Low-cost, high-performance 5-bit programmable phased array antenna operating in Ku band

Abstract

The present invention discloses a low-cost, high-performance 5-bit programmable phased array antenna operating in the Ku band. The programmable phased array antenna consists of three parts, including a reconfigurable radiating unit with 1-bit (180 degrees) phase quantization, a digital phase shifter with 4-bit (168.75 degrees) phase quantization, and a feeding network. The radio frequency signal enters the antenna from the phased array antenna port, and the states of the PIN diode and the varactor diode loaded in the programmable phased array antenna are adjusted by an external voltage divider control circuit to generate corresponding codes, thereby achieving 0°-60° high-precision beam scanning. Compared with the traditional phased array, the programmable phased array antenna does not require a large number of electronic phase shifters or T / R components, so it has a simple structure, low cost, planarization, easy integration with other devices, and low loss, and has high application value in the microwave field.

Description

Technical Field

[0001] The present invention relates to a low-cost, high-performance 5-bit programmable phased array antenna operating in the Ku band, which can be used in the fields of communications, radars, integrated circuits, etc. Background Art

[0002] Phased array antennas are widely used in various wireless communication environments such as radar systems, target tracking, and satellite communication systems due to their fast and high-precision beam scanning capabilities. However, a large number of electronic phase shifters or T / R elements are introduced into traditional phased arrays, which undoubtedly brings problems such as high cost, high power consumption, and too large a size to be integrated with other components.

[0003] Reconfigurable array antennas have the advantages of miniaturization, light weight, low cost, and easy integration. Among them, pattern reconfigurable antennas play an important role in dynamically changing scenarios and have been proven to have powerful real-time beam adjustment capabilities. Therefore, pattern reconfigurable array antennas are considered to be an alternative to traditional phased arrays and have received increasing attention. They have been widely studied in microwave circuits and antenna design. Summary of the invention

[0004] Technical Problem: The purpose of this invention is to realize a low-cost, high-performance 5-bit programmable phased array antenna operating in the Ku band. The phased array antenna should have high-performance beam scanning capability, low cost, low profile, low loss, planarization, miniaturization, and easy integration.

[0005] Technical solution: A low-cost, high-performance 5-bit programmable phased array antenna operating in the Ku band of the present invention consists of three parts, including a reconfigurable radiating unit, a digital phase shifter with 4-bit 168.75 degree phase quantization, and a feeding network; they are respectively located at the upper, middle, and lower parts of the antenna to form a layered structure; the phased array antenna includes a total of two dielectric substrates and three metal layer structures, namely, from top to bottom, an upper metal layer, an upper dielectric substrate, an intermediate metal layer, an adhesive layer, a lower dielectric substrate, and a lower metal layer; the upper metal layer is the radiation structure of the 5-bit programmable phased array antenna, the intermediate metal layer is a metal ground to prevent electromagnetic waves from leaking to the back of the antenna, and the lower metal layer is the feeding structure of the 5-bit programmable phased array antenna; the two dielectric substrates and the three metal layers are connected by an adhesive layer.

[0006] The thickness of the upper dielectric substrate is 1.524 mm, and the dielectric constant is ε r =3.55, loss tangent σ=0.0027 Rogers 4003C.

[0007] The lower dielectric substrate is Rogers 4003C with a thickness of 0.203 mm; the dielectric constant of the adhesive layer is εr =3.7, loss tangent σ=0.0027, Rogers 4450F, thickness is 0.1mm.

[0008] The reconfigurable radiating unit is 24×2 reconfigurable radiating units with 1-bit 180-degree phase quantization.

[0009] The reconfigurable radiation unit includes three parts: a radiation patch, an optional feeding structure and a bias circuit. The symmetry of the antenna structure is used to form a stable phase difference of 180 degrees. Two rectangular slots are distributed on the radiation patch in the direction of the electric field. The slotted radiation patch has a wider impedance bandwidth and lower cross polarization. The optional feeding structure is in the shape of a "Y" structure, and two first PIN diodes and a second PIN diode of model MADP-14020-907 are symmetrically placed at the end of the structure. By adjusting the switching state of the two PIN diodes, the current path of the electromagnetic wave on the optional feeding structure is selected. The bias circuit is used to isolate AC signals and DC signals respectively. The bias circuit for isolating AC signals is composed of a first bias line, a second bias line, a first grounding capacitor, and a second grounding capacitor. The circuit for isolating DC signals is composed of a third capacitor connected in series at the signal input end.

[0010] The 4-bit 168.75-degree phase quantized digital phase shifter comprises a 3-dB impedance conversion branch line coupler (b1), two reflective loads and a DC bias line; the branch line coupler uses a bent microstrip line to reduce its area; the two reflective loads are connected to the terminal of the branch line coupler, and are composed of two varactor diodes, namely a first varactor diode, a first varactor diode and transmission lines at both ends; the varactor diode requires an external DC bias voltage to change the capacitance value to generate a phase shift; the DC bias line is composed of a grounded capacitor connected to a quarter-wavelength high-impedance line, and has the function of isolating AC signals; two DC blocking capacitors, namely a first DC blocking capacitor and a second DC blocking capacitor, are connected in series at the input and output ends of the 4-bit 168.75-degree phase quantized digital phase shifter, and play the role of isolating DC signals.

[0011] The feeding network is a 1:24 feeding structure based on a coplanar waveguide structure, and its power division ratio adopts Taylor distribution.

[0012] The PIN diode and the varactor diode change the state of the PIN diode and the varactor diode through an external voltage divider circuit to generate corresponding codes and realize 0°-60° beam scanning; wherein, at the central frequency of radiation 14.8GHz, the scanning error of the phased array antenna is less than 1 degree at all scanning angles, the gain roll-off is less than 2.4dB, the sidelobe level is lower than -1dB, and the cross-polarization ratio is lower than -26dB.

[0013] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0014] 1. Programmable beam scanning: The present invention proposes a low-cost, high-performance 5-bit programmable phased array antenna operating in the Ku band, characterized in that the state of the PIN diode and the varactor diode is changed by an external voltage divider circuit to generate corresponding codes, thereby achieving 0°-60° beam scanning. Compared with traditional phased arrays, there is no need to use a large number of electronic phase shifters or T / R components.

[0015] 2. Simple structure, low cost, planarization, and easy integration with other devices: Compared with traditional phased arrays, the present invention does not require the use of a large number of electronic phase shifters or T / R components. It has low cost, simple structure, and high integration. It is easy to integrate with other high-frequency / planar circuits while meeting the requirements of miniaturization and planarization.

[0016] 3. High beam scanning accuracy, low sidelobe level, and low cross-polarization ratio: The present invention proposes a low-cost, high-performance 5-bit programmable phased array antenna operating in the Ku band, wherein at the center frequency of radiation (14.8GHz), the scanning error of the phased array antenna is less than 1 degree at all scanning angles, the gain roll-off is less than 2.4dB, the sidelobe level is lower than -1dB, the cross-polarization ratio is lower than -26dB, and the beam scanning performance is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 1 is a structural diagram of a reconfigurable radiation unit with 1-bit (180 degrees) phase quantization, wherein (a) the radiation unit structure decomposition diagram; (b) the radiation unit upper structure diagram; (c) the radiation unit lower structure diagram;

[0018] Figure 2 This is a simulation result diagram of the reflection coefficient of a reconfigurable radiating unit with 1-bit (180 degrees) phase quantization;

[0019] Figure 3 It is a graph of the electric field far-field phase and phase difference when the reconfigurable radiating unit with 1-bit (180 degrees) phase quantization works in the '0' and '1' states;

[0020] Figure 4 It is a reconfigurable radiation unit with 1-bit (180 degrees) phase quantization working at the center frequency (14.8GHz) E-plane, H-plane main polarization and cross-polarization radiation patterns; among them, (a) is the E-plane main polarization radiation pattern, (b) is the E-plane cross-polarization radiation pattern, (c) is the H-plane main polarization radiation pattern, and (d) is the H-plane cross-polarization radiation pattern;

[0021] Figure 5It is a block diagram of a digital phase shifter with 4-bit (168.75 degrees) phase quantization;

[0022] Figure 6 It is the transmission amplitude and transmission phase curve of the digital phase shifter with 4-bit (168.75 degrees) phase quantization working at different capacitance values ​​within the working frequency band;

[0023] Figure 7 is a structural decomposition diagram of the 5-bit programmable phased array antenna in Example 1;

[0024] Figure 8 The amplitude and phase curves of the 1:24 feeding network based on the coplanar waveguide and ground (CPWG) structure within the working frequency band; (a) is the amplitude curve; (b) is the phase curve;

[0025] Fig. 9 It is the phase coding diagram corresponding to each array element of the 5-bit programmable phased array antenna beam at different scanning angles in Example 1;

[0026] Fig.10 It is a reflection coefficient result diagram of the 5-bit programmable phased array antenna in Example 1 under 0°-60° beam scanning;

[0027] Fig.11 The beam pattern of the 5-bit programmable phased array antenna in Example 1 scanning at different frequencies of 0°-60°, wherein (a) is a low frequency point (14.4 GHz); (b) is a center frequency point (14.8 GHz); and (c) is a high frequency point (15.4 GHz).

[0028] Fig.12 The scanning performance result diagram of the 5-bit programmable phased array antenna in Example 1 at different frequencies and different scanning angles, wherein (a) is a gain curve diagram; (b) is a sidelobe level curve diagram; and (c) is a cross-polarization ratio curve diagram.

[0029] The figure includes: upper metal layer 1, upper dielectric substrate 2, middle metal layer 3, adhesive layer 4, lower dielectric substrate 5, lower metal layer 6, radiation patch 7, optional feeding structure 8, bias circuit 9, two rectangular slots 10, 3-dB impedance conversion branch line coupler 11, two reflective loads 12, and second bias circuit 13. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] Example 1

[0032] See also Figure 1-Figure 11 In this embodiment, a low-cost, high-performance 5-bit programmable phased array antenna operating in the Ku band is provided. The array antenna comprises: a reconfigurable radiating element with 1-bit (180 degrees) phase quantization, a digital phase shifter with 4-bit (168.75 degrees) phase quantization, and a feeding network.

[0033] The low-cost, high-performance 5-bit programmable phased array antenna operating in the Ku band includes two layers of dielectric substrates and three layers of metal structures; the upper metal layer is the radiation structure of the 5-bit programmable phased array antenna, the lower metal layer is the feeding structure of the 5-bit programmable phased array antenna, and the middle metal layer is the metal ground to prevent electromagnetic waves from leaking to the back of the antenna; the two layers of dielectric substrates are connected by an adhesive layer and realized by multi-layer PCB lamination technology. The dielectric substrate is selected with a dielectric constant of ε r =3.55, loss tangent σ = 0.0027 Rogers 4003C, where the thickness of the upper dielectric substrate is 1.524mm, the thickness of the lower dielectric substrate is 0.203mm; the adhesive layer uses a dielectric constant of ε r =3.7, loss tangent σ=0.0027 Rogers 4450F, thickness is 0.1mm; the metal material is copper, the thickness is 0.018mm.

[0034] Specifically, in this embodiment, the radiation unit is composed of 24×2 reconfigurable radiation units with 1-bit (180 degrees) phase quantization. The reconfigurable radiation unit uses the symmetry of the antenna structure to form a 180-degree stable phase difference, and is mainly composed of three parts: a radiation patch, an optional feeding structure, and a bias circuit. The radiation patch is different from the traditional rectangular patch. It has two rectangular slots distributed in the electric field direction. Compared with the traditional rectangular patch as a radiation patch, the slotted radiation patch has a wider impedance bandwidth and lower cross-polarization. The optional feeding structure is in the shape of a 'Y' structure, and two PIN diodes of model MADP-14020-907 are symmetrically placed at the end. By adjusting the switching state of the two diodes, the current path of the electromagnetic wave on the optional feeding structure can be selected. The bias circuit is used to isolate AC signals and DC signals respectively. The bias circuit for isolating AC signals is composed of a bias line and a 0.5pF grounding capacitor, and the DC signal is isolated by a 0.5pF capacitor connected in series at the signal input end.

[0035] Specifically, in this embodiment, a digital phase shifter with 4-bit (168.75 degrees) phase quantization is composed of a 3-dB impedance conversion branch line coupler, two reflective loads and a bias circuit. The branch line coupler uses a curved microstrip line to replace a quarter-wavelength transmission line, reducing its area by 33%; the two reflective loads are connected to the terminals of the branch line coupler, and are composed of two varactors (MAVR-011020-1411) and transmission lines at both ends. The varactor diode requires an external DC bias voltage to change the capacitance value to produce a phase shift. The DC bias line is composed of a 100pF grounding capacitor and a quarter-wavelength high-impedance line, which has the function of isolating AC signals. Two 100pF capacitors are connected in series at the input and output ends of the phase shifter to isolate DC signals.

[0036] Specifically, in this embodiment, a 1:24 feeding network based on a coplanar waveguide and ground (CPWG) structure is designed to feed the radiation element, and its power division ratio adopts Taylor distribution.

[0037] Specifically, in the embodiment, a low-cost, high-performance 5-bit programmable phased array antenna operating in the Ku band adjusts the states of the loaded PIN diode and varactor diode through an external voltage divider circuit to generate corresponding phase coding, thereby achieving 0°-60° arbitrary angle beam scanning. Among them, at the center frequency of radiation (14.8GHz), the scanning error of the phased array antenna is less than 1 degree at all scanning angles, the gain roll-off is less than 2.4dB, the sidelobe level is lower than -1dB, and the cross-polarization ratio is lower than -26dB.

[0038] In order to verify the correctness and advancement of the solution provided by this embodiment, simulation and testing were carried out, specifically including:

[0039] See also Figure 1 The structure diagram of the reconfigurable radiation unit with 1-bit (180 degrees) phase quantization, including (a) the radiation unit structure decomposition diagram; (b) the radiation unit upper structure diagram; (c) the radiation unit lower structure diagram. Its specific dimensions are shown in Table 1. In order to verify the unit performance, this embodiment is simulated in a commercial CST. See Figure 3 , which is the unit reflection coefficient simulation result diagram, we can see that the unit's operating bandwidth (S11|<-10dB) is 13.7GHz to 15.7GHz. Figure 3 , which is the electric field far-field phase and phase difference curve of the 1-bit reconfigurable radiation unit working in the '0' and '1' states. It can be seen that the unit can produce a stable 180-degree phase difference when working in the two states. Figure 4 , which is the E-plane, H-plane main polarization and cross-polarization radiation pattern of the 1-bit reconfigurable radiation unit working at the center frequency (14.8GHz).

[0040] See also Figure 5 The structure diagram of the digital phase shifter with 4-bit (168.75 degrees) phase quantization is shown in Table 2. Figure 6 , which is the structure diagram of the 4-bit digital phase shifter. The transmission amplitude and transmission phase curves under different capacitance values ​​in the working frequency band. It can be seen that when the capacitance changes from 0.048 to 0.144pF, within the required frequency band centered at 14.8GHz, the relative phase shift can be stabilized at 4-bit (168.75°), and the insertion loss in all states is less than -3dB.

[0041] See also Figure 7 This is the structural diagram of a low-cost, high-performance 5-bit programmable phased array antenna operating in the Ku band. It can be seen that the phased array antenna consists of 24×2 1-bit reconfigurable radiating elements, 24 4-bit digital phase shifters, and a 1:24 feed network based on a coplanar waveguide and ground (CPWG) structure.

[0042] See also Figure 8 The amplitude and phase curves of a 1:24 feeding network based on a coplanar waveguide and ground (CPWG) structure within the operating frequency band are shown. The feeding network adopts Taylor amplitude cutting. Figure 8 By comparing the design targets of the feeding network working at 14.4 GHz, 14.8 GHz and 15.4 GHz and the amplitude and phase curves of the actual simulation, it can be seen that the designed feeding network matches the target well.

[0043] See also Fig.10 The reflection coefficient result diagram of the 5-bit programmable phased array antenna in Example 1 under 0°-60° beam scanning, and the phase encoding diagram corresponding to each array element at different scanning angles can be found in Fig. 9 It can be seen that the -10dB impedance matching frequency band is 14.4 to 15.4GHz, and the reflection coefficients at different scanning angles are basically the same. The scanning beam patterns on the H plane at 14.4GHz, 14.8GHz, and 15.4GHz are shown in Figure 1. Fig.11 (a), (b) and (c). It can be seen that the 5-bit programmable phased array antenna can achieve high-precision scanning within the working frequency band.

[0044] See also Fig.11 The scanning performance result diagram of the 5-bit programmable phased array antenna in Example 1 at different frequencies and different scanning angles. Figure (a) is a gain curve diagram, and it can be seen that the maximum gain of the proposed phased array antenna at three frequency points in the 0° direction is 15.4dBi, 15.6dBi, 15.4dBi and their corresponding gain roll-offs are 2.9dB, 2.4dB, and 2.8dB, respectively. Figure (b) is a sidelobe level curve, and it can be seen that the sidelobe level of the radiation beam of the proposed phased array antenna at the center frequency of 14.8GHz is less than -16dB at all angles, and less than -15dB at both low and high frequencies. Figure (c) is a cross-polarization ratio curve diagram, and it can be seen that the ratio of the main polarization to the cross-polarization of the radiation beam of the proposed phased array antenna at the center frequency of 14.8GHz is less than -30dB at all angles, and less than -25dB at both low and high frequencies. The above results further demonstrate that the 5-bit programmable phased array antenna described in the present invention has the performance of high scanning accuracy, low sidelobe and low cross-polarization.

[0045] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A low-cost, high-performance 5-bit programmable phased array antenna operating in the Ku band, characterized in that: The phased array antenna is composed of three parts, including a reconfigurable radiation unit (a), a digital phase shifter with 4-bit 168.75 degree phase quantization (b) and a feeding network (c); they are respectively located at the upper, middle and lower parts of the antenna to form a layered structure; the phased array antenna comprises a total of two dielectric substrates and three metal layer structures, namely, from top to bottom, an upper metal layer (1), an upper dielectric substrate (2), an intermediate metal layer (3), an adhesive layer (4), a lower dielectric substrate (5), and a lower metal layer (6); the upper metal layer is a radiation structure of a 5-bit programmable phased array antenna, the intermediate metal layer is a metal ground to prevent electromagnetic waves from leaking to the back of the antenna, and the lower metal layer is a feeding structure of the 5-bit programmable phased array antenna; the two dielectric substrates and the three metal layers are connected by an adhesive layer; The reconfigurable radiation unit (a) comprises a radiation patch (a1), an optional feeding structure (a2) and a bias circuit (a3), and utilizes the symmetry of the antenna structure to form a 180-degree stable phase difference; two rectangular slots (a1.1) are distributed on the radiation patch (a1) in the electric field direction, and the slotted radiation patch has a wider impedance bandwidth and lower cross-polarization; the optional feeding structure (a2) is in the shape of a "Y" structure, and two MADP-14020-9 are symmetrically placed at the end thereof. 07, the first PIN diode (P1) and the second PIN diode (P2), by adjusting the switch state of the two PIN diodes, select the current path of the electromagnetic wave on the selectable feeding structure; the bias circuit (a3) ​​is used to isolate the AC signal and the DC signal respectively, the bias circuit for isolating the AC signal is composed of the first bias line (L1), the second bias line (L2) and the first grounding capacitor (C1), the second grounding capacitor (C2), and the circuit for isolating the DC signal is composed of the third capacitor (C3) connected in series to the signal input end; The 4-bit 168.75-degree phase quantized digital phase shifter (b) comprises a 3-dB impedance conversion branch line coupler (b1), two reflective loads (b2) and a DC bias line (b3); the branch line coupler (b1) uses a bent microstrip line to reduce its area; the two reflective loads (b2) are connected to the terminals of the branch line coupler (b1), and are composed of two varactor diodes, namely a first varactor diode (B1), a second varactor diode (B2) and transmission lines at both ends; the varactor diode requires an external DC bias voltage to change the capacitance value to generate a phase shift; The DC bias line (b3) is composed of a grounded capacitor (C4) connected to a quarter-wavelength high-impedance line, which has the function of isolating AC signals. Two DC blocking capacitors, namely the first DC blocking capacitor (C5) and the second DC blocking capacitor (C6), are connected in series at the input and output ends of the 4-bit 168.75-degree phase quantized digital phase shifter (b), which play the role of isolating DC signals. The feeding network (c) is a 1:24 feeding structure based on a coplanar waveguide structure, and its power division ratio adopts Taylor distribution; The PIN diode and the varactor diode change the state of the PIN diode and the varactor diode through an external voltage divider circuit to generate corresponding codes and realize 0°-60° beam scanning; wherein, at the central frequency of radiation 14.8GHz, the scanning error of the phased array antenna is less than 1 degree at all scanning angles, the gain roll-off is less than 2.4 dB, the sidelobe level is lower than -1dB, and the cross-polarization ratio is lower than -26 dB.

2. The low-cost, high-performance 5-bit programmable phased array antenna operating in the Ku band according to claim 1, characterized in that , the thickness of the upper dielectric substrate (2) is 1.524 mm, and the dielectric constant is ε r =3.55, Rogers 4003C with loss tangent σ=0.0027.

3. The low-cost, high-performance 5-bit programmable phased array antenna operating in the Ku band according to claim 1, characterized in that , the lower dielectric substrate (5) is Rogers 4003C, with a thickness of 0.203 mm; the dielectric constant of the adhesive layer is ε r =3.7, loss tangent σ=0.0027, Rogers 4450F, thickness is 0.1mm.

4. A low-cost, high-performance 5-bit programmable phased array antenna operating in the Ku band according to claim 1, characterized in that , the reconfigurable radiating unit (a) is 24×2 reconfigurable radiating units with 1-bit 180-degree phase quantization.

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