A. V. Ananyev – Ph.D. (Eng.), Associate Professor, Air Force Academy n.a. professor N.E. Zhukovsky and Y.A. Gagarin

(Voronezh)

E-mail: sasha303_75@mail.ru

A. N. Katrusha – Ph.D. (Eng.), Associate Professor, Air Force Academy n.a. professor N.E. Zhukovsky and Y.A. Gagarin (Voronezh)

A. V. Gorovoj – Engineer, Scientific-Production Enterprise «New Telecommunication Technologies» (Saint-Petersburg) E. A. Ivanov – Engineer, Scientific-Production Enterprise «New Telecommunication Technologies» (Saint-Petersburg)

In the previous articles, the authors carried out theoretical calculations and computer simulation of parameters of a contour magnetic antenna with the possibility of radiation from an unmanned aerial vehicle (UAV). One of the problems when using such narrow-band magnetic antennas on UAVs is providing of matching characteristics in the receiving-transmitting path. One of the matching parameters is the standing wave ratio (SWR). The setting of the antenna SWR is sensitive to changing weather conditions, electromagnetic environment.

The known technical solutions brought to practical implementation and presented in the open press and the Internet are not applicable for use on UAVs. The purpose of this article is to develop a device for automatic adjustment of SWR of a contour magnetic antenna of an unmanned aerial vehicle, which reconfigures the antenna to a previously unknown frequency in the real time.

The article describes the algorithm for auto-tuning the standing-wave ratio of a magnetic antenna using a microcontroller that controls the servo drive, which in turn transmits torque to the rotor of the air condenser built into the external loop of the magnetic antenna. The logic of work is as follows:

1. The working frequency of the radio channel of the onboard UAV radio transmission equipment is set.
2. The exciting voltage of the carrier frequency is applied to the output stages connected in the internal loop of the antenna magnetic coupling.
3. The voltage value of an incident wave and a reflected wave is measured.
4. Measurement of the SWR value is performed on the microcontroller according to readings taken.
5. The microcontroller sends a PWM signal which rotates the rotor of the air capacitor and this leads to the antenna tuning to the operating frequency.

The article also presents the research results of the developed device. The layout included: 1) auto-tuning circuit with the antenna; 2) signal generator R&S SMBV100A; 3) signal analyzer R&S FSH8; 4) computer. During the test, the characteristics of the layout have been obtained, such as: 1) tuning time from one edge of the range to another one (the worst case); 2) the SWR value in the operating range; 3) bandwidth in the operating range; 4) dependence of the PWM step on the tuning frequency. Comparison of the characteristics of the given layout with the results described in the previous articles of the authors has been carried out.

1. Katrusha A.N., Anan'ev A.V. Sravnitel'naya otsenka vozmozhnostey radiosvyazi s bespilotnymi letatel'nymi apparatami v diapazonakh KV i UKV dlya poluzakrytykh i zakrytykh trass rasprostraneniya radiovoln // T-Comm: Telekommunikatsii i transport. 2017. № 10. S. 4–9.
2. Katrusha A.N., Anan'ev A.V. Konturnaya antenna DKMV diapazona dlya bespilotnykh letatel'nykh apparatov // Antenny. 2017. № 8. S. 45–52.
3. Anan'ev A.V., Katrusha A.N. Eksperimental'naya razrabotka vneshnikh DKMV magnitnykh antenn bespilotnykh letatel'nykh apparatov maloy dal'nosti // Zhurnal radioelektroniki [Elektronnyy zhurnal]. 2017. № 11. URL: http://jre.cplire.ru/jre/nov17/7/text.pdf.
4. Goncharenko I.V. Antenny KV i UKV. M.: Radiosoft. 2016.
5. Avtomaticheskiy antennyy tyuner KV-transivera [Elektronnyy resurs] / URL: http://ur4qbp.ucoz.ua/publ/3-1-0-18 (data obrashcheniya: 22.07.2018).