Miniaturized ultra-wideband Vivaldi antenna with reconfigurable dual-polarization angle and frequency

Abstract

The invention discloses a miniaturized ultra-wideband and dual-polarization angle and frequency reconfigurable Vivaldi antenna, which comprises two antenna units which are arranged in a crisscross manner, each of the two antenna units comprises a dielectric substrate, an antenna radiating surface, a feed port and a PIN diode, the antenna radiating surface is divided into a high-frequency radiating surface and a low-frequency radiating surface, and the feed port is connected with the dielectric substrate. The high-frequency radiating surface and the low-frequency radiating surface are connected through a PIN diode, and the working frequency is selected through the connection and disconnection of the PIN diode; the high-frequency radiation surface is provided with a feed port. And an auxiliary bracket capable of selecting a plurality of cross angles is arranged at the cross connection position of the two antenna units. Compared with an existing dual-polarization Vivaldi antenna, the dual-polarization Vivaldi antenna can be selectively provided with a bridge to achieve switching between single polarization and dual polarization, a multi-angle dual-polarization adjusting effect is achieved by changing the cross direction through the support, and space utilization and multi-scene application are achieved by fully utilizing the array interval size.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, and in particular to a miniaturized, ultra-wideband, dual-polarization angle and frequency reconfigurable Vivaldi antenna. Background Technology

[0002] Through-wall radar systems transmit low-frequency electromagnetic waves towards walls using radar equipment, and detect, locate, and image targets behind the wall based on the echo signals. To improve system resolution, modern radar systems use array antennas as the front end; the larger the array, the higher the accuracy. This necessitates smaller antenna sizes to maintain the overall mobility of the system. The antenna is a crucial component of through-wall detection systems, and its performance directly affects the system's detection range, resolution, and anti-jamming capabilities.

[0003] Vivaldi antennas, due to their ultra-wideband and low profile characteristics, are well-suited for research as array antennas. Based on the antenna's operating principle, the radiating patch can be divided into two parts: region I with a smaller opening and region II with a larger opening. When the antenna is operating, the majority of the high-frequency current is radiated from region I, with the remaining small portion propagating and radiating into region II. The opening width of region II is determined by the low-frequency cutoff frequency, which is much larger than the wavelength corresponding to the high-frequency frequencies. Therefore, the high-frequency current is significantly affected by surface waves in this region, thus impacting the antenna's end-fire capability.

[0004] Through-wall radar systems require the use of different microwave frequency bands, which existing Vivaldi antennas cannot meet. Furthermore, when the existing Vivaldi antennas are small in size, the gain at low frequencies is difficult to meet practical application requirements. Dual-polarized Vivaldi antennas that achieve dual-polarization radiation through a cross-shaped interlocking method suffer from a fixed cross-angle. Summary of the Invention

[0005] To overcome the aforementioned problems in the prior art, this invention proposes a miniaturized ultrawideband Vivaldi antenna with reconfigurable dual-polarization angle and frequency.

[0006] The technical solution adopted by this invention to solve its technical problem is: a miniaturized ultra-wideband Vivaldi antenna with reconfigurable angle and frequency dual polarization, comprising two antenna elements placed in a cross shape. Each antenna element includes a dielectric substrate, an antenna radiating surface, a feed port, and a PIN diode. The antenna radiating surface is divided into a high-frequency radiating surface and a low-frequency radiating surface, which are connected by a PIN diode. The operating frequency is selected by the conduction and disconnection of the PIN diode. A feed port is provided on the high-frequency radiating surface. The two antenna units are provided with an auxiliary bracket at the cross-connection position, which allows for multiple cross-angle selection.

[0007] The aforementioned miniaturized ultrawideband Vivaldi antenna with reconfigurable angle and frequency dual polarization features a slotted design within its high-frequency and low-frequency radiating surfaces.

[0008] The aforementioned miniaturized ultrawideband Vivaldi antenna with reconfigurable angle and frequency dual polarization comprises two antenna elements inserted into a polygonal passivated slot.

[0009] The aforementioned miniaturized ultrawideband Vivaldi antenna with reconfigurable angle and frequency dual polarization has two antenna elements placed in a cross shape, with the broken antenna radiating surface corrected by a metal connector.

[0010] The aforementioned miniaturized ultrawideband Vivaldi antenna with reconfigurable angle and frequency dual polarization includes an auxiliary support comprising a first fixing plate, a second fixing plate, and a snap-fit ​​plate. The first fixing plate and the second fixing plate are rotatably connected at one end, and the snap-fit ​​plate is rotatably disposed at the other end of the first fixing plate. The second fixing plate is provided with multiple slots, and the snap-fit ​​plate cooperates with the slots to adjust the angle between the first fixing plate and the second fixing plate. The first fixing plate and the second fixing plate are respectively used to fix two antenna elements.

[0011] The aforementioned miniaturized ultrawideband Vivaldi antenna with reconfigurable dual-polarization angle and frequency has an outer frame structure provided on the exterior of the two antenna elements.

[0012] The aforementioned miniaturized ultrawideband Vivaldi antenna with reconfigurable dual-polarization angle and frequency has an outer frame structure surrounding the antenna, and the shape of the outer frame structure is variable.

[0013] The aforementioned miniaturized ultrawideband Vivaldi antenna with reconfigurable dual polarization angle and frequency has an outer frame structure consisting of multiple blocks, which are installed in a toothed, segmented manner.

[0014] The aforementioned miniaturized ultrawideband Vivaldi antenna with reconfigurable dual-polarization angle and frequency has an outer frame structure made of copper sheet.

[0015] The beneficial effects of this invention are that, addressing the problem that the gain of Vivaldi antennas at low frequencies is difficult to meet practical application requirements when the antenna size is small, this invention combines two methods: cross-nesting and edge slotting. It also sets an outer frame structure with toothed cutting on the outside of the antenna. Dual-port feeding through a bridge can improve the antenna gain. Without changing the original antenna size, it can effectively optimize the low-frequency gain of traditional Vivaldi antennas. The outer frame structure made of thin copper sheet can improve the effective operating frequency range of the system without affecting the antenna quality, thus achieving the goal of antenna miniaturization.

[0016] To address the issue of fixed cross angles in existing dual-polarized Vivaldi antennas, the new dual-polarized Vivaldi antenna improves the contact surface of the physical cross structure, allowing for selective switching of the cross angle. By changing and fixing the support, it achieves multi-angle dual-polarization adjustment, making full use of the array spacing to realize space utilization and multi-scenario applications.

[0017] To address the need for different microwave frequency bands in through-wall radar scenarios, this design adopts a solution of adding PIN diodes at the edge slots. By switching the PIN diodes, different radiation areas can be selected, thereby achieving the effect of reconstructing the operating frequency. The operating frequency band can be supplemented or reselected according to the working scenario, which better meets the usage needs of radar measurement in various scenarios. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the present invention; Figure 2 This is a schematic diagram of the auxiliary support of the present invention; Figure 3 This is a simulation diagram of the Vivaldi antenna S11 in an embodiment of the present invention; Figure 4 This is a schematic diagram of a Vivaldi antenna with an outer frame in an embodiment of the present invention; Figure 5 This is a schematic diagram of the Vivaldi antenna with a toothed, segmented outer frame design in an embodiment of the present invention; Figure 6 This is a schematic diagram showing the clearance of the toothed cutting structure when the angle changes in an embodiment of the present invention; Figure 7 This is an antenna gain curve without an external frame in an embodiment of the present invention; Figure 8 This is an antenna gain curve diagram with an additional outer frame in an embodiment of the present invention.

[0019] Among them, 1. FR-4 dielectric substrate, 2. high-frequency radiating surface, 3. power supply port, 4. PIN diode, 5. metal connector, 6. low-frequency radiating surface, 7. first fixing plate, 8. second fixing plate, 9. snap-fit ​​plate, 10. card slot. Detailed Implementation

[0020] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] The present invention proposes an ultra-wideband dual-polarized angle and frequency reconfigurable Vivaldi antenna for a through-wall target detection system. The antenna covers a frequency range of 1 GHz to 5.5 GHz and has a shape consisting of two rectangular crosses. The antenna element dimensions are 110 mm * 100 mm * 0.8 mm. The structure of the proposed ultra-wideband dual-polarized and frequency reconfigurable Vivaldi antenna for a through-wall target detection system is as follows: Figure 1 As shown, the antenna includes two cross-shaped antenna elements. The antennas are cross-mounted by slots at both ends, and the radiating surface of the rear antenna is corrected using a metal connector 5. Both antenna elements include an FR-4 dielectric substrate 1, a high-frequency radiating surface 2, a feed port 3, a PIN diode 4, and a low-frequency radiating surface 6. The radiating surface of the antenna is composed of both a low-frequency and a high-frequency radiating surface, connected by a PIN diode. The switching on and off of the diode selects the antenna's operating frequency, thereby expanding the antenna's operating frequency band. Slots within the radiating surface reduce the antenna's radiating area, concentrating the current and improving gain to some extent. A feed port is located on the high-frequency radiating surface; an auxiliary support with selectable cross angles is provided at the cross-connection point of the two antenna elements. This design creates an ultra-wideband dual-polarization angle and frequency reconfigurable Vivaldi antenna.

[0022] The ultra-wideband dual-polarized angle and frequency reconfigurable Vivaldi antenna for through-wall target detection systems proposed in this invention splits the radiating surface of the unit antenna. When the antenna is operating, the majority of the high-frequency current is radiated from the high-frequency radiation region, with the remaining small portion propagating to the low-frequency radiation region. The opening width of the low-frequency region determines its low-frequency cutoff frequency, and this width is much larger than the wavelength corresponding to the high frequency. Therefore, the high-frequency current is significantly affected by surface waves in this region, thus affecting the antenna's end-firing capability. Cutting off the high and low frequency regions can effectively reduce this impact in scenarios where only the high-frequency region is used. Therefore, when designing the slot lines, the high-frequency radiation width allows for high-frequency energy concentration, while the low-frequency region can also be designed with a larger width to reduce the current termination effect.

[0023] After dividing the high-frequency and low-frequency radiating surfaces, a simple metal covering is not sufficient for connection. Instead, a connecting component capable of selectively switching current on and off is needed to link the two. Therefore, this invention uses a PIN diode, which is commonly used in microwave devices, for connection. The PIN diode acts as a switch in the design. When it is off, current will not flow into the lower-frequency radiating surface in the latter half, and the antenna will operate at a higher frequency. When it is on, the entire radiating surface can be used. At this time, the low-frequency cutoff frequency of the antenna is reduced, and the overall gain at high frequencies will also increase due to the increased antenna area.

[0024] This invention blunts the ordinary square slot at the cross-mounting position of the two antenna elements, and uses a semi-polygonal slot type at the junction. An auxiliary bracket is added to the antenna to select commonly used cross-angles. This structure switches the operating mode from only horizontal and vertical polarization to a mode that can select from multiple commonly used angles. When the radar system performs multiple scans, it prolongs the radar's operating time. Furthermore, the displacement error caused by the mechanical rotation of the single-polarization antenna must be corrected in subsequent digital processing. The structure of this invention sets the polarization cross-angle to a controllable state, which significantly reduces the workload of the system's backend and thus improves efficiency.

[0025] Auxiliary support structure such as Figure 2 As shown, it includes a first fixing plate 7, a second fixing plate 8, and a snap-fit ​​plate 9. The first fixing plate 7 and the second fixing plate 8 are rotatably connected at one end, and the snap-fit ​​plate 9 is rotatably provided at the other end of the first fixing plate 7. The second fixing plate 8 is provided with multiple slots 10. The snap-fit ​​plate 9 cooperates with the slots 10 to adjust the angle between the first fixing plate 7 and the second fixing plate 8. The first fixing plate and the second fixing plate are used to fix two antenna units respectively.

[0026] The segmented connection design proposed in this invention has excellent scalability. Without changing the original antenna size, it can effectively optimize the operating frequency band of existing Vivaldi antennas and achieve multi-segment frequency reconfiguration, enabling more flexible selection of the antenna's operating frequency. By increasing the number of segments on the antenna radiating surface and using PIN diodes, the reconfigurability of the Vivaldi antenna can be systematically expanded upwards.

[0027] Simulation results of the ultrawideband dual-polarization angle and frequency reconfigurable Vivaldi antenna proposed in this invention for a through-wall target detection system are as follows: Figure 3As shown, when the diode is turned on, the return loss S-parameter is less than -10dB in the range of 1.3GHz to 5.6GHz, indicating that the antenna has good broadband characteristics. At the same time, the two ports with different polarizations remain below -25dB in the operating frequency band, which proves that the design scheme is effective and can greatly reduce the area of ​​the planar helical antenna, achieving the goal of antenna miniaturization and ultra-wideband design.

[0028] To further improve the gain of the Vivaldi antenna, this embodiment includes an external frame structure around the antenna, such as... Figure 4 As shown, excluding the Vivaldi antenna body, its external cavity adopts a cylindrical horn-like outer frame design. This is intended to mimic and reproduce the constraint of the horn antenna's outer frame on the electromagnetic waves during antenna radiation. To adapt to the new outer frame, the Vivaldi antenna element has been partially cut off without affecting the original antenna performance, changing from a rectangle to a trapezoid. This structure provides excellent gain for the Vivaldi antenna to a certain extent and improves the directivity of the antenna pattern within its operating frequency band. Furthermore, it uses relatively thin copper sheets, resulting in a negligible impact on the overall weight of the antenna. Simulation comparisons show that the horn-like outer frame structure designed in this invention... Figures 6-7 The original antenna structure had a maximum gain of no more than 8dB. After using the new outer frame, the maximum gain was successfully increased to more than 9dB and the gain curve within the operating frequency band became more stable.

[0029] To accommodate the reconfigurable antenna polarization angle, the outer frame structure in this embodiment adopts a toothed, segmented design, such as... Figure 5 As shown, when changing the polarization angle, the antennas can make way for each other without affecting their original performance. Figure 6 The demonstration shows the clearance structure between the toothed outer cavities when the angle changes, which further improves the concentration of the antenna in terms of radiation pattern and gain, enabling it to work normally in dual-antenna mode.

[0030] The above embodiments are merely exemplary embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art can make various modifications or equivalent substitutions to the present invention within its scope and spirit, and such modifications or equivalent substitutions should also be considered to fall within the scope of protection of the present invention.

Claims

1. A miniaturized, ultra-wideband, dual-polarization angle and frequency reconfigurable Vivaldi antenna, characterized in that, The device includes two antenna units arranged in a cross shape. Each antenna unit includes a dielectric substrate, an antenna radiating surface, a feed port, and a PIN diode. The antenna radiating surface is divided into a high-frequency radiating surface and a low-frequency radiating surface. The high-frequency radiating surface and the low-frequency radiating surface are connected by a PIN diode. The operating frequency is selected by turning the PIN diode on and off. A feed port is provided on the high-frequency radiating surface. The two antenna units are provided with an auxiliary bracket at the cross-connection position, which allows for multiple cross-angle selection.

2. The miniaturized ultrawideband Vivaldi antenna with reconfigurable dual-polarization angle and frequency according to claim 1, characterized in that, The high-frequency radiation surface and the low-frequency radiation surface are designed with slots.

3. The miniaturized ultrawideband Vivaldi antenna with reconfigurable dual-polarization angle and frequency according to claim 1, characterized in that, The two antenna elements are inserted and placed through a polygonal passivated slot.

4. The miniaturized ultrawideband Vivaldi antenna with reconfigurable dual-polarization angle and frequency according to claim 1, characterized in that, After the two antenna elements are placed in a cross shape, the broken antenna radiating surface is corrected by a metal connector.

5. The miniaturized ultrawideband Vivaldi antenna with reconfigurable dual-polarization angle and frequency according to claim 1, characterized in that, The auxiliary bracket includes a first fixing plate, a second fixing plate, and a snap-fit ​​plate. The first fixing plate and the second fixing plate are rotatably connected at one end, and the snap-fit ​​plate is rotatably provided at the other end of the first fixing plate. The second fixing plate is provided with multiple slots. The snap-fit ​​plate cooperates with the slots to adjust the angle between the first fixing plate and the second fixing plate. The first fixing plate and the second fixing plate are used to fix two antenna units respectively.

6. The miniaturized ultrawideband Vivaldi antenna with reconfigurable dual-polarization angle and frequency according to claim 1, characterized in that, The two antenna units are provided with an external frame structure.

7. A miniaturized ultrawideband Vivaldi antenna with reconfigurable dual-polarization angle and frequency according to claim 6, characterized in that, The outer frame structure surrounds the antenna, and the shape of the outer frame structure is variable.

8. A miniaturized ultrawideband Vivaldi antenna with reconfigurable dual-polarization angle and frequency according to claim 7, characterized in that, The outer frame structure consists of multiple blocks, which are installed in a toothed, interlocking manner.

9. A miniaturized ultrawideband Vivaldi antenna with reconfigurable dual-polarization angle and frequency according to claim 6, characterized in that, The outer frame structure is made of copper sheet.

Images