使用局部角度-时间扩展函数法恢复Rotman透镜近场图像

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"局部角度-时间扩展函数法修复Rotman透镜近场图像" 本文主要讨论了在微波/毫米波成像领域中，Rotman透镜的应用及其在近场成像时遇到的问题与解决方案。Rotman透镜作为一种期望设备，因其能够实现平行多光束成像而在实时成像系统中具有重要价值。然而，在近场成像场景下，由于来自目标的散射波并非平面波，导致透镜的光束端口扩大，进而产生模糊的近场图像，影响成像质量。针对这一问题，作者提出了基于局部角度-时间扩展函数（ATSF）的滤波方法来减少离焦模糊。这种方法旨在简化Rotman透镜的去模糊过程，以提升近场图像的分辨率和质量。通过模拟和实验验证，结果显示，利用该方法能够在角度和径向方向上显著提高近场图像的清晰度。论文引用了多个关于微波光学技术与功率分路器设计的研究，如[10-14]，这些研究涉及新型功率分路器的设计，具有连续功率分割、可调功率比、简单布局、宽频带和可调功率分配比例等特点。这些技术虽然不是本文的核心，但它们展示了微波领域内的创新设计，可能为解决Rotman透镜成像问题提供了相关的技术支持或灵感。 "局部角度-时间扩展函数法修复Rotman透镜近场图像"这篇论文关注的是如何利用先进的滤波技术改进近场成像系统的性能。通过提出ATSF方法，可以有效地处理Rotman透镜因非平面波散射导致的成像模糊，从而提高近场成像的清晰度和分辨率，对于微波/毫米波成像技术的进步具有重要意义。

IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 63, NO. 5, MAY 2015 2353

[10] S. Bulja and A. Grebennikov, “A novel variable power divider with

continuous power division,” Microw. Opt. Technol. Lett., vol. 55, no. 7,

pp. 1684–1686, Jul. 2013.

[11] W. Sahyoun, A. Jrad, J. M. Duchamp, A. El-Helwani, and P. Ferrari, “A

compact three port power divider with tunable power ratio,” Microw. Opt.

Technol. Lett., vol. 55, no. 2, pp. 357–363, Feb. 2013.

[12] K. K. M. Cheng and P. W. Li, “A novel power-divider design with unequal

power-dividing ratio and simple layout,” IEEE Trans. Microw. Theory

Tech., vol. 57, no. 6, pp. 1589–1594, Jun. 2009.

[13] K. K. M. Cheng and M. C. J. Chik, “A frequency-compensated rat-

race coupler with wide bandwidth and tunable power dividing ratio,”

IEEE Trans. Microw. Theory Tech., vol. 61, no. 8, pp. 2841–2847, Aug.

2013.

[14] T. Y. Han, C. J. Shih, and J. S. Row, “Polarization reconﬁgurable

microstrip patch antenna,” Microw. Opt. Technol. Lett., vol. 55, no. 3,

pp. 471–474, Mar. 2013.

Near-Field Image Restoration for Rotman Lens

by Localized Angle-Time Spread Function-Based

Filtering Method

Min Yu, Deshuang Zhao, Yuanwei Jin, and Bing-Zhong Wang

Abstract—Rotman lens is a prospective device for real-time

microwave/millimeter-wave imaging by virtue of its parallel multi-

beam functionality. For imaging purposes, a Rotman lens intrinsically

requires that the scattered waves arriving at the array be plane waves.

However, this requirement cannot be met in near-ﬁeld imaging appli-

cations, as the scattered waves from targets in the near ﬁeld defocus at

the beam ports of the lens because of the nonplane wave scattering. As

a result, out-of-focus blurs appear in the near-ﬁeld images, thus leading

to degradation of picture quality. To address this problem, we propose

a localized angle-time spread function (ATSF)-based ﬁltering method to

reduce out-of-focus blurs. With the proposed method, the deblurring pro-

cess becomes simple for a Rotman lens. Both simulations and experiments

were performed. The results show that the proposed method signiﬁcantly

improves the quality of near-ﬁeld images with enhanced resolutions in

both angular and radial directions.

Index Terms—Image restoration, near-ﬁeld imaging, out-of-focus blur,

Rotman lens.

I. INTRODUCTION

Rotman lens is generally r egarded as a low-cost beam-forming net-

work for designing parallel multibeam arrays [1]–[3], retro-directive

arrays [4], and spatial Fourier transform devices [5]. Due to the parallel

Manuscript received December 08, 2013; revised February 02, 2015;

accepted February 16, 2015. Date of publication February 27, 2015; date of cur-

rent version May 01, 2015. This work was supported by the National Natural

Science Foundation of China under Grant 61371106, Grant 61331007, and

Grant 61201089). The work of Y. Jin was supported in part by the U.S. National

Science Foundation under Grant CMMI-1126008 and in part by the Army

Research Ofﬁce under Grant W911NF-11-1-0160. (Corresponding author:

D. Zhao.)

M. Yu, D. Zhao, and B-Z. Wang are with the School of Physical Electronics,

University of Electronic Science and Technology of China, Chengdu 610054,

China (e-mail: dszhao@uestc.edu.cn).

Y. Jin is with the Department of Engineering and Aviation Sciences,

University of Maryland Eastern Shore, Princess Anne, MD 21853, USA.

Color versions of one or more of the ﬁgures in this communication are

available online at http://ieeexplore.ieee.org.

Digital Object Identiﬁer 10.1109/TAP.2015.2408362

multibeam formation functionality, researchers have recently found

that Rotman lens is a promising candidate for real-time microwave

or millimeter-wave imaging applications [6]. Real-time imaging has

important applications in many ﬁelds. However, these lens systems are

typically limited to far-ﬁeld imaging, because their parallel multibeam

formation is based on the condition that the scattered waves arriving at

the array are plane waves. In the near ﬁeld, the nonplane waves scat-

tered from a near-ﬁeld target will spread across several beam ports of

the Rotman lens. As a result, out-of-focus blurs appear in the near-ﬁeld

images.

In optical imaging systems, out-of-focus blurring is a common

problem. For image deblurring, ﬁltering is usually employed to restore

the images by utilizing point spread function (PSF) to model the out-

of-focus signals [7], [8]. PSF is deﬁned as the spatial response of an

imaging system to a point source. This function can characterize the

out-of-focus blurring of ideal point objects. However, when it comes

to modeling the blurs in the near-ﬁeld images by a Rotman lens using

PSFs, two important factors must be considered: the blurs are time-

angle-dependent and the blurs vary along the radial distance. These

two factors are quite different from the blurring effects that occur in

optical imaging systems, thus posing challenges to Rotman lens.

Furthermore, the performance of a real-time imaging system is

often limited by computational time. Most of the existing algorithms,

such as back-propagation [9], [10], virtual-echo projection [11], and

propagation back-propagation [12], can be applied to near-ﬁeld imag-

ing problems in principle. However, the high computation cost of

calculating the Green’s functions for these algorithms make the sys-

tems unsuitable for the real-time applications [13], [14]. Here, we

attempt to facilitate the Rotman lens with simultaneous real-time near-

ﬁeld and far-ﬁeld imaging capability. Therefore, fast algorithms are

desired for the imaging systems.

In this communication, a fast ﬁltering method is developed for that

purpose. This method is based on a Weiner ﬁltering approach devel-

oped by the localized angle-time spread functions (ATSFs). Although

other ﬁlters such as the direct inverse ﬁlter, the geometric mean ﬁlter,

and the constrained least-square ﬁlter can be utilized, our preliminary

results show that the direct inverse ﬁlter works poorly as the noise

levels increase. The other two ﬁlters have a better performance than

the direct inverse ﬁlter, but their design procedure is more complex.

Due to space limitation, we present only the results by the Weiner

ﬁltering methods. To verify our method, we conduct both simula-

tions and experiments using a fabricated microstrip Rotman lens and

demonstrate its superior performance in image deblurring.

II. F

AR-FIELD IMAGING PRINCIPLE OF ROTM A N LENS

Fig. 1 shows the photograph of a fabricated microstrip Rotman lens

used for this study. The lens is fabricated on a 1.5-mm-thick FR4

substrate with a size of 300 mm × 320 mm. The relative dielectric con-

stant of the substrate is 4.5. The frequency range is from 3 to 8 GHz.

The lens consists of a lens cavity, 14 antenna ports, 11 beam ports,

and 4 dummy ports. The lens cavity is used to focus the incident

waves on the beam ports. The antenna ports (A1–A14) are for physical

connection to a 273-mm aperture array with a uniform inter-element

spacing of 21 mm. The beam ports (B1–B11) are for receiving the sig-

nals from the lens cavity. The dummy ports (D1–D4) are terminated

with loads for absorbing inter-cavity reﬂections. The delay lines are

designed to compensate for the phases of the incoming waves from

different angles. A comprehensive description of Rotman lens design

can be found in [15] and [16].

See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.

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