1 Introduction
Because the microstrip antenna has the characteristics of low cross sections, light weight, easy processing, such antennas are increasing in military and civilian applications. In particular, the rapid development of SAR (synthetic aperture radar) technology has put forward a growing requirements for microstrip antennas. I hope to get broadband, large scan angle, high efficiency and low cross-crossing on one antenna. The performance of the chemical, and has a simple feeding, easy to integrate feed system integration.
There are a variety of feed modes of microstrip patch antennas, which is the most simple structure in the form of microstrip lines, and it is easy to implement integrated design with feed networks at the same time. The microstrip-feed rectangular microstrip table is one of the most widely used microstrip units since the report. However, this rectangular microstrip antenna uses a single layer form, the bandwidth is very narrow (usually. 1881.3%), and the feed position is limited to the radiation side. Subsequently, domestic and foreign science and technology workers have made a lot of research on various rectangular microstrip antennas. In order to show wide working bandwidth, a double-layer microstrip table antenna of radiation edge feed is introduced. The lower patch is a feeder, the upper conductor patch is parasitic, and the medium layer of low dielectric constant in the middle of the two layers. This structure uses a double resonant to show wide working frequency band, which is about 10% of the working bandwidth of this antenna.
The single-layer rectangular patch antenna of a non-radiating co-feeding is taken first, and when the unit is used for microstrip co-feed array antenna design, the length of the feed line can be shorter, and the design of the feed network is simplified. Therefore, it can be used as the design of the high-efficiency microstrip array antenna, but is narrow as the normal single-layer rectangular microstrip antenna. Recently, a cross-polarization suppression technique for the radiation edge feed double-layer rectangular microstrip antenna is provided. The method is on, and the lower radiation patch simultaneously opens 4 or more gaps, orientation and antenna of the gap. The polarization direction is consistent, and the intersective mode current reaches the intersection of the antenna unit.
The various techniques described above are introduced herein, a new type of double-layer microstrip tableting antenna of non-radiative edge feed, and the performance characteristics of the antenna and their application in the array have been studied.
2 unit structure and simulation test results
The structure composition of the antenna unit is shown in Figure 1. In order to achieve the same structure in which the broadband operation is used, the entire antenna is mainly mainly by the feed microstrip layer, the foam layer, the parasitic microstrip layer and the ground structure. The plate is partially composed. The feed patch is etched on the feed microproerator, etching a parasitic patch on the parasitic microstrip board, and the parasitic tab is used in the chart.
Unlike traditional bilateral microstrip patches, the underlying rectangular patch uses microstrip wireless side feed, the advantage of using such feed is the design of the feed network, but with The problem is that the antenna except for the primary model TM01 model will also energize the TM10 cross-polarization mold, which will worsen the cross-polarization performance of the antenna. For single-layer rectangular microstrip patches, document [3] proposes to suppress TM10 model by selecting the aspect ratio (1.5: 1) of the appropriate rectangular patch. However, the simulation results of HFSS indicate that the long-width of the simple adjustment of the patch is limited, although the inner cross-polarization of the band is up to -10DB, although the band is reached from -10dB, although the inner cross-polarization of the long-range (1.5: 1) is up to -10dB; At this time, the antenna has a lower radiation impedance, and the broadband impedance is difficult. In order to solve the above problems, in addition to properly controlling the aspect ratio of the rectangular patch, the parasitic patch is also opened in the direction perpendicular to the radiation side, and the surface current of the cross-polarization mode is opened. To achieve the purpose of suppressing the intersective mode of the antenna. The simulation results show that when the number of gaps in the uniform distribution reaches more than 3 or more, and LS ≥ 0.8W2, the intersection of the antenna tends to stabilize.
In order to verify the results of the above studies, use the HFSS optimization design results, and the non-radiative feed double-layer microstrip antenna unit of X-band is designed according to the following parameters: ER1 = 2.94, H1 = 0.508mm; ER2 = 1.07, H2 = 3.0 MM; ER3 = 4.39, H3 = 0.254 mm;
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A) cross-sectional view
B) Feed microproof board circuit diagram
C) Parasitic microprolating board circuit diagram
W1 = 8.7mm, L1 = 9.7 mm; W2 = 9.2mm, L2 = 11.3 mm; WS = 0.5mm, LS = 7.7mm. The test results of the antenna showed that it was in 15.5% of the bandwidth VSWR ≤ 1.2, the cross-polarization of the inner two main surfaces was better than -16dB, and Figure 2 gave the simulation and test results of the port standing wave curve, both of them. Agree. It can be seen that relatively general double microstrip patches, the novel unit of impedance bandwidth is 3-5%, while cross-polarization indicators are comparable.
Figure 2 Simulation and test results of unit stand wave characteristics
Application of 3 Antenna Unit in Array Design
The new two-layer patch antenna unit proposed above can be flexibly applied to the design of broadband coplanarcasting microstrip array antennas, and a two-layer microstrip unit, a new antenna with respect to conventional radiation edge feed The unit can simplify the feed circuit of the antenna array, improve the feed efficiency, easy to achieve broadband, efficient coplanar feeder array;, especially when applied to the microstrip line array design, it is conducive to save feeds, easy to design the large sweep angle Antenna array. Figure 3 shows a comparison diagram of various type array modes of two microstrip patch cells.
A. Radial edge feed B. Non-radiation edge feed
Figure 3 Comparison of group array modes of two microstrip units
The X-band 8 × 8 microstrip antenna experimental wavelength in this new antenna unit is used, and the fed circuit of the waveform and the actual photo are composed of 8 1 × 8 microstrip line arrays. The units such as each unit in the array are inquiry, and each line source is fed using a T / R component, and a scan of one-dimensional ± 25 ° can be used to suppress the cross-polarization of the antenna, between adjacent lines. Using a mirror arrangement, the feed is inverted to each other. The microwave dark room was tested on this non-pistontic technical index. The results show that the residential wave ratio of each linear array in the frequency band is excellent in 1.6, and the cross-polarization of the entire vestor is better than -30db. The sub-valve level is superior to -11dB, the inner antenna efficiency is superior to 70%, and Fig. 5 and Fig. 6 give the port standing wave measured curve and the test result of the typical direction map of the line array. It can be seen from these results to show good performance indicators in a wide frequency band.
(A) feed circuit
(B) Real photo
Figure 4 X-band 8 × 8 unit antenna small array schematic
Figure 5 Port standing wave test curve of each line array in each of the 8 × 8 small array
Figure 6 Typical direction map of the direction of the direction of the line array
4 Conclusion
Simulation and experimental results show that the non-radiative double-layer microstrip tablet has a good broadband operating ability, and when it is applied to the design of a coplanar, it can simplify the airfoil of the antenna array. Electric circuit, improve feed efficiency, easy to achieve broadband, efficient coplanar feeder array; especially when applied to microstrip line array design, it is conducive to saving feeding space to facilitate design of the antenna array of large sweep angles. The antenna unit can be foreseen that the radar and communication system have broad application prospects.
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Source: Wiku Electronic Market Network
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