Elsevier

Optik

Volume 121, Issue 11, June 2010, Pages 1003-1008
Optik

Dual-mode MMW/IR simulation of beam combiner

https://doi.org/10.1016/j.ijleo.2008.12.013Get rights and content

Abstract

Along with the development of the optoelectronic interference technology, invisible technology and anti-radiation missile technology, missile guidance with single band or single mode cannot adapt for modern warfare. So the technology of combined guidance is proposed. In the field of combined guidance, MMW/IR combined guidance is more significant. The critical component of the MMW/IR semi-physical simulation will be discussed in this paper, and the selection principle of the substrate and coating materials used for dichroic beam combiner (DBC) is analyzed: MMW/IR beam combiner. By researching the method of the beam combiner of 8–18 GHz MW and 3–5 μm IR, the theory and simulation are discussed in detail in this paper. And the result is given. At the same time, the distortion effect on the MMW signal is analyzed theoretically and the method is presented. Substrate material is selected. The main problems and study factors include: MMW transmission, insertion phase delay, size of substrate material, and coating. At last, the substrate material is determined, and the thickness of the substrate material is optimized.

Introduction

With the development of the technique of electrooptical jamming and photoelectronic reconnaissance, the modern warfare environment of missile becomes more and more complicated and wicked. The single-mode homing seeker cannot accomplish the mission of target detecting and tracking, so the dual-mode or multi-mode compound seeker is becoming more and more necessary.

IR/MMW dual-mode compound guidance technology is considered the most promising guidance technology. It combines the IR and the MMW guidance system in a complementary way, which overcomes each weakness and combines advantages of both. The advance of IR/MMW dual-mode compound guidance technology, particularly the advance of IR/MMW dual-mode common-aperture seeker had led to a requirement to develop the simulation tools. The most important techniques for supporting systems development are the hardware-in-the-loop simulation [1], [2], [3]. Compared to single-mode simulation facilities, dual-mode simulation facilities must be able to present simultaneous MMW and IR scene. So it is considered to be the most challenging problem. Currently, dual-mode simulation technology is being researched and developed in the USA and Europe, and a great progress has been made. Research on the dual-mode simulation technology in China is just in the initial stage, and some key technologies still need to be broken through.

In this paper, the dual-mode simulation is researched. The goal is to offer a high-powered simulation method for compound guidance technology. Based on the requirement of dual-mode simulation, two key technologies of dual-mode simulation including dichroic beam combiner (DBC) and IR scene projection system were analyzed and designed.

The main content includes: MMW transmission, insertion phase delay (IPD), size of substrate material, and coating. At last, the substrate material was determined, and the thickness of the substrate material was optimized.

Section snippets

Principle of IR/MMW combiner

The role of IR/MMW combiner is to synthesize the beam of infrared and millimeter waves to compound wave. The basic starting point is to find a substrate, which can transmit through the microwave and reflect the infrared film [4]. Polishing and anti-plating with one- or multi-layer film on the substrate can reflect the infrared light. Choose a suitable point on the incident and the substrate size; the two incident waves of microwave and infrared waves combine to form a compound wave through the

IPD of host material

IPD is a retarding phase which is relative to remove the flat front-to-back variation of transmission wave phaseIPD=φs-2πλ0dcosθ=θ-θ3+θ2-2πλ0dcosθwhereφs=φ-φ3+φ2φ=2πλ0dεr-sin2θφ3=arctanr02sin2ψ1-r02cos2ψφ2=arctanA2r02sin(2φ+2ψ)1-A2r02cos(2φ+2ψ)

To low-loss dielectric [5], [6], φ3=arctan(r02sin2ψ/(1-r02cos2ψ))=0,IPD=φs-2πλ0dcosθ=2πλ0d(εr-sin2θ-cosθ)+φ2

Here,φ2=arctanA2r02sin2φ1-A2r02cos2φ

The relationship between IPD, dielectric constant, and loss tangent

Fig. 1 shows the three-dimensional solid relation of IPD, εr and tan δ at two polarized states, in which the incident angle is 22.5° and the thickness of dielectric flat is 20 mm.

Fig. 2 shows the three-dimensional solid relation of IPD, εr and tan δ at horizontal polarized state, in which the incident angle is 22.5° and the thickness of dielectric flat is 20 mm.

From Fig. 1, Fig. 2 we can get:

  • (1)

    IPD is greater with the increase of εr. To the change of tan δ, IPD has minute influence.

  • (2)

    MMW polarized state

The relationship between IPD, thickness, and incident angle

Fig. 3 shows the relationship between IPD, thickness of host material and incident angle when εr=4, tan δ=0.001. From Fig. 4 we can get:

  • (1)

    IPD increases with the increase of the thickness of the material, which is almost in direct proportion. IPD increased gradually with the increase of incident angle, especially smaller incident angle, slower speed increase.

  • (2)

    Polarized state of MMW has little influence on IPD. IPD is almost equal for the two polarized waves.

The relationship between IPD and frequency

Fig. 4 shows the change of IPD relative to incident angle in the frequency of 93, 94, and 95 GHz when εr=4, tan δ=0.001 and the thickness of host material is 20 mm. From Fig. 4 we can see that IPD increases with the increase of frequency.

In the dual-mode simulation of IR/MMW, using quartz glass as a beam combiner host material is realistic.

Thickness optimization of quartz host material

Under the premise of specified fusing quartz glass as the host material, using the transmission function |T|2, we optimize the thickness of the host material. Here, the dielectric constant of quartz glass to MMW is εr=3.33, loss tangent is tan δ=0.001.

If the material is determined, transmission is mainly related to the thickness of host material, incident angle of MMW and frequency of MMW.

When the incident angle is less than 30°, transmission of MMW signal is almost equal at two polarized

Summary

  • (1)

    The distortion of MMW signal by beam combiner is analyzed. The analysis and calculation method is given.

  • (2)

    Selection rules of combiner host material are researched. The relationship between the MMW transmission, IPD and host material electricity parameter, thickness of material and incident angle of MMW is studied with numerical simulation method.

  • (3)

    The feasibility of quartz glass as the host material of beam combiner is confirmed. With quartz glass, the thickness of the material is optimized. The

Acknowledgments

The financial support for this study was provided by Natural Science Foundation of Yunnan Province, China (Grant no. 2008F041M). The authors would like to thank the teacher Baojun Zuo for his suggestions and selfless help.

References (6)

  • M. Bender, D.B. Beasley, Design of a large pupil relief broadband collimator for use in a MMW/IR HWIL facility [A],...
  • L. Sadovnik, A. Manasson, V. Manasson, V. Yepishin, Infrared/millimeter wave beam combiner utilizing holographic...
  • J. Delaballe et al.

    Local complex permittivity measurement of MIC substrates, AEU

    Electron. Commun.

    (1981)
There are more references available in the full text version of this article.

Cited by (0)

View full text