio frequency, and its internal parasitic inductance and parasitic capacitance cannot be ignored. The invention effectively compensates the internal parasitic reactance of the diode under the high-frequency environment by constructing an external resonant circuit, so that the switching circuit has better isolation and insertion loss performance.

Description of drawings

FIG. 1 is a structural schematic diagram of a regular nine-prism beam-switching smart antenna of the present invention. Among them, Figure 1(a) is the external structure; Figure 1(b) is the internal structure.

FIG. 2 is a schematic circuit diagram of the radio frequency switch 3 in FIG. 1 .

FIG. 3 is a schematic diagram of the driving circuit of the driving circuit board 5 in FIG. 1( b ).

FIG. 4 is a logic control block diagram of the logic control circuit board 6 in FIG. 1( b ).

FIG. 5 is a schematic diagram of beamforming and switching states of the device in FIG. 1 . Figure 5a shows the forward beam formed by coherent superposition of three adjacent microstrip antenna units; Figure 5b shows the next forward beam switched to the left in sequence; Figure 5c shows the forward beam switched in any direction; Figure 5d is An isotropic beam formed by three spaced microstrip antenna elements when user tracking is not required.

FIG. 6 is a beam pattern diagram of the beam switching smart antenna in FIG. 1 . Among them, Figure 6(a) is the simulation result graph; Figure 6(b) is the actual measurement result graph.

Fig. 7 is the test result of the working frequency band of the beam switching smart antenna in Fig. 1, where Fig. 7(a) is the test result from 2.400GHz to 2.483GHz, and Fig. 7(b) is the test result from 2.0GHz to 3.0GHz.

Fig. 8 is the simulation result of the radiation pattern when three adjacent antenna elements on the regular nine-prism surface in Fig. 1 form an array.

FIG. 9 is a simulation result of insertion loss and isolation of the radio frequency switch 3 in FIG. 2 .

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific examples.

As shown in Figure 1, a specific embodiment of the regular polyhedron beam switching smart antenna device of the present invention is a positive nine prism beam switching smart antenna device, including a power distribution/combiner 2, radio frequency switch 3, microstrip antenna unit 10 and feeder 4. Drive circuit and logic control circuit; the shape of the antenna device is a regular nine prism, the microstrip antenna unit 10 is arranged on each cylindrical surface 1 of the regular nine prism, and the power distribution/combiner 2 is arranged on a vertical In the center of the regular nonagonal end face 8 of the regular nonagonal prism face 10, the radio frequency switches 3 are evenly distributed on the periphery of the regular nonagonal end face 8, and are connected to the power distribution/combiner 2 and the microstrip antenna unit 10 by feeders 4, respectively , the number of the radio frequency switch 3 and the microstrip antenna unit 10 is nine; the drive circuit and the logic control circuit are respectively arranged on the drive circuit board 5 and the logic control circuit board 6 having the same shape as the regular nonagonal end face 8, And sequentially assembled on the upper part of the inner cavity of the regular nine prism. The shape of the regular polyhedron antenna device of the present invention is not limited to a regular nine prism, but may also be a regular polygonal pyramid or a regular polygonal trapezoidal platform.

The regular nine prism surface 1 can adopt two kinds of dielectric materials as shown in Table 1, and the center-to-center spacing of each antenna unit 10 is not more than half of the wavelength of the highest frequency radio wave in the working frequency band. Each beam is generated by in-phase excitation of three adjacent antenna elements 10 , and its pattern is shown in FIG. 7 . The input/output port of the power distribution/combiner 2 adopts a 50 ohm SMA connector to perform power distribution/combination on three adjacent antenna units 10, and the inner side of the antenna device relative to the regular nine-prism surface 1 is a metal reflective surface 7 .

As shown in Figure 2, the circuit of the RF switch 3 adopts an improved Shunt SPST structure (shunt-type single-pole single-throw switch), including a diode PIN DIODE, whose anode is in common with the compensation inductor L1, input and output coupling capacitors C1, and C2. Connected, the bias input terminal BIAS of the compensation inductor L1 is connected with a DC blocking capacitor C3; the negative pole of the diode PIN DIODE is connected with an inductor L2 and a compensation capacitor C4, and the RF input RF IN and output RF OUT are respectively connected to the power distribution/combination through the feeder 4 The device 2 is connected to the microstrip antenna unit 10. The insertion loss and isolation characteristics of this circuit are shown in Figure 8. Inductor L1 is used to compensate insertion loss, capacitor C4 is used to compensate isolation, and inductor L2 is used to provide a DC path.

As shown in FIG. 3 , the driving circuit on the driving circuit board 5 includes a triode T1 and a triode T2 . The base of the transistor T1 is connected to the logic control circuit output LOGIC through the current limiting resistor R1, the collector of the transistor T1 is connected to the base of the transistor T2 through the coupling resistor R3, and the base of the transistor T2 is connected in parallel with the emitter. A diode D1, the cathode of the diode D1 is connected to the bias input BIAS of the RF switch 3 through the inductor L1, and the transistors T1 and T2 can be PNP transistors. The function of the drive circuit is to provide the appropriate bias voltage and current for the diode PIN DIODE of the RF switch 3 according to the logic signal given by the logic control circuit. The logic levels are 0V and 3.3V, and the bias voltage is ±3.3V. Close and strobe the corresponding RF switch 3 .

As shown in Figure 4, the logic control circuit adopts CPLD (complex programmable logic controller) design, and this CPLD adopts the control logic module of ALTERA EPM3032A model, and its input is connected with the host computer through the host computer interface on the logic control circuit board 6, And decode the instructions from the host computer. The output of the CPLD is connected to the drive circuit on the drive circuit board 5 through the drive circuit interface, and generates corresponding logic signals to control the drive circuit, and then the drive circuit generates corresponding drive signals to drive the RF switch 3 to perform beam switching.

FIG. 5 is a schematic diagram of top-view beamforming and switching states of the device in FIG. 1 . The three thick black lines indicate the gated microstrip antenna unit 10', and the three adjacent microstrip antenna units 10' work at the same time, coherently superimposed to form a goose-egg-shaped forward beam I (Fig. 5a). The switched beam can be the next beam II in sequence (Fig. 5b) or beam III in any direction (Fig. 5c). Which beam to switch depends on the location of the receiver. The process of beam switching is to ensure that the beam is aligned with the receiver as much as possible. When there is no need for user tracking or beam switching, three microstrip antenna units 10' spaced apart from each other can work simultaneously to form three structurally symmetrical beams IV, which can be used as an isotropic antenna after being superimposed (Fig. 5d).

The beam forming and switching method of the present invention based on the above-mentioned regular nine-prism smart antenna device are as follows:

Control process: According to the position information of the receiver, the host computer sends instructions, through the logic control circuit and the drive circuit, the radio frequency switch 3 gates the three adjacent antennas corresponding to the direction of the receiver among the nine microstrip antenna units 10 unit 10', and the remaining six microstrip antenna units 10 are turned off. The three gated microstrip antenna elements 10' form a circular array, thereby forming a beam I directed towards the receiver. Since the receiver has certain mobility, when its location changes, the corresponding channel state information will also change accordingly. The host computer reselects the microstrip antenna unit 10' that needs to be selected according to the current channel state information, and sends a switching instruction. The specific process is that the host computer is connected to the logic control circuit of the logic control board 6 through the host computer interface located on the logic control board 6, and the host computer can periodically detect the signal strength of each different direction and thus issue instructions to perform beam switching; After the logic control circuit receives the switching command, the control logic CPLD decodes the command, and sends the decoded signal to the drive circuit board 5 through the drive circuit interface, and the drive circuit on the drive circuit board 5 generates a switch according to the decoded signal. The corresponding drive signal is sent to the radio frequency switch 3, and the radio frequency switch 3 gates another group of adjacent three microstrip antenna units 10' through the feeder 4, and turns off the rest of the microstrip antenna units 10, thereby realizing Smart switch from beam I to beam II or III. In the process of switching from beam I to beam II, the adjacent microstrip antenna unit 10' can be reused. Since the switched beams are all generated by in-phase excitation, no phase shifter or delay line is needed.

The process of the radio frequency switch 3 gating and shutting off the corresponding transmission feeder 4 and the antenna unit 10 connected to it is, when the bias voltage of the radio frequency switch (3) is 3.3V, the diode PIN DIODE conducts, and the microstrip transmission feeder 4 A short circuit at the diode PIN DIODE makes the power distribution/combiner 2 and the microstrip antenna unit 10 two open circuits, so that the microstrip antenna unit 10 does not work; when the bias voltage is-3.3V, the diode PIN DIODE cuts off, and the microstrip antenna unit The belt transmission feeder 4 is open at the diode PIN DIODE, so that the power distribution/combiner 2 and the microstrip antenna unit 10 are short-circuited, and the corresponding microstrip antenna unit 10 works.

Signal flow: The radio frequency signal is fed from the input port of the power distribution/combiner 2, passes through three feeders 4, and is emitted by the three adjacent microstrip antenna units 10' that are gated. In order to ensure impedance matching, the characteristic impedance of the input port is 50 ohms, and the characteristic impedance of the three feeders is 150 ohms. The symmetrical structure ensures that the length of each feeder 4 is exactly the same, and the radio frequency signal can reach each gated microstrip antenna unit 10' at the same time, and through coherent superposition, an in-phase beam is formed in the normal direction of the circumscribed circle of the regular nine prism.

Array design: In order to enable the nine beams generated by the regular nine prism to cover the horizontal azimuth θ in the range of 360°, the horizontal half-power angle  of a single beam cannot be less than 40°. The size of  can be changed by changing the radius r of the circumscribed circle of the regular nine prism or the number of adjacent microstrip antenna elements 10'. In general, the smaller the radius r, the larger the value of the half-power angle , but the mutual coupling between the microstrip antenna elements 10' will also increase; the fewer the number of microstrip antenna elements 10', the larger the value of the half-power angle  The larger the value, the lower the array gain. Therefore, when designing the array, it is necessary to comprehensively consider multiple factors such as the size of the regular nine prism, the number of adjacent microstrip antenna units 10' working at the same time, and the array gain.

The adjacent three microstrip antenna elements 10' that are gated form a ring array, and its array factor can be expressed as:

where c is the propagation speed of light in a vacuum, and θ is the horizontal azimuth angle, which leads to the theoretical direction diagram in Fig. 6(a). For the regular nine prism in this example, the radius r of the circumscribed circle is determined to be 70.1mm, and the number of microstrip antenna units 10' to be selected at the same time is three.

Feeder size: each feeder 4 only needs one radio frequency switch 3 to control. The feeder distance x from the radio frequency switch 3 to the power divider/combiner 2 satisfies 1/4 of the wavelength in the medium. The feeder distance y+z from the RF switch 3 to the microstrip antenna unit 10 satisfies an odd multiple of 1/4 of the wavelength in the medium, which is 3 times in this example, and can also be 5 or 7 times. Such a setting enables the radio frequency switch 3 to switch off both ends of the feeder 4 at the same time.

The value of the wavelength λ _g in the medium is related to the working frequency f, the dielectric constant ε _r of the medium, the thickness d of the medium plate, and the characteristic impedance of the radiation unit. Table 1 shows the selection of the wavelength _λg in the medium of the two plates (operating frequency f=2.441GHz).

Table 1 Sheet name _εr d 150 ohms 86.6 ohms 50 ohms 1/4λ _g (mm) 1/4λ _g (mm) 1/4λ _g (mm) Arloncuclod 2.17 1.5mm 23.576 22.954 22.325 F4B-2 2.65 3mm 21.796 21.048 20.314

This distance selection method greatly simplifies the design of the PIN Diode, reduces the number of switches required by the entire system, reduces insertion loss and power consumption, improves system performance, and reduces costs.

Compensation circuit of RF switch 3: Due to the parasitic reactance inside the RF switch 3 and the distribution parameter characteristics of the microstrip medium itself in the RF environment, the isolation of the RF switch 3 will be insufficient, and the insertion loss will be large, which will affect the system performance. The present invention uses a special circuit to compensate it. Through simulation, it is found that the parasitic capacitance in the radio frequency switch 3 has a great influence on the insertion loss of the switch; while the isolation degree is relatively sensitive to the parasitic inductance. The compensation method is to construct an external resonant circuit, see Figure 2 for details. Inductor L1 and capacitor C3 form a series resonant circuit to offset the parasitic capacitance formed by the switching diode at high frequency and compensate for insertion loss; capacitor C4 and inductance L2 form a parallel resonant circuit to offset the parasitic inductance formed by the switching diode at high frequency for compensation isolation Spend. Under the operating frequency of 2.441GHz, the values of L1, L2, C3, and C4 can be selected as 6.8nH, 33nH, 1.2pF, and 10pF, respectively.

Fig. 6 is a comparison between the simulation results and the actual measurement results of the beam switching pattern based on the regular polygonal prism smart antenna. Taking the regular nine prism as an example, it can be seen from the figure that the simulation results are quite close to the measured results, and the measured beams have good consistency.

Fig. 7 is the test result of the working frequency band of the application example of the present invention. The application environment is a wireless local area network based on IEEE802.11b/g, and its working frequency band is the ISM (Industrial Science Medical) frequency band, but the present invention is not limited to this frequency band, but is applicable to any microwave band. From the test results (a) in Figure 7, it can be seen that the standing wave ratio at the center frequency is lower than 1.3, and the standing wave ratio in the 2.400GHz-2.475GHz frequency band does not exceed 2, indicating that the radiation efficiency of the antenna is relatively high. From the test result (b) in Figure 6, it can be seen that there is only one resonance point in the 2.0GHz to 3.0GHz frequency band, so the antenna has no out-of-band radiation, has high efficiency, and will not cause interference to other frequency bands.

Fig. 8 shows the performance of the triad array when the side length d of the regular nonagonal end face 8 is 50 mm. It can be seen from Figure 7 that the 3dB main lobe width can reach 40 degrees, and the main lobe side lobe suppression ratio exceeds 14dB. It can meet the requirements for space coverage and effectively suppress interference.

Figure 9 shows the Microwave Office simulation results of the insertion loss and isolation of the RF switch 3. From the curve in Figure 9, it can be seen that the insertion loss at the center frequency is 0.128dB, and the isolation is 29.2dB. Obviously, the circuit in the present invention effectively compensates the parasitic capacitance and inductance of the PIN DIODE, and well eliminates its influence on the switching circuit.

The method of the present invention is applicable to a multi-antenna system with a regular polyhedron structure, including a regular polygonal prism, a regular polygonal pyramid, or a regular polygonal trapezoidal platform and the like. It is suitable for beam switching systems such as adaptive antenna arrays, smart antennas, and phased array radars implemented by radio frequency.

Claims (8)

1. the wave beam based on regular polyhedron intelligent antenna assembly forms and changing method, it is characterized in that, comprises following control procedure:

A) with the input port feed-in of radiofrequency signal from power division/synthesizer (2), positional information according to receiver, host computer sends the gating instruction, by logic control circuit and drive circuit, by three feeder lines (4) that connect three antenna elements (10 ') corresponding receiver direction, adjacent in radio-frequency (RF) switch (3) nine microband antenna units of gating (10), emission of radio frequency signals is gone out by adjacent three microband antenna units (10 ') of gating; Simultaneously, radio-frequency (RF) switch (3) is turn-offed the feeder line (4) that is connected with all the other six microband antenna units (10); Adjacent three microband antenna units (10 ') by gating are formed an annular array, and form the wave beam (I) of a beacon receiver;

B) when receiver location changes, host computer is reselected adjacent three microband antenna units (10 ') that need gating according to the detected current channel condition information of periodicity, sends switching command to logic control circuit plate (6);

C) after logic control circuit plate (6) is received switching command, CPLD module by logic control circuit is deciphered this instruction, and decoded signal is sent to the drive circuit of drive circuit board (5), drive circuit produces the corresponding driving signal according to decoded signal, and drive signal is sent to radio-frequency (RF) switch (3), radio-frequency (RF) switch (3) is by another adjacent three microband antenna units (10 ') of group of feeder line (4) gating and turn-off all the other antenna elements (10), thereby wave beam (I) is switched to wave beam (II) or (III).

2. the wave beam based on regular polyhedron intelligent antenna assembly according to claim 1 forms and changing method, it is characterized in that, the radiofrequency signal of described input port feed-in from power division/synthesizer (2) arrives three adjacent microband antenna units (10 ') of gating simultaneously, through coherent superposition, form the homophase wave beam in regular polygon circumscribed circle normal orientation.

3. the wave beam based on regular polyhedron intelligent antenna assembly according to claim 1 forms and changing method, it is characterized in that, described adjacent three microband antenna units (10 ') by gating are formed an annular array, and its array factor formula is:

C is a light propagation velocity in a vacuum in the formula, and θ is the azimuth, and r is the circumradius of positive nonagon, and the value of r will guarantee that the half-power angle of single wave beam is not less than 40 °.

4. the wave beam based on regular polyhedron intelligent antenna assembly according to claim 1 forms and changing method, it is characterized in that, radio-frequency (RF) switch (3) on the described feeder line (4) is 1/4 medium medium wavelength to power division/synthesizer (2) apart from x, the radio-frequency (RF) switch (3) on the feeder line (4) to the distance y+z of microband antenna unit (10) be the odd-multiple of 1/4 medium medium wavelength.

5. the wave beam based on regular polyhedron intelligent antenna assembly according to claim 1 forms and changing method, it is characterized in that, described drive circuit produces the corresponding driving signal according to decoded signal, its process is, when logic level is input as 0V, drive circuit output offset voltage is 3.3V, and when logic level was input as 3.3V, output offset voltage was-3.3V;

6. form and changing method based on the wave beam of regular polyhedron intelligent antenna assembly according to claim 1 or 5, it is characterized in that, described radio-frequency (RF) switch (3) gating and turn-off corresponding transmission feeder (4) and the process of coupled antenna element (10) is, when the bias voltage of radio-frequency (RF) switch (3) is 3.3V, switching diode PIN DIODE conducting, little band transmission feeder (4) is in the short circuit of switching diode place, make power division/synthesizer (2) and antenna element (10) two places open a way, thereby this antenna element (10) is not worked; When bias voltage be-during 3.3V, switching diode PIN DIODE ends, little band transmission feeder (4) is at switching diode place open circuit, makes power division/synthesizer (2) and antenna element (10) two place's short circuits, corresponding antenna element (10) work.

7. the wave beam based on regular polyhedron intelligent antenna assembly according to claim 1 forms and changing method, it is characterized in that, described radio-frequency (RF) switch (3) adopts the method for external circuit compensation, constitute series resonant tank with inductance (L1) and electric capacity (C3), offset the parasitic capacitance that switching diode forms at high frequency, loss is inserted in compensation; Constitute the shunt-resonant circuit with electric capacity (C4) and inductance (L2), offset switching diode, be used to compensate isolation in the stray inductance that high frequency forms.

8. the wave beam based on regular polyhedron intelligent antenna assembly according to claim 1 forms and changing method, it is characterized in that switch in the process of wave beam II at wave beam I, adjacent microband antenna unit (10 ') can be re-used.

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