A periodically changing ultra-wideband phased array feed

Abstract

The present invention belongs to the field of antenna technology, and specifically is a periodically gradient ultra-wideband phased array feed. The ultra-wideband phased array feed of the present invention has a Vivaldi array antenna as its main body, which is composed of two Vivaldi antenna units with different unit widths and different bandwidths arranged in a certain way. The feed arrangement minimizes the number of units and reduces costs. Due to the ultra-wideband characteristics of the Vivaldi antenna array itself, the feed can achieve ultra-wideband operation. The feed uses a dense array to sample the focal plane field, which can enable the reflector antenna to achieve a higher aperture efficiency. The present invention can be used in a single reflector antenna system or a dual reflector antenna system to achieve ultra-wideband and high-efficiency operation of the reflector antenna.

Description

Technical Field

[0001] The invention belongs to the technical field of antennas, and in particular relates to an ultra-wideband phased array feed with gradual period variation. Background Art

[0002] Phased array antennas have been widely used in the fields of communications and radar due to their flexible beam agility and multi-beam capabilities. However, they are always faced with the pressure of high costs due to the need for a large number of back-end transmitting and receiving components. As the array gain required by the application scenario increases, it is inevitable to increase the array aperture, which is a physical limitation that is difficult to break through. Especially in deep space applications such as radio astronomy and satellite tracking, the required array aperture is huge. To construct a large array with a half-wavelength spacing of the operating frequency, the number of arrays will be tens of thousands. Therefore, in these fields, the most commonly used antennas are usually low-cost reflector antennas.

[0003] As the core electromagnetic wave receiving device of the reflector antenna, the feed source is similar to the retina of the human eye and has a crucial impact on the system performance. Traditional reflector antennas use an open horn placed near the focus of the reflector as a feed source. However, the radiation beam shape of the horn antenna changes gradually with the frequency. The change in beam width will seriously affect the efficiency of the reflector antenna, thereby affecting the working bandwidth of the system. A single feed source applied to a reflector antenna can only produce a single beam, which is inefficient when conducting deep space exploration. Although the feed group can generate multiple beams, the horns at the edge of the feed group are in an off-focus state, making it difficult to achieve good aperture field matching, and due to aperture limitations, the field of view of the multiple beams is discontinuous. Summary of the invention

[0004] In order to solve the deficiencies of the prior art, the present invention provides a periodically gradient Vivaldi phased array feed source, which can be used in a single reflector antenna system or a dual reflector antenna system to achieve ultra-wideband and high-efficiency operation of the reflector antenna.

[0005] The periodic gradient ultra-wideband phased array feed provided by the present invention has a Vivaldi array antenna as its main body, which is composed of two Vivaldi antenna units with different unit widths and different bandwidths arranged in a gradient periodic manner on a metal floor; wherein the antenna unit with a narrower width is a broadband unit, which can cover the entire frequency band from high frequency to low frequency, and the antenna unit with a wider width is a narrowband unit, which covers a lower frequency band; the broadband unit is located in the middle part of the array, and the narrowband unit is located in the outer circle of the array; the so-called "antenna units are arranged in a gradient periodic manner" means that the antenna units in the middle part of the array are arranged in a periodic manner with a small spacing, and the antenna units in the outer circle of the array are arranged in a periodic manner with a large spacing, and the array unit period changes gradually from the inside to the outside, and the outer circle unit spacing is twice the inner circle unit spacing. See Figure 1 shown.

[0006] In the present invention, the Vivaldi array antenna can be regarded as being composed of multiple columns of one-dimensional linear arrays, and each column of the linear array is composed of a different number of Vivaldi antenna units of two widths connected together.

[0007] In the present invention, the unit width (ie, spacing) of the narrowband unit is twice the unit width (ie, spacing) of the broadband unit, and the height and thickness of the two units are the same.

[0008] In the present invention, the Vivaldi antenna unit adopts an all-metal structure. The antenna consists of a radiation section in the upper part and a feeding section in the lower part. The radiation section is horn-shaped, and the feeding section is a type III balun processed integrally with the antenna. The antenna is externally excited through a coaxial connector connected to the balun.

[0009] In the present invention, the reflection cavity of the type III balun adopts an arc structure, and the opening angle of the arc is 30 degrees to 90 degrees.

[0010] In the present invention, the arc-shaped reflection cavity of the antenna balun is connected to the radiation end of the antenna through a two-wire transmission line.

[0011] In the present invention, the dual-wire transmission line portion of the balun adopts a slot structure with a gradually varying width, and the transmission line cooperates with the upwardly flipped arc-shaped reflection cavity, so that the coaxial connector can directly feed the antenna from the bottom of the antenna.

[0012] In the present invention, the metal floor is used to reflect electromagnetic waves, reduce backward radiation, and avoid mutual influence between rear-end electronic devices and front-end array antennas.

[0013] The Vivaldi antenna unit provided by the present invention not only enhances the rigidity of the antenna, but also can adopt a standard coaxial connector for feeding, thereby greatly reducing the processing cost and simplifying the installation process.

[0014] The phased array feed provided by the present invention maximizes the unit spacing and adopts a gradual periodic arrangement mode to minimize the number of units and reduce costs. Due to the ultra-wideband characteristics of the Vivaldi antenna array itself, the feed can achieve ultra-wideband operation. The feed uses a dense array to sample the focal plane field, which can enable the reflector antenna to achieve a higher aperture efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of the overall structure of the phased array feed.

[0016] Figure 2 The following are structural diagrams of Vivaldi antenna units with two different widths.

[0017] Figure 3 This is the back view of the phased array feed.

[0018] Figure 4For metal floor.

[0019] Figure 5 is the E-plane radiation pattern of the feed at a specified frequency.

[0020] Figure 6 is the H-plane radiation pattern of the feed at a specified frequency.

[0021] The numbers in the figure are: 1 is the one-dimensional linear array of Vivaldi antenna, 2 is the metal floor, 3 is the broadband Vivaldi antenna unit, 4 is the narrowband Vivaldi antenna unit, 5 is the width gradient slot, 6 is the arc reflection cavity, 7 is the coaxial feeding connector, 8 is the mounting bracket, 9 is the long screw, and 10 is the floor slit. DETAILED DESCRIPTION

[0022] like Figure 1 The figure shows the schematic diagram of the structure of the phased array feed source. The feed source is an all-metal structure. The main body is composed of multiple rows of Vivaldi antenna one-dimensional linear arrays 1. Each row of the linear array 1 is processed in an integrated manner using a CNC machine tool.

[0023] like Figure 2 As shown, there are a broadband Vivaldi antenna unit 3 and a narrowband Vivaldi antenna unit 4, and different numbers of units of two different widths are connected to form a linear array 1.

[0024] like Figure 3 As shown, after each row of linear arrays 1 is processed separately, it is inserted from the back of the metal floor 2 and limited to the position as shown in FIG. Figure 4 The floor slits 10 shown can be fixed by screws.

[0025] like Figure 3 As shown, the feed source mounting bracket 8 is fastened to the back of the metal floor 2 by long screws 9. The mounting bracket 8 can be used for testing and installing the feed source after threaded holes are opened.

[0026] Figure 4 The E-surface radiation pattern of the feed at a specific frequency point. The excitation amplitude and phase of each element of the feed are obtained using the conjugate matching method. It can be seen that the feed can have a consistent pattern in a wide operating frequency band. The pattern is highly symmetrical and concave in the center to compensate for the spatial loss of the feed irradiating the reflector antenna, which can achieve a higher aperture efficiency of the reflector antenna. Because the array is small at low frequencies, it can only intercept the energy of the first circular ring of the focal plane field, so the pattern is different.

[0027] Figure 5 is the H-surface radiation pattern of the feed source at a specific frequency point. It can be seen that Figure 4 The E-plane radiation patterns shown are almost the same, indicating that the feed radiation pattern has good circular symmetry.

Claims

1. A periodically variable ultra-wideband phased array feed, characterized in that: The main body is a Vivaldi array antenna, which consists of two Vivaldi antenna units of different widths and bandwidths arranged in a gradient periodic manner on a metal floor; among them, the antenna unit with a narrower width is a broadband unit, covering the entire frequency band from high frequency to low frequency, and the antenna unit with a wider width is a narrowband unit, covering the lower frequency band; the broadband unit is located in the middle of the array, and the narrowband unit is located in the outer circle of the array; the so-called "antenna units are arranged in a gradient periodic manner" means that the antenna units in the middle of the array are arranged in a periodic manner with a small spacing, and the antenna units in the outer circle of the array are arranged in a periodic manner with a large spacing. The array unit period changes gradually from the inside to the outside, and the outer circle unit spacing is twice the inner circle unit spacing; The Vivaldi array antenna is regarded as being composed of multiple columns of one-dimensional linear arrays, each column of the linear array being composed of a different number of Vivaldi antenna units of two widths connected together; The unit width of the narrowband unit is twice the unit width of the broadband unit, and the height and thickness of the two units are the same; The Vivaldi antenna unit adopts an all-metal structure. The antenna consists of a radiation section in the upper part and a feeding section in the lower part. The radiation section is horn-shaped, and the feeding section is a type III balun processed integrally with the antenna. The antenna is externally excited through a coaxial connector connected to the balun.

2. The periodically gradient ultra-wideband phased array feed according to claim 1, characterized in that: The reflection cavity of the type III balun adopts an arc structure, and the opening angle of the arc is 30 degrees to 90 degrees.

3. The periodically gradient ultra-wideband phased array feed according to claim 2, characterized in that: The arc-shaped reflection cavity of the third-type balun is connected to the radiation end of the antenna through a two-wire transmission line.

4. The periodically gradient ultra-wideband phased array feed according to claim 3, characterized in that: The dual-wire transmission line part adopts a slot structure with a gradually changing width. The transmission line cooperates with the upwardly flipped arc-shaped reflection cavity, so that the coaxial connector feeds the antenna directly from the bottom of the antenna.

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