Relevance of electromagnetics in wireless systems design

Current research on wireless radio frequency (RF) systems often makes unphysical simplifying assumptions and treats the associated signal processing and electromagnetic (EM) analyses independently, resulting in improper inclusion of the underlying physics (EM theory) of such systems and consequently leading to inaccurate and erroneous performance predictions. To achieve accurate modeling and predictions, EM theory and signal processing must be intelligently merged. Examples of such errors commonly appearing in both fields are the following: not including the platform on which an antenna is mounted, which leads to completely erroneous predictions of antenna coverage [1], a serious issue for designing relevant antennas for RF systems, and optimizing transmitted waveforms without including proper differentiability requirements imposed by Maxwellian electromagnetics yielding inaccurate and physically unrealizable waveforms [2]. Because discussions of these topics appear in [1] and [2], this article concentrates on the different concepts of channel capacity and their implications and on the antenna and its relationship to the maximum power transfer theorem. Although the discussion addresses communication systems, much of it is applicable to noncommunication systems. A future of improved performance and better spectral harmony requires coding at RF, initially envisioned by Shannon and subsequently investigated by Viterbi, which is similar to the coding in global positioning satellite (GPS) and satellite communication. Such a methodology can also be carried out in radar in which, for example, a radar can transmit coded waveforms, such as a Barker code, to increase detection capabilities.