A Channel Phase Self-compensation Method for Active-Integrated Arrays

SUN Liying; LU Yunlong; XU Jun; HU Yang

doi:10.11999/JEIT251325

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SUN Liying, LU Yunlong, XU Jun, HU Yang. A Channel Phase Self-compensation Method for Active-Integrated Arrays[J]. Journal of Electronics & Information Technology. doi: 10.11999/JEIT251325

Citation:

SUN Liying, LU Yunlong, XU Jun, HU Yang. A Channel Phase Self-compensation Method for Active-Integrated Arrays[J]. Journal of Electronics & Information Technology. doi: 10.11999/JEIT251325

SUN Liying, LU Yunlong, XU Jun, HU Yang. A Channel Phase Self-compensation Method for Active-Integrated Arrays[J]. Journal of Electronics & Information Technology. doi: 10.11999/JEIT251325

Citation:

SUN Liying, LU Yunlong, XU Jun, HU Yang. A Channel Phase Self-compensation Method for Active-Integrated Arrays[J]. Journal of Electronics & Information Technology. doi: 10.11999/JEIT251325

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A Channel Phase Self-compensation Method for Active-Integrated Arrays

doi: 10.11999/JEIT251325 cstr: 32379.14.JEIT251325

SUN Liying¹,
LU Yunlong^{1
,
,},
XU Jun²,
HU Yang¹

1.
Faculty of Information Science and Engineering, Ningbo University, Ningbo 315211, China
2.
State Key Laboratory of Millimeter Waves, School of Information Science and Engineering, Southeast University, Nanjing 210096, China

Funds: The National Natural Science Foundation of China (62571285, 62171242), Zhejiang Provincial Natural Science Foundation (LR24F010001), Ningbo Natural Science Foundation (2024J027), Ningbo Municipal Science and Technology Innovation Yongjiang 2035 Key R&D Plan (2025Z206)

Received Date: 2025-12-15
Accepted Date: 2026-02-05
Rev Recd Date: 2026-01-30

Available Online: 2026-02-28

Abstract

Abstract

The seamless integration of active circuitry and antennas can effectively improve link performance and system integration. At present, active-integrated antennas are mainly designed by adjusting the antenna impedance while maintaining the desired radiation characteristics to achieve direct matching with active transistors. However, the effect of the antenna’s complex impedance on the phase response of the active channel, as well as its potential application in active-integrated phased arrays, has not been thoroughly studied. This paper proposes a channel phase self-compensation method for active-integrated arrays. For each active channel, the active transistor is directly integrated with the radiating element, where the load impedance at the transistor drain is matched to the input impedance of the antenna element. Under a constant active gain, the required complex load impedance is solved to establish an explicit mapping between the phase response of each active channel and its corresponding load impedance. According to the phase-shift requirements among array channels, appropriate load impedances are selected as the input impedances of the corresponding radiating elements. This approach applies a predefined phase distribution to each channel without using external phase-shifting structures. It can control the initial beam direction or compensate for the path difference between elements in conformal arrays. An active-integrated phased-array antenna with a preset beam direction is designed as a demonstration example to verify the effectiveness of the proposed method. The method provides an efficient design approach for next-generation active-integrated arrays. Objective In the traditional design approach, active circuit channels and antenna arrays are matched to 50 Ω before interconnection. This configuration occupies considerable physical space and limits system-level integration. In addition, insertion loss in passive matching networks and mismatch loss at the interconnections reduce overall link performance. Direct co-integration of active circuitry and antenna elements can address these limitations. However, multi-channel active-integrated antenna arrays often require one or multiple superimposed phase distributions across the channels to satisfy different application requirements, such as initial beam offset in fuze systems, wavefront compensation in conformal active phased arrays, and wide-angle beam scanning. These phase gradients are typically realized through backend phase-shifting networks. In this work, the complex impedance characteristics of the antenna are adjusted when it is directly integrated with the active circuitry. The phase response of the active-integrated channels can therefore be tuned within a certain range without using complex matching networks or additional phase shifters. This strategy reduces the complexity and performance requirements of the backend phase-shifting network. The advantages are more evident in millimeter-wave, high-frequency, and terahertz systems, where the available phase-shift range of phase shifters is limited. Methods Phase self-compensation of the active channels is achieved through the direct integration of the active transistor and the radiating element. In this configuration, the drain output of the transistor is directly connected to the input of the radiating element, and impedance transformation is realized within the antenna element. The proposed method includes three main steps. (1) The active transistor is first modeled as a two-port network. By evaluating the antenna element’s complex impedance as the load on different constant-gain circles, the mapping between the phase response of the active channel and the load impedance is established. The achievable phase-shift range of the active channel is then determined. (2) According to the required phase-shift distribution among the array channels, suitable combinations of active gain and corresponding complex load impedances (not unique) are selected. These combinations are not unique. (3) The realizability of the selected impedances is examined according to the characteristics of the radiating element. The impedance values with the highest feasibility are implemented by optimizing the radiating element, which includes fine adjustment of its geometry and feed position to meet the target impedance. When the radiating element is modified, particularly for circularly polarized elements, desirable radiation characteristics must also be preserved, including good axial ratio and beam-scanning performance. Results and Discussions The proposed phase self-compensation mechanism enables the array to achieve initial beam pointing and compensate for path-length differences caused by special array geometries, such as conformal or curved surfaces, without using additional phase-shifting structures. Therefore, the performance requirements of the backend phase-shifting network in active phased arrays can be reduced. To verify the effectiveness of the proposed method, a 1×4 circularly polarized active-integrated linear array (Fig. 9) is designed and demonstrated. Based on channel-level impedance calculations (Fig. 6) and an analysis of the antenna-element impedance characteristics (Fig. 8), a phase gradient of 38° between adjacent channels is synthesized and applied to the circularly polarized active-integrated array. Without degrading the circular polarization performance and without external phase-shifting circuitry, the initial beam direction of the active-integrated phased array is shifted to the desired angle of θ₀ = 12° (Fig. 13). The phase self-compensation design does not degrade the beam-scanning capability of the array. After an additional phase gradient is applied for beam steering, the array achieves a scanning range of up to 50°. The gain reduction remains within 2 dB relative to the initial pointing direction, and the axial ratio remains below 4 dB throughout the scanning range. Conclusions Within the framework of active-integrated arrays, this work uses the phase-tuning effect produced by the complex impedance at the antenna port when the radiating element is directly matched to the active transistor. A desired phase-gradient distribution can therefore be synthesized among the channels of an active-integrated phased array within an achievable range. This capability enables compensation for required phase distributions, such as preset beam direction and path-length equalization in conformal-array applications, without relying on additional phase shifters. Therefore, the complexity and performance requirements of the backend phase-shifting circuitry are reduced. The effectiveness of the proposed method is validated through a multi-channel circularly polarized active-integrated phased-array prototype with a preset beam direction. Both full-wave simulations and experimental measurements confirm that the phase self-compensation mechanism provides the required initial beam pointing while preserving beam-scanning capability and polarization performance. This study provides a new approach for the design of high-efficiency next-generation active-integrated phased arrays.
- Active integration,
- Phased array,
- Phase compensation,
- Beam scanning,
- Circular polarization

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References(20)

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