The simple planar shape and wideband input impedance of the bow‐tie antenna make it suitable to diverse wideband applications. However, the radiation pattern of this kind of antenna is not stable and the gain in the broadside direction deteriorates with increasing frequencies. In this article, the operation of both the triangular and the rounded‐edge versions of the bow‐tie antenna is thoroughly investigated and the performance thereof is compared. A technique to maximise such performance, which consists of inserting radially aligned grooves in the radiators' ends, is presented. The bandwidth, defined by a broadside gain of at least 2 dBi and a reflection coefficient magnitude of less than −10 dB, is improved from 85.7% to 97.9% in simulations. Such an improvement is validated through the measurement of two prototypes, in which the presented technique also increases the broadside gain in up to 1.5 dB, with no significant change in the shapes of the radiation patterns and in the reflection coefficient magnitude.

When a wideband antenna is backed by an artificial magnetic conductor (AMC) reflector, the bandwidth is reduced. With the optimization of the shape of the AMC it is possible to exhibit multiband behavior, but the problem becomes complex if the bands are also intended to be wide. In this study, a methodology that exploits both the expected in-band and out-of-band behaviors of a dual-band AMC was used to design a low-profile, triple-band, and wideband directive antenna. The methodology was validated with a prototype suitable for the European standards of 4G/5G and Wi-Fi 2.4/5/6E, operating within the following bands: 2.4–2.7 GHz, 3.4–3.8 GHz, and 5.17–6.45 GHz. The measured results showed respective peak values of 8.0, 9.1, and 10.5 dBi for the broadside realized gain, front-to-back ratios larger than 19 dB, cross-polarized levels lower than -18 dB, and stable half-power beamwidths within each band. Furthermore, 3 dB gain bandwidths of 34.4%, 19.7%, and 31.0% were also measured.

The latest works on the radar pulse de‐interleaving in electronic support measures (ESM) systems have not completely solved the missing pulses problem yet. The authors present a pulse detection algorithm that aims at, if not eliminating it, diminishing the rate of pulses not detected because of the fact of being superimposed in other ones. Experiments set up on an ESM system based on software‐defined radio (SDR) showed that the algorithm detection rate was near a hundred per cent and the false alarm rate was near zero when pulse amplitudes were >3.9 mV in the SDR input. This work is suggested for the areas of digital and radar signal processing and electronic warfare.

Blinking jamming is an active self-screening technique performed by at least two aircraft to tackle monopulse radars and all complexity related thereto. Nowadays, the technique can be performed with digital radiofrequency memories (DRFMs), which are cumbersome, complex, expensive, need a dedicated compartment and antenna, and introduce spurs in the signals. In this paper, we propose an alternative to the implementation of blinking jamming with DRFMs, namely with reconfigurable metasurfaces. By covering the aircraft parts that most contribute to the radar cross-section (RCS), reconfigurable metasurfaces can interchangeably absorb or amplify impinging waves, making the aircraft ‘blink’ from the radar perspective. To validate the feasibility, simulations accounting for realistic phenomena are conducted. It is seen that, if the aircraft RCS can be varied in a ratio of 10:1, either with absorptive or power-amplifying metasurfaces, a performance similar to that of the DRFM is achieved. Furthermore, a ratio of 2:1 is sufficient to make the radar antenna system movements exceed the angular range of the formation. We also anticipate our work to be a starting point for completely new ways of countering radars, e.g., with countless small drones performing passive or active stand-off blinking jamming.

Polarization diversity antenna arrays are applied to electronic support measures (ESM) systems since the 1980s. However, even today modern systems are conceived with the employment of the traditional and inconvenient spiral antennas and there are no studies that evidences most of the benefits of this technique applied to them. This paper aims at showing not only the advantages on polarization matching issues, but also the benefits in gain, in simpler truncation effect problems and in costs and time spent on design and production. After a brief approach strictly applied to ESM of the main features of spiral antennas and bow-tie antennas compounding a polarization diversity array, equations of the power available from the last were developed from the concept of effective length. The results demonstrate that the array could provide a power 8.7 dB higher than a modern spiral would to an ESM system when it receives vertical or horizontal linearly polarized waves, which multiplies by 2.7 the range of the system, besides also presenting a better performance in case of circularly polarized incident waves. This work has contributed to propose a replacement to the very common use of spiral antennas on the upcoming ESM system projects. This study is recommended for the areas of Electronic Warfare, Electromagnetic Devices and Applications and Ultra-Wideband Antennas.

Software-Defined Radio (SDR) technology has already cleared up passive radar applications. Nevertheless, until now, no work has pointed how this flexible radio could fully and directly exploit pulsed radar signals. This paper aims at introducing this field of study presenting not only an SDR-based radar-detector but also how it could be conceived on a low power consumption device as a tablet, which would make convenient a passive network to identify and localize aircraft as a redundancy to the conventional air traffic control in adverse situations. After a brief approach of the main features of the equipment, as well as of the developed processing script, indoor experiments took place. Their results demonstrate that the processing of pulsed radar signal allows emitters to be identified when a local database is confronted. All this commitment has contributed to a greater proposal of an Electronic Intelligence (ELINT) or Electronic Support Measures (ESM) system embedded on a tablet, presenting characteristics of portability and furtiveness. This study is suggested for the areas of Software-Defined Radio, Electronic Warfare, Electromagnetic Devices and Radar Signal Processing.