The waveguide-slot element is widely used in navigation devices, radar, and remote sensing of the Earth [1]. Technologies of automated guided vehicles are currently being developed [2-3]. And in this technology, a waveguide-slot element can be used as an antenna. Therefore, consideration of such a radiating structure is relevant.
A mathematical model of a waveguide-slot element consisting of four elements on a wide wall of the waveguide was constructed using the finite difference method. This type of emitting element is in-phase. The radiation direction coincides with the normal to the longitudinal axis of the antenna. In-phase excitation of the longitudinal slits is achieved by arranging the elements of the antenna array on different sides relative to the middle line at a distance λwg/ 2. Synchronization is provided due to an additional phase shift of 1800 due to the opposite direction of transverse currents. In fig. 1 presents a resonant waveguide-slot element.
According to the results of mathematical modeling, the following characteristics of the waveguide-slit element were obtained:
а) radiation pattern of the waveguide-slot element in the E and H planes (fig. 2);
б) dependence of parameter S11 on frequency (fig. 3).
In fig. 2 shows the directional pattern in the E and H planes of the waveguide-slit antenna array consisting of four slotsFrom fig. 2, it can be seen that the directional pattern has one main lobe, and the level of the side lobes does not exceed the level of -13 dB.
In fig. 3 shows the frequency dependence of the reflection coefficient (parameter S11) of the resonant waveguide-slit antenna array of four elements.
From fig. 3, it can be concluded that the minimum of the reflection coefficient is at the specified frequency of 9.375 GHz. A resonant antenna can be well matched to the feed line, but this matching is observed over a narrow frequency band. This phenomenon is because each slit is not individually aligned with the waveguide, which means that all waves reflected from the slots are in phase at the input of the antenna. All this leads to an increase in the value of the modulus of the reflection coefficient. The bandwidth at the reflection coefficient level of -15 dB is 900 MHz.
Optimization of the geometric dimensions of the location of the slots was carried out. Behind the openings, the place where the slots are removed should be 8.07 mm at the edge of the narrow wall, and the distance between the slots should be 22.227 mm. Optimization of the geometric dimensions of the location of the slots was carried out and showed that improvements in the performance of the antenna can be achieved by changing the location of the slot to 8 mm (optimal value) and correspondingly changing the distance between the elements is up to 22.12 mm (optimal value).
References
1. Manual of digital Earth / un. the g. e. of G. Huadong, G. Michael, A. Alessandro. Singapore: Springer Nature, 2020. 852 p. doi: 10.1007/978-981-32-9915-3
2. Smart Manufacturing: past research, present findings, and future directions / Kang H. S., Lee J. Y., Choi S. S. et all. International Journal of Precision Engineering and Manufacturing-Green Technology. 2016. Vol. 3, No. 1, pp. 111-128. doi: 10.1007/s40684-016-0015-5
3. Shin K.-Y., Park H.-C. Smart Manufacturing systems engineering for designing smart product-quality monitoring system in the Industry 4.0. IEEE 19th International Conference on Control, Automation and Systems (ICCAS): proceedings. 2019. pp. 1693–1698. doi: 10.23919/ICCAS47443.2019.8971667
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