A strictly causal numerical study of the pulsed operation of a weakly dispersive, leaky wave (LW) antenna is presented. The intricacies at the forefront of the electromagnetic (EM) field radiated from a gap-fed slot in a perfectly electrically conducting (PEC) sheet are evidenced for the first time. The radical effect of a free-space gap separating the PEC sheet from the dielectric half-space into which the slot radiates is demonstrated, thus providing time-domain (TD) arguments for the effectiveness of this essential element of leaky-lens antennas (LLAs). The response of the gapped structure to an excitation consisting of pulse trains is evaluated. The discussed results pave the way toward building a genuine TD counterpart of the LW radiation from gap-fed slots. Furthermore, they are conditional to understanding the transients occurring in between intervals when a steady-state, time-harmonic (TH) operation can be assumed, an extremely relevant ingredient to implementing highly complex modulations in carrier-based, wireless transfer.

A causality preserving interpretation of the electromagnetic (EM) leaky-wave (LW) propagation in space and time is proposed for the first time. The Cagniard-deHoop (CdH) joint transform technique is applied for elucidating the relation between time-domain (TD) head waves (HWs), body waves (BWs), Cherenkov wave effects, and LWs. It is conjectured that the LW phenomenon in the TD is associated with a local maximum in the observed signal that occurs between the arrivals of the HW and BW constituents. A quantitative analysis that enables the space-time localization of the LW effect is performed theoretically and, then, illustrated via representative examples including the pulsed EM radiation from both a line source above a dielectric half-space, and narrow-slot antennas.

The late-time evaluation of electromagnetic (EM) field quantities yielded by convolution integrals that combine Green's functions available at discrete time samples and strictly causal excitations is critically revisited. A typical situation is used for tracing the causes of the divergent late-time behavior that is often experienced. A framework combining a suitable integral partitioning with a polynomial approximation is shown to effectively guarantee the integrals' convergence. The formulation is validated via numerical experiments evidencing its accuracy and computational efficacy. The method is amenable to be used in a wide range of problems requiring the late-time evaluation of convolution integrals of the indicated type.

The amplitude-modulated, cosine powerexponential (PE) and windowed-power (WP) pulses are discussed, by insisting on their time-domain normalization. Illustrative examples of signatures and their correspondent frequency-domain behavior are given. These examples compellingly demonstrate the possibility to replace non-causal pulses of prevalent use by causal, or even time-windowed, pulses with closely resembling signatures.

An improvement of the wide-angular scan-loss compensation (SLC) and sidelobe level (SLL) in a small linear array with 23 elements is discussed. The array integrates small subarrays with an optimized pattern for SLC, while the SLL suppression is obtained by using a combination of elements with phase steering only and elements with amplitude/phase control in the center. This combination leads to a less number of T/R module. When the antenna is scanned to ±60°, a maximum first and peak SLL (FSLL and PSLL) of -15.1 dB are obtained. In addition, a -4.6 scan-loss is obtained, it means that the SLC is 2.4 dB with a Cavity-backed U-slotted Patch (CUP) antenna. These performance results are very attractive in particular for a small linear array with wide angular scanning capability.

The electric-line-source excited, pulsed electromagnetic (EM) field response on the surface of a highly contrasting thin sheet with dielectric and conductive properties is studied analytically in the time domain (TD) with the aid of the Cagniard-De Hoop technique. Closed-form TD expressions reveal anomalous highly oscillatory EM transients propagated over the surface of the layer. Illustrative numerical examples demonstrate the EM surface phenomenon.

The pulsed electromagnetic (EM) field transfer between a horizontal electric dipole (HED) and a transmission line is described analytically with the aid of the time-domain (TD) reciprocity theorem and the Cagniard-de Hoop technique. A suitably chosen wave-slowness representation makes it possible to cast the pertaining interaction integrals into a form amenable to analytical solution. The closed-form coupling model thus obtained clearly reveals the dependence of configurational parameters on the wireless signal transfer. Numerical results are presented and validated using a 3-D EM computational tool.

An advanced design, adding a significant first sidelobes level (FSLL) improvement to a previously introduced wide-angular-scanning, linear array prototype with demonstrated scan-loss compensation (SLC) and sidelobes suppression features is discussed. The linear array makes use of in-line subarrays for SLC and an additional amplitude taper in its central, uniform region for lowering the FSLL with as much as 4\mathrm{d}\mathrm{B} at \pm 60 {\mathrm{o}} scanning (13\mathrm{d}\mathrm{B} at \pm 20 {\mathrm{o}} scanning). Several Taylor-type amplitudes tapers are compared, the best overall performance improvement being observed for a -18dB prototype taper. The advocated solution is highly suitable to high-sensitivity radars requiring a fast-scanning, fan-beam.

This article explores some dominant trends in teaching classical electromagnetic (EM) field theory in electrical engineering (EE) undergraduate curricula. The acronym EM will be used interchangeably to designate either electromagnetic or electromagnetism. The intended significance will be evident from the context.

A novel pulsed photoconductive THz source is presented that is able to radiate mW-level average powers, over a large bandwidth by exploiting both the optical and electrical properties of photoconductive sources and the ultrawideband properties of connected antenna arrays. An optical system composed of a micro-lenses array splits the laser beam into N × N spots that host the active excitation of the antenna arrays. An 'ad hoc' network has been adopted to bias the array active spots in order to implement a connected antenna array configuration. The array feeds a silicon lens to increase the directivity of the radiated THz beam. A slot array prototype has been designed, fabricated, and measured. The proposed solutions achieve excellent power radiation levels by making use of an accurate electromagnetic design. This solution can offer enhancements to any active system relying on pulsed photoconductive antennas.