Lorentz Reciprocity Theorem


Author(s):  
Xiao Hu ◽  
Yang Qiu ◽  
Qing-Lin Xu ◽  
Jin Tian

This paper presents an efficient hybrid method consisting of Lorentz reciprocity theorem, finite-difference-time-domain (FDTD) method, thin wire model, transmission line (TL) equations and transfer impedance model, which can be utilized to analyze the system-level transient responses of the microstrip antenna system with antenna, metallic enclosures, braided shielded cable, and lumped element, when illuminated by an external electromagnetic pulse (EMP). In order to avoid over-fine mesh generation and repeated modeling of the antenna in multiple simulations, Lorentz reciprocity theorem is employed to extract an equivalent source model of antenna coupling, thereby improving the computational efficiency. Then, the transfer impedance model and thin wire model are incorporated into the FDTD-TL method efficiently to deal with the back-door coupling through the shielding layer of feeding coaxial cable. Finally, the hybrid FDTD method combined with the extracted equivalent source of antenna coupling is utilized to solve the coupling responses of the whole antenna system. The results of numerical simulation are verified by comparing with the simulation results of CST CS. Then, considering the influence of different incident conditions of external EMP, the characteristics of the coupling response of the system are analyzed. The obtained coupling response information demonstrate that the proposed method is available for further designing electromagnetic protection of the inner circuits of the microstrip antenna system against the impact of external EMP.



2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Nelson Jorge G. Fonseca

The Lorentz reciprocity theorem enables us to establish that the transmitting and receiving patterns of any antenna are identical, provided some hypotheses on this antenna and the surrounding medium are satisfied. But reciprocity does not mean that the antenna behaves the same in the transmitting and the receiving modes. In this paper, array antennas fed by multiple beam forming networks are discussed, highlighting the possibility to have different values of internal losses in the beam forming network depending on the operation mode. In particular, a mathematical condition is derived for the specific case of a multiple beam forming network with lossless transmitting mode and lossy receiving mode, such a behavior being fully consistent with the reciprocity theorem. A theoretical discussion is provided, starting from a simple 2-element array to a generalM×Nmultiple beam forming network. A more practical example is then given, discussing a specific4×8Nolen matrix design and comparing theoretical aspects with simulation results.



1959 ◽  
Vol 37 (2) ◽  
pp. 144-159 ◽  
Author(s):  
R. F. Millar

A solution is obtained to the problem of radiation from a slot in a parallel-plate transmission line when excited by an E-polarized, dominant mode wave. Expressions are obtained for the reflection and transmission coefficients, and the polar diagram of the radiated field. Explicit calculations are performed when the width of the slot is much greater than the free-space wavelength of the incident radiation.An application of the Lorentz reciprocity theorem yields, without further analysis, the amplitude and phase of the propagated wave which is excited in the line by an incident cylindrical or plane wave.





Sign in / Sign up

Export Citation Format

Share Document