Design of Beamforming Scheme Using Single RF Chain Based on SPA Antenna

Direction finding is a traditional technique that was initially used in radio surveillance. Since its inception, antenna-based direction finding technology has become the core technology in various fields, such as radar(to find the direction of the target) and mobile communication(where MIMO-based multi-antennas are used). Moreover, use of the direction finding technology in the field of IoT, such as in Bluetooth, is increasing. Thus, the importance of direction finding technology is growing in various fields. However, it continues to be treated as a sub-technology of radio surveillance, radar, and wireless communication. The aim of this paper is to help readers systematically understand direction finding technology. Accordingly, a systematic classification and analysis of each characteristic of direction finding technology, along with recent research and development trends for it, are discussed in the paper.

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Direction Finding Technology: Tutorial, Review, and Research Prospects

Jang¹

2019

Four-Beam Direction Finding Using Two-Element Monopulse Antenna and I/Q Demodulator

Jang¹

2019

In general, a direction finding system based on array antennas is implemented using a digital beamforming method with the same number of receivers as antennas, or using an RF beamforming method where a single receiver has a plurality of phase shifters. However, both approaches require complicated hardware configurations, which is a major disadvantage. In this paper, we propose a new method to generate 4-beam patterns using only two antennas and a single receiver with a sum and difference pattern of 180° hybrid, and the orthogonality of an I/Q demodulator. To verify the proposed method, we applied it to a Bluetooth direction finding system. The simulation results demonstrated that it is possible to implement an effective direction finding system using the proposed method.

Transmit Diversity with Single Transmitter Using Switch and 180° Hybrid

Yoon¹,

Jang²

2020

Generally, two synchronized transmitters are required to implement transmit diversity, such as Alamouti codes. However, because two transmitters are used, many disadvantages arise, such as increased price, power consumption, complexity, and the necessity of synchronization and calibration. In this paper, we proposed a new method to realize transmit diversity only using one transmitter. The proposed method combines baseband signal processing and an RF circuit, which connects a 180° hybrid and one switch between one transmitter and two transmit antennas, and controls the switch at the mid-point of the transmission bit. Because the proposed system has only one transmitter, the power consumption and hardware cost can be reduced by half, and the diversity gain can be realized in a fading environment. We verified the feasibility of the proposed method by computer simulations and confirmed that diversity operation can be realized using hardware.