A complementary cardioid ultra-wideband circularly polarized antenna element and array thereof

Abstract

The application discloses a complementary heart-shaped ultra-wideband circularly polarized antenna unit and an array thereof, and the antenna unit comprises a dielectric substrate, a heart-shaped patch, a ground with a heart-shaped slot and a microstrip line for feeding; the heart-shaped patch and the microstrip line for feeding are connected and arranged on one side of the dielectric substrate, and the ground with the heart-shaped slot is arranged on the other side of the dielectric substrate; the array comprises n complementary heart-shaped ultra-wideband circularly polarized antenna units, the antenna units are sequentially arranged with a rotation of 90 degrees in structure, the amplitudes of input signals of each antenna unit are equal, and the phases of the input signals of each antenna unit are sequentially rotated with a phase difference of 90 degrees between adjacent ports. The application adopts a heart-shaped complementary structure, realizes geometric perturbation through the natural concave of the center tip of the heart-shaped structure, and realizes an ultra-wide axial ratio bandwidth through single-point feeding of the antenna unit; and multi-point feeding is used for the antenna array, so that a wider working bandwidth can be realized.

Description

Technical Field

[0001] This invention relates to the field of antenna technology, and in particular to a complementary cardioid ultrawideband circularly polarized antenna element and its array. Background Technology

[0002] In modern wireless communication, satellite communication, radar systems, and navigation systems, circularly polarized antennas are widely used due to their advantages such as resistance to multipath fading and improved system sensitivity and capacity. Circularly polarized antennas with broadband or ultra-wideband capabilities, good polarization performance, and lightweight design have always been a hot topic in antenna research. Microstrip circularly polarized antenna elements or arrays can achieve signal input using single-point feeding and dual-point feeding schemes. When using single-point feeding for an element antenna, geometric perturbations are typically performed on the metal patch structure by chamfering corners, slotting the surface, and adding tuning stubs. The advantage is that it does not require an external power divider or phase shift network, but its significant disadvantage is narrow bandwidth and poor polarization characteristics. Multi-point feeding schemes require an external feeding network. The advantages are improved VSWR bandwidth and axial ratio bandwidth, but the disadvantages are complex feeding networks and larger size. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a complementary cardioid ultrawideband circularly polarized antenna element and its array. The cardioid complementary structure is adopted, and geometric perturbation is achieved through the natural concavity of the center tip of the cardioid structure. The antenna element can achieve an ultrawide axial ratio bandwidth by using single-point feeding. By using multi-point feeding for the antenna array, an even wider operating bandwidth can be achieved.

[0004] To solve the above-mentioned technical problems, the present invention provides a complementary cardioid ultrawideband circularly polarized antenna element, comprising: a dielectric substrate, a cardioid patch, a ground plane with a cardioid slot, and a microstrip line for feeding; the cardioid patch and the microstrip line for feeding are connected and are both disposed on one side of the dielectric substrate, and the ground plane with the cardioid slot is disposed on the other side of the dielectric substrate.

[0005] Preferably, the unit antenna radiates bidirectionally, with the electromagnetic waves radiated by the antenna perpendicular to one side of the heart-shaped patch being left-hand circularly polarized; the electromagnetic waves radiated by the antenna perpendicular to the ground side of the heart-shaped gap are right-hand circularly polarized.

[0006] A complementary cardioid ultrawideband circularly polarized antenna array includes: n complementary cardioid ultrawideband circularly polarized antenna elements, which are arranged in a 90-degree rotation in sequence. The input signals of each antenna element have equal amplitude and phase, and there is a 90-degree phase difference between adjacent ports.

[0007] Preferably, the electromagnetic waves radiated by the antenna are left-hand circularly polarized on the side perpendicular to the heart-shaped patch and right-hand circularly polarized on the side perpendicular to the ground of the heart-shaped slot.

[0008] Preferably, a reflective ground plane is placed at a certain distance on one side of the heart-shaped slot of the antenna, and the electromagnetic waves generated by the antenna are left-hand circularly polarized and radiate unidirectionally to the side perpendicular to the heart-shaped patch.

[0009] The beneficial effects of this invention are as follows: by adopting a cardioid complementary structure, geometric perturbation is achieved through the natural concavity of the center tip of the cardioid structure; the antenna element can achieve an ultra-wide axial ratio bandwidth by using single-point feeding; and by using multi-point feeding for the antenna array, an even wider operating bandwidth can be achieved. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the complementary cardioid ultrawideband circularly polarized antenna element of the present invention.

[0011] Figure 2 This is a schematic diagram of the reflection coefficient of the complementary cardioid ultrawideband circularly polarized antenna element of the present invention.

[0012] Figure 3 This is a schematic diagram of the axial ratio of the complementary cardioid ultrawideband circularly polarized antenna element of the present invention.

[0013] Figure 4 This is a schematic diagram showing the gain of the complementary cardioid ultrawideband circularly polarized antenna element of the present invention.

[0014] Figure 5 This is the radiation pattern of the complementary cardioid ultrawideband circularly polarized antenna element of the present invention.

[0015] Figure 6 This is a schematic diagram of the bidirectional radiative complementary cardioid ultrawideband circularly polarized array of the present invention.

[0016] Figure 7 This is a schematic diagram of the axial ratio of the bidirectional radiative complementary cardioid ultrawideband circularly polarized array of the present invention.

[0017] Figure 8 This is a schematic diagram showing the gain of the bidirectional radiative complementary cardioid ultrawideband circularly polarized array of the present invention.

[0018] Figure 9 This is the radiation pattern of the bidirectional radiation complementary cardioid ultrawideband circularly polarized array of the present invention.

[0019] Figure 10 This is a schematic diagram of the unidirectional radiative complementary cardioid ultrawideband circularly polarized array of the present invention.

[0020] Figure 11 This is a schematic diagram of the axial ratio of the unidirectional radiative complementary cardioid ultrawideband circularly polarized array of the present invention.

[0021] Figure 12 This is a schematic diagram showing the gain of the unidirectional radiative complementary cardioid ultrawideband circularly polarized array of the present invention.

[0022] Figure 13 This is the radiation pattern of the unidirectional radiation complementary cardioid ultrawideband circularly polarized array of the present invention. Detailed Implementation

[0023] like Figure 1 The complementary cardioid ultrawideband circularly polarized antenna element shown includes: a dielectric substrate 1, a cardioid patch 2, a microstrip feed line 3, and a ground plane 4 with a cardioid slot. Figure 1 The upper part is a 3D view of the antenna. The cardioid patch 2 and the microstrip feed line 3 are connected together and placed on the upper side of the dielectric substrate 1. The ground plane 4 with a cardioid slot is placed on the lower side of the dielectric substrate 1. The specific dimensions are marked on the diagram. Figure 1 The lower half; the relative permittivity and thickness of the dielectric substrate, as well as the specific dimensions of the radiating patch and ground plane, are determined according to the operating frequency. In this embodiment, the structural dimensions are: L = 40mm, P... x =25.3mm,P y =127mm, t=0.5mm, W f =1.5mm,P f =9.5mm,P sx =19mm,P sy =12.53mm; The equations of the heart-shaped lines for the heart-shaped patch and the heart-shaped gap are determined by formula (1):

[0024]

[0025] The coefficients a and b determine the size of the heart shape and the depth of the apex, θ∈[0,2π]. In this example: the heart-shaped patch is selected with a=8mm and b=1.65, and the heart-shaped gap is selected with a=13mm and b=1.65.

[0026] Figure 2 The reflection coefficient |S| of the complementary cardioid broadband circularly polarized antenna element in Embodiment 1 of this example is... 11 As can be seen from the figure, the antenna has a very wide impedance bandwidth. 11 The lowest frequency with a value less than -10dB is 2.4GHz, and the highest frequency is greater than 12GHz.

[0027] Figure 3 These are the axial ratio parameters of the complementary cardioid broadband circularly polarized antenna element in Embodiment 1. As can be seen from the figure, perpendicular to the cardioid patch side, the antenna emits a left-hand circularly polarized wave, with a bandwidth covering the frequency range of 2.34-6.24 GHz for an axial ratio AR < 3 dB; perpendicular to the cardioid slot side, the antenna emits a right-hand circularly polarized wave, with a bandwidth covering the frequency range of 2.34-6.55 GHz for an axial ratio AR < 3 dB. |S 11The operating frequency band that satisfies both -10dB and AR < 3dB is 2.34-6.24GHz, which means that an ultra-wideband circularly polarized operating frequency band has been achieved.

[0028] Figure 4 The figure shows the gain curve of the complementary cardioid broadband circularly polarized antenna element in Embodiment 1. As can be seen from the figure, the maximum gain of the two circularly polarized waves with opposite rotation directions is about 4dBi, and the gain is between 1dBi and 4dBi in the frequency range of 2.2-6.2GHz. The cross-polarization ratio is greater than 15dB in the frequency range of 2.4-6.5. The cross-polarization ratio here is the difference between the gains of two circularly polarized waves with opposite rotation directions in the same direction.

[0029] Figure 5 The radiation pattern of the complementary cardioid broadband circularly polarized antenna element in Embodiment 1 is shown, with three frequencies of 2.5 GHz, 4 GHz, and 6 GHz. As can be seen from the figure, the electromagnetic wave radiated on the cardioid patch side (+z axis) is a left-hand circularly polarized wave, while the electromagnetic wave radiated on the cardioid slot side (-z axis) is a right-hand circularly polarized wave. The radiation pattern is stable within the operating frequency band.

[0030] Figure 6 This is a schematic diagram of a bidirectional radiating complementary cardioid ultrawideband circularly polarized array according to Embodiment 2 of the present invention. The complementary cardioid broadband circularly polarized antenna elements are arranged by rotating 90 degrees sequentially to form a 2×2 array. The input ports of the four elements are represented by P1, P2, P3, and P4, respectively. When a signal is applied, the amplitude of the input signal in each antenna element is equal, and the phase is rotated sequentially. There is a 90-degree phase difference between adjacent ports. That is, assuming the phase of the input signal at port P1 is 0 degrees, the phases at ports P2, P3, and P4 are -90 degrees, -180 degrees, and -270 degrees, respectively.

[0031] Figure 7 The axial ratio of the bidirectional radiating complementary cardioid ultrawideband circularly polarized array in Embodiment 2 of the present invention is shown in the results. It can be seen that the axial ratios of the left-hand circular polarization and the right-hand circular polarization are basically the same in the 2-8 GHz frequency band and are both less than 1 dB, indicating excellent circular polarization performance.

[0032] Figure 8 The figure shows the gain of the bidirectional radiating complementary cardioid ultrawideband circularly polarized array in Embodiment 2 of the present invention. As can be seen from the figure, the maximum gain of the two circularly polarized waves is increased to about 9 dBi, and the gain is between 6 dBi and 9 dBi in the frequency range of 3-7.5 GHz. The cross-polarization ratio is greater than 30 dB in the frequency range of 2-8 GHz, and even greater than 50 dB in the frequency range of 3.8-6.3 GHz. Compared with the antenna element, the gain and cross-polarization ratio performance are significantly improved.

[0033] Figure 9The radiation pattern of the bidirectional radiation complementary cardioid ultrawideband circularly polarized array in Embodiment 2 of the present invention is shown. The three frequencies of 3GHz, 5GHz and 7GHz are drawn respectively. It can be seen from the figure that the electromagnetic wave radiated on one side of the cardioid patch is a left-hand circularly polarized wave, while the electromagnetic wave radiated on the side of the cardioid gap is a right-hand circularly polarized wave. The radiation pattern is stable within the operating frequency band.

[0034] Figure 10 The diagram illustrates three examples of unidirectional radiating complementary cardioid ultrawideband circularly polarized arrays according to the present invention. On the side of the cardioid gap of the bidirectional radiating complementary cardioid ultrawideband circularly polarized array, a metal anti-ground plate is added. The metal reflector reflects the right-hand circularly polarized wave propagating in the -z direction. The reflected electromagnetic wave propagates in the +z direction and the rotation direction is reversed to become a left-hand circularly polarized wave. By selecting a distance S1, the two left-hand circularly polarized waves can be superimposed to increase the antenna gain.

[0035] Figure 11 The axial ratio of the unidirectional radiating complementary cardioid ultrawideband circularly polarized array in Embodiment 3 of the present invention is shown in the results. It can be seen that the axial ratios of the left-hand circular polarization and the right-hand circular polarization are basically the same in the 2-8 GHz frequency band and are both less than 1 dB, indicating excellent circular polarization performance.

[0036] Figure 12 The figure shows the gain of the unidirectional radiating complementary cardioid ultrawideband circularly polarized array in Embodiment 3 of the present invention. As can be seen from the figure, the maximum gain of the antenna is further improved to about 13 dBi, and the gain is greater than 7.5 dBi in the frequency range of 2-7.2 GHz; the cross-polarization ratio is greater than 50 dB in the frequency range of 3-7.5 GHz; compared with the bidirectional radiating complementary cardioid ultrawideband circularly polarized array, the gain and cross-polarization ratio performance are further improved.

[0037] Figure 13 The radiation pattern of the unidirectional complementary cardioid ultrawideband circularly polarized array in Embodiment 3 of this invention is shown. The three frequencies of 3GHz, 5GHz and 7GHz are drawn respectively. It can be seen from the figure that the antenna radiates electromagnetic waves along the +z direction, mainly left-hand circularly polarized waves, and the radiation pattern is stable in the operating frequency band.

Claims

1. A complementary cardioid ultrawideband circularly polarized antenna element, characterized in that, include: The system comprises a dielectric substrate, a heart-shaped patch, a ground plane with heart-shaped slots, and a microstrip line for power feeding. The heart-shaped patch and the microstrip line for power feeding are connected and both are located on one side of the dielectric substrate. The microstrip line for power feeding is located on the side of the heart-shaped patch, and the ground plane with heart-shaped slots is located on the other side of the dielectric substrate. The equations for the heart-shaped patch and the heart-shaped line of the heart-shaped slots are given by formula... It is determined that the coefficients a and b determine the size of the heart shape and the depth of the cusp. Geometric perturbation is achieved through the natural indentation of the central apex of the heart-shaped structure; the antenna element radiates bidirectionally, with the electromagnetic wave radiated on the heart-shaped patch side (+z axis direction) being a left-hand circularly polarized wave, and on the heart-shaped slot side (-z axis direction) being a right-hand circularly polarized wave.

2. A complementary cardioid ultrawideband circularly polarized antenna array, characterized in that, include: n complementary cardioid ultrawideband circularly polarized antenna elements as described in claim 1, wherein the antenna elements are arranged in a 90-degree sequential rotation in structure, and the input signal amplitude of each antenna element is equal, the phase is rotated sequentially, and there is a 90-degree phase difference between adjacent ports; on the cardioid patch side, i.e. in the +z axis direction, the radiated electromagnetic wave is a left-hand circularly polarized wave, while on the cardioid slot side, i.e. in the -z axis direction, the radiated electromagnetic wave is a right-hand circularly polarized wave.

3. The complementary cardioid ultrawideband circularly polarized antenna array as described in claim 2, characterized in that, A reflective ground plane is placed at a certain distance from one side of the heart-shaped slot of the antenna unit. The electromagnetic waves generated by the antenna unit are left-hand circularly polarized and radiate unidirectionally to the side perpendicular to the heart-shaped patch.

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