| Abstract: | An approach to enhance antenna spectral efficiency is proposed based on combining spacetime electromagnetic (EM) models of Tx/Rx antennas with orthogonal frequency division multiaccess (OFDM), leading to the EM‐OFDM, a technology capable of removing intersymbol interference (ISI) in high‐data rate communication links caused by the EM‐induced distortion antenna effects. The proposed approach differs from traditional OFDM in wireless communication in several aspects. First, the technique suggests a new decoupling approach by treating each given antenna transreceive device pair as a “stand‐alone channel” with its own distortion mechanisms considered separately from the propagation channel. Moreover, the deterministic distortion caused by the nonflat pure antenna EM filtration effects is exploited to carefully design a specialized OFDM transmission techniques based on the antenna parameters, not the multipath fading channels often invoked in conventional uses of OFDM methods. (The EM‐OFDM, however, can be combined with a traditional OFDM later if fading channels are present.) In this manner, a more efficient implementation of the wireless link equalization strategy may be enacted since the EM antenna origin of ISI is very different from the traditional propagation channel one. As a proof of concept, the proposed EM‐OFDM method is implemented for a single‐input‐single‐output link comprised of half‐wavelength linear wire antennas. A careful use of finite difference time‐domain to provide EM data allowed the construction of 64 decoupled “pure antenna OFDM subchannels.” Simulation results suggests that the antenna‐based OFDM system is capable of completely neutralizing all ISI effects caused by the limited antenna matching bandwidth of the transreceive wires, therefore, supporting considerably higher data rates with low symbol error rate (SER). A concrete evaluation of the SER using quadrature phase‐shift keying (QPSK) digital carrier modulation resulted in an increase of the effective antenna digital communication spectral efficiency by ratios up to 300%. Moreover, the EM‐OFDM error rate was found to be close to the ideal QPSK level or the maximum possible theoretical limit. Thus, combining detailed EM knowledge with standard signal processing methods can lead to considerable improvement in system design without modifying the antenna physical layout. The proposed approach is expected to play a role in the forthcoming 5G/6G and millimetre wave technology systems currently under development where there is a trend toward integration of EM and digital signal processing at the physical layer level. |
