The Numerical Electromagnetics Code (NEC) - a brief history

Abstract

IntroductionThe Numerical Electromagnetics Code, NEC as it is commonly known, continues to be one of the more widely used antenna modeling codes in existence. With several versions in use that reflect different levels of capability and availability, there are now 450 copies of NEC4 and 250 copies of NEC3 that have been distributed by Lawrence Livermore National Laboratory to a limited class of qualified recipients, and several hundred copies of NEC2 that had a recorded distribution by LLNL. These numbers do not account for numerous copies (perhaps 1000s) that were acquired through other means capitalizing on the open source code, the absence of distribution controls prior to NEC3 and the availability of versions on the Internet. In this paper we briefly review the history of the code that is concisely displayed in Figure 1. We will show how it capitalized on the research of prominent contributors in the early days of computational electromagnetics, how a combination of events led to the tri-service-supported code development program that ultimately led to NEC and how it evolved to the present day product. The authors apologize that space limitations do not allow us to provide a list of references or to acknowledge the numerous contributors to the code both of which can be found in the code documents.

Interaction between the RF Field of MRI Apparatus and Pacemakers

“…These studies have been performed by using numerical technique for the solution of the EM and thermal problem, respectively. Among the EM solvers those based on the finite difference time domain (FDTD) technique are the most popular (Taflove & Hagness, 2000) but also the method of moments (MoM) has been largely used (Burke & Poggio, 1981). For the solution of the thermal problem the Bio-heat equation (Pennes, 1948) has been solved by means of explicit or implicit (ADI) solutions (Bernardi et al, 2003;Pisa et al, 2003).…”

Modified Two-Element Yagi-Uda Antenna With Tunable Beams

“…The calculated results by using (8), along with the simulated results by using the method of moments-based numerical electromagnetic code (NEC) [21], are shown in Fig. 3.…”

An electrically small planar antenna

“…The antenna simulations, which used the Numerical Electromagnetics Code (NEC-4) [4], were initially done for values of length, l and height, h fixed at 5 cm. The value of h 1 was varied from .4 cm to 1.2 cm, h 2 from 1 cm to 3 cm, w from .5 cm to 2.0 cm, L from .1 to 1.0 µHenries and α had values of 30º, 45º and 60º.…”