Zero-Static-Power Beamforming Antenna Array Enabled by RF Memristive Switches

Zero-Static-Power Beamforming Antenna Array Enabled by RF Memristive Switches Xiaoyu. Xiao (1), Ziqi. Ren (1), Yifan Zhang (1),Tianyu Qu, Zhirun Hu(1) (1) Department of Electrical and Electronics, University of Manchester, UK ([email protected]) Abstract—This research investigates the development of a beamforming antenna array leveraging RF memristive switch technology to achieve zero static power consumption. By integrating RF memristors within the antenna array architecture, the proposed design aims to minimize energy consumption while ensuring high performance for advanced wireless communication systems. The study encompasses rigorous theoretical analysis, comprehensive simulations, and the hardware implementation of critical components such as phase shifters and couplers based on RF memristive switches. The resulting antenna array, operating efficiently at 2.4 GHz, demonstrates robust beamforming capabilities tailored to the demands of next-generation communication systems, including 5G and 6G networks. Experimental validation confirms the feasibility and effectiveness of the proposed approach, making a significant contribution to the advancement of energy-efficient antenna technologies. I. INTRODUCTION The rapid evolution of 5G wireless communication systems has heightened the demand for reconfigurable antennas[1], [2], [3]. Traditionally, antenna reconfigurability has been achieved through the use of components such as PIN diodes[4], varactors[5], and photoconductive elements[6], which enable the tuning of frequency and radiation patterns. However, these solutions generally suffer from the drawback of requiring continuous static power for operation. Recently, non-volatile switches have emerged as a promising alternative for achieving reconfigurability in RF and microwave antennas, offering significant advantages in energy efficiency[7], [8], [9], [10]. For instance, non-volatile TiO2−x switches have been integrated into antenna arrays[11]. While these switches present an energy-efficient option, their relatively high on-resistance (~240 Ω) limits their performance in RF applications. Simultaneously, advancements in non-volatile RF switches using 2D materials such as MoS2 and hBN have shown potential[12], [13], [14], but their application in antenna systems remains underexplored. This paper introduces a novel strategy to address the limitations of traditional reconfigurable antennas by employing RF memristive switches in beamforming antenna arrays. Unlike conventional approaches that depend on static power, RF memristive switches provide reconfigurability without any static power consumption, enabling highly energy-efficient operation in wireless communication systems. The study details the design, simulation, and hardware implementation of a 2.4 GHz beamforming antenna array integrated with RF memristors, offering precise control of beamforming capabilities. This innovative approach not only enhances the energy efficiency of reconfigurable antennas but also addresses performance challenges associated with RF switches, such as power consumption and operational efficiency. By optimizing the antenna design, the proposed system expands the practical application of non-volatile switch technology, contributing to the advancement of next-generation wireless communication networks, including 5G and 6G. II. PROPOSED METHODOLOGY A. Phase shifter design Figure. 1. (a)The single structure of a 0°/180° coupler. (b) Combined three couplers with 4 zero static power switch, W1=1.20mm, W2=2.44mm, W3=2.20mm, L1=23.60mm, L2=14.10mm, and L3=9.97mm. W4=60.00mm, L4=70.40mm, and L5=6.00mm. The proposed model utilizes three 0°/180° couplers and four RF memristive switches to form the phase shifter for the phased array system can be seen in Fig. 1[15]. To illustrate the operation, a single coupler is analyzed first. When the excitation occurs at port 1, the output phase difference is 0°, meaning the signals are in phase. Conversely, with excitation at port 2, the output phase difference is 180°, producing out-of-phase signals. The addition of the RF memristive switches enables dynamic control over the output phase states. When combined with the three couplers, these switches enable precise control over the column outputs of the Hadamard matrix, corresponding to different beamforming states. In State A, the excitation occurs at port 1, with switches S1 and S4 in the off state and S2 and S3 in the on state. This configuration mirrors excitation at port 2 of both couplers in Group II, resulting in output phases of 0°, 180°, 180°, and 0° at ports 3 through 6, respectively. Here, 0° represents a '1' in the Hadamard matrix, while 180° corresponds to '-1'.In State B, the excitation occurs at port 2, with the same switch configuration. However, the inputs of the two couplers in Fig. 1(b) are inverted, producing outputs of 0°, 180°, 0°, and 180° at port 3 through © 2025. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to use any copyrighted component of this work in other works must be obtained from the IEEE. Link to publisher version with DOI: 10.1109/AP-S/CNC-USNC-URSI55537.2025.11266795 port 6. In State C, excitation returns to port 1, but switches S1 and S4 are now on, and S2 and S3 are off, causing both couplers in Group II to be excited at port 1, resulting in outputs of 0° across all ports. In State D, excitation occurs at port 2 with the same switch configuration as State C, but with inverted input values at the couplers, producing outputs of 0°, 0°, 180°, and 180° at the respective ports. This switching architecture demonstrates that by varying the excitation ports and the on/off states of the RF memristive switches, the antenna system can achieve different column outputs of the Hadamard matrix, enabling flexible and precise beamforming control. B. Antenna design Figure. 2. The structure of a single tapered slot antenna: (a) top view, (b) bottom view. W5=43.00mm, W6=21.00mm, W7=1.83mm, W8=2.75mm, W9=0.48mm, L6=56.00mm, L7=16.10mm, L8=8.25mm, L9=8.35mm, L10=5.04mm, L11=1.00mm, L12=21.50mm, W10=0.80mm, L13=2.40mm, L14=19.00mm, L15=11.64mm, R1=5.97mm, R2=0.35mm, R3=1.45mm and Φ=65°. Figure. 3. Reflection coefficient of a single tapered slot antenna. A 1×4 antenna array is designed and in order to achieve wider angle scanning, tapered slot antenna is used to implement the antenna array. According to the Fig. 3, the proposed antenna can operate at frequency 2.2GHz to 2.6GHz. C. Non-voaltile RF memristive switch (a) (b) Figure. 4.DC characteristics of the RF memristive switch: (a) applying a positive voltage, (b) applying a 10 ms negative voltage pulse of 8 V. Fig. 4 shows the capability of the RF memristive to switch between on and off states by adjusting the bias voltage. When the bias voltage is approximately 2V, the device transitions from a high resistance state (off state) to a low resistance state (on state). By applying an -8V voltage pulse with a duration of 10 milliseconds, the device returns from the low resistance state to the high resistance state, thereby reverting to the off state. During switching, a conductive filament forms between two electrodes by applying an electric field to the Nafion electrolyte, which can be seen in Fig. 5. A positive voltage at the Ag electrode and a negative voltage at the Au electrode move metal ions within the electrolyte, creating a conductive filament. This connection remains even after the voltage is removed, requiring no additional static power. When a reverse voltage is applied, the electric field causes the metal ions to migrate away, breaking the connection and restoring the system to its original state. The filament fabrication process can be seen in [16]. Figure. 5. Operation process of the non-volatile RF memristive switch. III. EXPERIMENTAL RESULTS AND DISCUSSION (a) (b) Figure. 6. Photographs of the fabricated phase shifter: (a) without switches, (b) with switches added (a) (b) Figure. 7. Photographs of the fabricated single tapered slot antenna: (a) top view, (b) bottom view. (a) (b) (c) (d) Figure. 8. Measured and simulated S-parameter magnitude and phase values of the phase shifter in four different states: (a) State A, (b) State B, (c) State C, and (d) State D. The comprehensive evaluation of the S-parameters and phase differences across four operational states of the phase shifter, as delineated in the accompanying figures, demonstrates a robust performance within the frequency spectrum of 2.36 GHz to 2.44 GHz. The analysis of Sparameters reveals uniform behaviour with subtle fluctuations, particularly noticeable in S11 and S22 as presented in Fig. 8 (a) and (b). Notably, these parameters illustrate a gradual increment in reflection loss with increasing frequency, indicative of a modest deterioration in impedance matching at elevated frequencies. A notable observation in Fig. 8 (a) is the fluctuation near 2.4 GHz, where an enhanced reflection coefficient in the S11 parameter suggests improved reflection attributes at this operational frequency. Stability characterizes the phase difference profiles throughout the observed frequency range. Nonetheless, the data reveal discrepancies between empirical measurements and simulation predictions, especially at distinct frequencies where significant deviations and instabilities manifest. For example, in Fig. 8 (d), the phase difference between ports 4 and 5 shows a marked decline, intensifying as the frequency nears 2.44 GHz. Despite these deviations from simulated projections, the congruence of the S-parameters and phase differences with the design specifications affirms the efficacy of the phase shifter. The device maintains consistent transmission properties and phase control across various states, thereby operating effectively within the stipulated frequency domain. These findings underscore the phase shifter's compliance with required performance standards, with minor discrepancies likely attributable to variances in manufacturing processes or the constraints of measurement techniques. Figure. 9. Measurement setup in an anechoic chamber. (a) (b) Figure. 10. (a)Measured reflected far-field pattern of zero static power reconfigurable antenna array (state C) (b)state D. The non-volatile reconfigurable antenna array was set up to implement far-field plane wave excitation, with a critical distance of over 2 meters maintained. This distance was calculated using the formula d = 2D2/ λ, where D is the maximum dimension of the antenna array. Comparative measurements with a metal sheet of identical size were conducted to establish a reference for the reflection amplitude and phase. These tests were carried out in an anechoic chamber, as illustrated in Fig. 9. The linearly polarized horn antennas (Aaronia AG, PowerLOG 70180), covering a frequency range of 700 MHz to 18 GHz, served as the receiver.These were connected to the N9918A vector network analyzer for the measurements. In Fig. 10, the test and simulation results of State C are almost the same, and we can clearly see the two peaks of the main side lobe. However, the main lobe of State D is obviously offset, about 8°. The reason for this is that each individual antenna of our test antenna array is fixed on a plastic foam board, and we can clearly see that the antenna on the plastic foam is not fixed very well, which may cause the arrangement of the antenna array to loosen when the turntable rotates, resulting in the spacing between its single antennas not being able to maintain half the wavelength. This will cause such a difference between the simulation and test results. If we need to improve the test methods in the future, the solution may be to design the antenna on the same PCB board as much as possible, so as to avoid such a situation. But in general, our research still achieved the process of simulation design and testing of simple non-volatile reconfigurable antenna array. TABLE I. COMPARISON OF RF MEMRISTIVE SWITCH AND DIODEBASED ANTENNA ARRAY ENERGY CONSUMPTION Ref. Number of Switches Static Power Supply (Assuming 50% Working) (W) Bias Voltage(V) Switch Type [17] 3 1.5 1.1 BAP64-03 [18] 64 16 0.45 BAR 50-02L E6327 [19] 12 3 0.2 DSG9500-000 [20] 8 2 0.89 SMP1345-079LF This work 4 0 2 RF Memristive Switch Table I compares the switching energy of the RF memristive switch in this work with the energy consumption of traditional diode-based antenna arrays, demonstrating the potential efficiency benefits of the proposed approach in RF applications. IV. CONCLUSION We successfully designed and implemented a beamforming antenna array with zero static power consumption using RF memristive switch technology. Through comprehensive simulations and physical production, the antenna system was able to achieve precise beam steering at multiple angles, demonstrating high efficiency and energy savings. The introduction of RF memristive switches not only eliminated static power consumption but also enhanced the system’s response speed and reliability, making it a significant improvement over traditional RF switch technology. This innovation holds great potential for energy-efficient applications in 5G/6G networks, IoT devices, and satellite communications. 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