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This paper presents a 6-bit phase shifter operating in the 11∼13 GHz band. The designed phase shifter is fabricated using a 130-nm SOI process to validate its performance. For fine phase adjustment, the phase shifter employs six single-bit phase shifters ranging from 5.625° to 180°. To expand the bandwidth and minimize the phase and gain errors, the 90° bit uses low-pass and high-pass filters. Additionally, the 180° bit uses a transformer-based switch structure. The fabricated phase shifter measures 0.87×0.4 mm², with a return loss of more than 10 dB, an average insertion loss of 6.41 dB, RMS phase errors ranging from 3.19° to 4.13°, and RMS gain errors between 0.52 dB and 0.56 dB. [ABSTRACT FROM AUTHOR]

This paper presents a Ka-band variable gain phase shifter with a non-linear DAC comprising an IQ generator, a pair of vector generators with a 180° phase difference, and a vector summation circuit. Non-linear DACs are used to simplify the phase control DACs and reduce phase errors. Between 29 GHz and 33 GHz, the insertion loss and total root mean square phase error are less than 5.02 dB and 1.71°, respectively. The device, which measured 0.259 mm² in size including the DACs, was fabricated using the 65-nm RF CMOS process. [ABSTRACT FROM AUTHOR]

This paper proposes a compact 4 × 4 Butler matrix (BM) with broadband characteristics within the 5G NR frequency range (3 GHz ~4.5 GHz). To achieve broadband performance, 3 dB broad-side coupler with optimal parameters was implemented, and the circuit was designed with a strip line based on the FR-4 four-layer structure to reduce the size. The average implementation loss was measured as −1.5 dB, and the reflection coefficient was measured as over 15 dB across the entire frequency range. Phase differences of −45°, 135°, −135°, and 45° were confirmed, with an average phase error of ±3°. When the antenna was mounted, beam steering angles were measured as 10.29° ± 1°, −32.41° ± 1.5°, 32.41° ± 1.1°, and −10.29° ± 2.5°. The size of the manufactured compact BM was 40×38.6×1.2 mm3, and it achieved a size reduction of 30% and a bandwidth improvement of 2.54 times compared with the legacy BM using the same frequency. Ansys HFSS was used to design and simulate the BM, and the results suggested that this wideband compact BM could be used for the miniaturization of 5G beamforming systems. [ABSTRACT FROM AUTHOR]

This paper presents a 6-bit phase shifter designed and fabricated using a 150-nm GaN HEMT process. The designed phase shifter operates in the n257 (26.5-29.5 GHz) band of the 5G NR standard, and the structure of a switched-filter phase shifter is used. The designed phase shifter connects six single-bit phase shifters in series from 180° to 5.625° to change the phase within the phase range of 360°. An LCL low-pass T-type filter is used to reduce the size of the filter element. The 180° phase shifter mixes low-pass and high-pass T-type filters. The fabricated phase shifter has an average insertion loss of 8.45 dB and an RMS phase error of less than 4.54° at 26.5-29.5 GHz. Herein, the phase shifter had a low insertion loss per bit and a small RMS phase error. [ABSTRACT FROM AUTHOR]

This study compares the designs of one-stage and two-stage reflection-type phase shifters for miniaturized S-band multi-functional transmit-array antennas. Both phase shifters have areas smaller than 0.2 λ0×0.4 λ0, which is less than half of the conventional unit cell size of 0.5λ λ0×0.5 λ0, and both phase shifters have a phase shifting range of more than 360°. The one-stage phase shifter requires a miniaturized hybrid coupler, 1/4 wavelength transmission line, and additional elements to implement a wide phase shifting range; hence, the phase shifter has a non-uniform insertion loss distribution and a peak insertion loss of 4.3 dB. The two-stage phase shifter outperformed the one-stage phase shifter; it had a relatively uniform insertion loss distribution of 2.5 dB because of its simple circuit structure. [ABSTRACT FROM AUTHOR]

In this study, miniaturized unit cell design and verification of multi-functional transmissive meta-surface for S-band radar are presented. The proposed unit cell comprises a receiver (Rx) antenna, a miniaturized reflection-type phase shifter, a PIN diode switch for polarization selection, and a dual-pol transmitter (Tx) antenna. The Rx/Tx antennas are stacked patch type antennas, and the reflection-type phase shifter, which has a smaller area of 36 % than a conventional hybrid coupler, controls the phase shifting from 0 to 330°. The PIN diode switch uses a −5 V reverse DC voltage bias to handle high input radio frequency (RF) power of 23 dBm. Moreover, a 1×2 unit cell array was fabricated to verify the unit cell performance. The array antenna freely converted polarized waves (horizontal/vertical) and exhibited beam steering performance in a range of approximately 50°. [ABSTRACT FROM AUTHOR]

In this work, we suggest a radar operation using overlap beamforming and present a wide-angle waveguide array antenna for implementation. First, we design a reduced-waveguide antenna to obtain wide-angle properties, and then we design a ridge-waveguide antenna to enlarge the beam-steering angle. At the designed center frequency of 9.375 GHz, the size of the ridge-waveguide antenna radiation aperture is 14 mm×8 mm, and a miniaturization rate of 48.2 % is obtained compared to the WR-90 standard waveguide. Using this scheme, a 1×8 array antenna was designed and manufactured. Consequently, the average beamwidth of the E-plane of each antenna was 120°, and the average beamwidth of the H-plane was 89.7°. For the beam-steering verification, several phase shifters corresponding to the beam-steering angles were fabricated, and it was confirmed that the beam-steering angle was consistent with the designed value via beam-steering measurements using the 1×8 array antenna. Accordingly, we confirmed that the miniaturized ridge-waveguide array antenna had characteristics suitable for wide-angle beam steering for a hexagonal array structure. [ABSTRACT FROM AUTHOR]

The Ku-band (12～18 GHz) is mainly used for long-range satellite communications and radar applications. Because the signal power is weak in a long-range communication, it is important to reduce the loss of the transmitter and receiver. In this paper, we propose a low-loss compact 4×4 Butler matrix structure that operates in the range of 15.7～16.7 GHz. To achieve low-loss characteristics, a low-loss transmission line was designed based on the suspended transmission line. To miniaturize the structure, the internal circuit of the Butler matrix was designed as a 100 Ω system, and the input/output stage was matched at 50 Ω. The size of the Butler matrix circuit manufactured through the optimized design was 45×22×2.3 mm. The insertion loss, isolation between terminals, and return loss of each terminal measured within the operating frequency band were 1.36 dB (including connector loss), 20.5 dB, and 15.3 dB, respectively, demonstrating a performance similar to that of the simulated performance. The proposed 4×4 Butler matrix can be utilized as a low-loss beam-switching circuit for a 1×4 linear array antenna. [ABSTRACT FROM AUTHOR]

In this paper, we describe an automatic calibration method and test results for a tile-type subarray consisting of a Tx phased-array antenna for Ku-band satellite communication. For array antenna calibration, the aperture electric field distribution, which is supported by the planar near-field measurement system, is used to minimize the phase variations across the array aperture. All the calibration procedures are performed automatically through interoperation between the planar near-field measurement system and array antenna control board. As conditions for ending the automatic calibration process, the far-field gain, beam width, and pointing direction can be used. The tile-type Tx phased-array antenna used for verification of the proposed method is an 8×8 array of microstrip patch antennas operating in the Ku band and having a phase shifter with 22.5° resolution. [ABSTRACT FROM AUTHOR]

In this paper, we describe the design and test results of a conformal Tx active phased-array antenna composed of planar subarrays. The designed Ku-band conformal Tx active phased-array antenna consists of 64 planar subarrays, which are arranged as an 8×8 microstrip patch array antenna, with a total of 4,096 antenna elements. A total of 4,096 core chips, including amplifiers and phase shifters with 4-bit resolution are used, and true time delay (TTD) devices of 100 ps resolution are located once every 4×4 subarrays to remove the beam squint phenomenon manifesting at the off-broadside beam pointing region. The designed conformal Tx active phased-array antenna was fabricated and tested. The results show that the designed system could be operated without any beam squint for wide-angle beam steering of ±60°, with a 1.5° beam width at 500 MHz operating bandwidth. In addition, the analysis and test results of the air-cooled structure designed for system operation are described briefly. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The design of a novel broadband 180° phase shifter, with the main transmission line length of λ/4, which is smaller than a conventional broadband 180° phase shifter with a main transmission line length of λ/2, is proposed in this study. The proposed compact broadband planar balun, consisting of the λ/4 broadband 180° phase shifter and a 3 dB Wilkinson power divider, is implemented on a single-layer PCB and its characteristics are measured. The impedance bandwidth with a return loss of more than 15 dB at the input port is 52.1 %(7.62~13 GHz), and the bandwidth of the phase differences between the two output ports within the phases 175° and 185° is 56.6 %(7.09~12.7 GHz). The characteristics of the λ/4 broadband planar balun implemented in this paper are similar to those of the conventional λ/2 broadband planar balun. The length of the λ/4 broadband planar balun is lesser than that of the conventional λ/2 broadband planar balun, thus reducing the overall size by more than 11.6 %. [ABSTRACT FROM AUTHOR]

In this paper, we describe the design, manufacture, and performance test results of a highly integrated tile-type Rx phased-array antenna for Ku-band satellite communication. The designed tile-type receive phased-array antenna is composed of three multilayer boards. The first board consists of 8×8 arrayed patch antennas and a core chip with a low-noise amplifier and phase shifters. The second board includes a true time delay(TTD) circuit to minimize the beam squint in the wide frequency band and amplifiers. The third board consists of circuits to control the phase shifters and TTD circuit in boards 1 and 2, respectively. The manufactured tile-type antenna has the size and weight of 33×96×96 mm3 and 250 g, respectively. The results of the electrical performance test of the antenna are that the antenna gain and beam width are 24 dBi and 12° at the center of the operating frequency in the Ku-band. Further, the beam squint performance is less than 1° when steering through 0° and 40° in the φ and θ directions, respectively. A conformal phased-array antenna can be produced for satellite communication in the Ku-band using the proposed tile antenna. [ABSTRACT FROM AUTHOR]

Herein, we show the design and fabrication of a serial-to-parallel converter (SPC) using the 0.25-μm GaAs pHEMT process. The serial-to-parallel converter is composed of four bits to control the four phase shifters used in the core chip. The SPC stores the received serial data signal to a register in the SPC and converts the stored data into the parallel data. Each converted output data can control four phase shifters. The size of the fabricated SPC is 1,200 × 480 μm2 and it uses two DC power supplies of 5 V and -3 V. The consumption current of each DC power supply is 7.1 mA for 5 V, and 2.1 mA for -3 V. [ABSTRACT FROM AUTHOR]

This paper presents a design study of a solid state power oscillator to replace the conventional magnetron. The operational conditions of a single-stage 300 W LDMOS power amplifier were fully characterized. The power module consisted of two amplifiers connected in parallel. A delay-line feedback loop was designed for self-oscillation. A phase shifter was inserted in the delay-line feedback loop for adjusting the round-trip phase. Experiments performed using the power oscillator showed an output power of 800 W and a DC-RF conversion efficiency of 58 % at 2.327 GHz. The measured results were in good agreement with those predicted by numerical simulations. [ABSTRACT FROM AUTHOR]