TEM Horn Antenna Research Articles

Vulnerability of Smart Grid-enabled Protection Relays to IEMI

Abstract. The electricity sector has been undergoing transformations towards the smart grid concept, which aims to improve the robustness, efficiency, and flexibility of the power system. This transition has been achieved by the introduction of smart electronic devices (SEDs) and advanced automatic control and communication systems. Despite the benefits of such modernization, safety issues have emerged with significant concern by experts and entities worldwide. One of these issues is known as Intentional Electromagnetic Interference (IEMI), where offenders employ high-power electromagnetic sources to maliciously disrupt or damage electronic devices. One of the possible gateways for IEMI attacks targeting the smart grids is the microprocessor-based protection relays. On the one hand, the malfunctioning of these devices can lead to equipment damage, including high-voltage equipment (e.g., power transformers), which represent one of the most high-cost items of energy infrastructure. On the other hand, a possible misleading triggering of these devices could cause cascading effects along the various nodes of the power system, resulting in widespread blackouts. Thus, this study presents the possible recurring effects of IEMI exposure of a typical protection relay used in smart grid substations as part of the SCADA (Supervisory Control and Data Acquisition) system. For this purpose, a test setup containing a smart grid protective unit, a monitoring box, and the device's wiring harness is exposed to radiated IEMI threats with high-power narrowband signals using a TEM waveguide and horn antennas. The effects during the test campaigns are observed by means of an IEMI-hardened camera system and a software developed to real-time monitor the device's fibre optic communication link, which is established according to the IEC 60870-5-105 protocol. The results revealed failures ranging from display deviation to various types of protection relay shutdown. Moreover, the consequences of the identified failures in a power substation are discussed to feed into a risk analysis regarding the threat of IEMI to power infrastructures.

Magnetic Field Distribution in Aperture of TEM Horn Antenna for Close Proximity RF Immunity Test by Impulsive Excitation Wave

Magnetic Field Distribution in Aperture of TEM Horn Antenna for Close Proximity RF Immunity Test by Impulsive Excitation Wave

Evaluation of a TEM horn antenna for radiated immunity tests in close proximity

Evaluation of a TEM horn antenna for radiated immunity tests in close proximity

Applying of Luneburg lens for multi‐beam TEM‐horn antenna

Here, a multi-beam TEM-horn antenna with beam direction is proposed. Presented construction allows obtaining scanning beam and complicated antenna patterns, thus it can be used as substitute of ultra-wideband phased array antennas.

Robust Design of 3D-Printed 6–18 GHz Double-Ridged TEM Horn Antenna

A robust design of a 3D-printed 6–18 GHz double-ridged TEM horn antenna is proposed in this paper. The designed TEM horn antenna has two parts: an adaptor and a horn aperture. The adaptor is realized using a double-ridged waveguide to extend the operating bandwidth of the dominant mode (TE10 mode). Meanwhile, the horn aperture section is implemented in an exponentially tapered configuration to match the impedance of the double-ridged waveguide with the intrinsic impedance. The performance of the initially designed antenna shows that the reflection coefficient and gain levels are less than −13 dB and greater than 5.5 dBi within the 6–18 GHz band, respectively. The initial design was well done, but the noise factors that may occur during the manufacturing process were not taken into account. To design an antenna considering these noise factors, the parameters of the initial design are optimized by a novel robust design method also proposed in this paper. The robustness of the antenna optimized by the proposed method is approximately 12.4% higher than that of the initial antenna. The validity of the proposed method was tested by fabricating the antenna. A prototype of the optimized antenna with the proposed robust design method is fabricated using a 3D printer with a stereolithographic apparatus attached, and the surface of the frame is covered by a nano-silver plating. The measured results of the fabricated antenna are in good agreement with the simulation results over the operating band. The measured −10 dB reflection coefficient bandwidth of the antenna can cover 6–18 GHz. In addition, the measured gain ranges from 4.42 to 10.75 dBi within the 6–18 GHz band.

Wideband Frequency-Domain and Space-Domain Pattern Reconfigurable Circular Antenna Array

This paper presents a wideband circular antenna array with a frequency-domain and space-domain reconfigurable radiation pattern. A wideband circular array antenna is designed with omnidirectional radiation pattern, in azimuth direction, throughout the whole frequency band. The antenna array consists of eight TEM horn antennas. The antenna array exhibits an omnidirectional azimuthal radiation pattern when all eight ports are excited with signals of the same magnitude and phase. The antenna array is fed through eight reconfigurable bandstop filters and a power splitter. This enables it to provide an omnidirectional azimuthal pattern along with a single directional pattern null in a given spatial direction and at a certain frequency. Both the spatial direction and the frequency can be altered. The antenna works from 0.8 to 3 GHz. The antenna array will be useful in combating interference in wideband communication systems. It will also be of value in surveillance military applications.

A software controllable modular RF signal generator with multichannel transmission capabilities.

A software controllable system which generates and transmits user defined RF signals is discussed. The system is implemented with multiple, modular transmitting channels that allow the user to easily replace parts such as amplifiers or antennas. Each channel is comprised of a data pattern generator (DPG), a digital to analog converter (DAC), a power amplifier, and a transmitting antenna. All channels are controlled through a host PC and synchronized through a master clock signal provided to each DAC by an external clock source. Signals to be transmitted are generated through the DPG control software on the PC or can be created by the user in a numerical computing environment. Three experiments are discussed using a two- and four-channel antenna array incorporating Chebyshev tapered TEM horn antennas. Transmitting distinct sets of nonperiodic bipolar impulses through each of the antennas in the array enabled synthesizing a sinusoidal signal of specific frequency in free space. Opposite to the standard phased array approach, each antenna radiates a distinctly different signal rather than the same signal simply phase shifted. The presented approach may be employed as a physical layer of encryption dependent on the position of the receiving antenna.

From exponential line to TEM horn and Vivaldi antenna

From exponential line to TEM horn and Vivaldi antenna

Numerical estimation for TEM horn antennas with transmission line taper shapes

Numerical estimation for TEM horn antennas with transmission line taper shapes

Dielectric loaded TEM horn-fed ridged horn antenna designfor ultrawideband ground-penetrating impulse radar

A modified double-ridged horn structure is proposed to obtain ultrawideband antenna characteristics over a bandwidth ratio of greater than 40:1 for impulse radar systems. The Vivaldi-shaped TEM horn feeder has been designed to extend the lower cut-off frequency and the partial dielectric loading technique using a small lens inward while the aperture has been implemented to enhance the gain of the standard double-ridged horn antenna without changing the physical dimensions. The starting frequency of the antenna operation band is lowered from 800 MHz to 400 MHz. Moreover, approximately 5 dB gain increment level is achieved from 4 to 10 GHz. It is shown that proper combination of the partial dielectric loaded TEM and ridged horn antennas can be suitable for multiband ground-penetrating radar operations that provide high resolution imaging at different depths. The antenna gain and input reflection performance measurements are presented with comparisons in both the frequency and time domains.

A Novel UWB TEM Horn Antenna with a Microstrip-Type Feed

A novel ultra-wideband (UWB) TEM horn antenna fed by a microstrip-type transition is designed. The feeding structure is directly realized by a microstrip line with the merit of compact size and UWB. To broaden the low frequency band, an arc surface is added at the end of the flare plates. Numerical simulation is applied to discuss the effect of the geometry construction which contains the microstrip-type transition and the circular arc surface at the end of radiating arm. Return loss, radiation pattern, and gain of the fabricated antennas are measured. The measured results show that the antenna yields a wide bandwidth ranging from 1 GHZ to 10.3 GHz with return loss less than −10 dB. The antenna also achieves unidirectional radiation patterns with stable antenna gain. These characteristics imply that the compact antenna may be used for detecting buried objects in the wall or UWB communication systems of band like GSM, Wi-Fi, and so forth.

Nanosecond High-Voltage Pulse Generator Using a Spiral Blumlein PFL for Electromagnetic Interference Test

High-power electromagnetic (HPEM) pulse can be delivered to electronic equipment in two ways. One is through the application of radiated fields, and the other is through conduction along cables and wires. In this paper, a high-voltage pulse generator using a spiral Blumlein pulse forming line (PFL) was developed for the test of HPEM effect by radiation and conduction. For the conduction test, a spiral strip Blumlein PFL filled with transformer oil is employed to generate high voltage (>300 kV) and long duration (50 ns) pulse. High-power ultrawideband pulse for the radiation test was generated by combining a TEM horn antenna with the high-voltage generator. The peak-to-peak value of electric field intensity of a radiated pulse is 53.3 kV/m at a distance of 10 m away from the antenna. The pulse generation system was used for the examination of effects of the electric fields and conducted pulses on the operation of electronic devices.

절연재에 따른 TEM 안테나의 방사패턴 및 이득 변화

Abstract - TEM Horn antenna is typically used in HPEM area. It is necessary to apply a high voltage of the antenna for radiating HPEM. Then, it is necessary to insulate essentially of applying a high voltage to the antenna. At this time, radiation pattern and gain of the TEM Antenna is changed. For this reason, it is necessary to analyze changing characteristics by using simulation. In this paper, I analyzed the radiation pattern of the antenna in accordance with the lens and insulating material. As a result, it was observed that the value of the gain is changed in accordance with the frequency. The lens is used for the antenna, the gain characteristic is improved.Key Words : TEM horn antenna, TEM antenna insulation, Far-field pattern † Corresponding Author : Dept. of Electrical Engineering, INHA University, KoreaE-mail : cshuh@inha.ac.kr* Dept. of Electrical Engineering, INHA University, Korea** Agency for Defense Development***Korea Testing & Research Institute, (KTR)Received : December 10, 2013; Accepted : March 31, 2014

Analysis of Omnidirectional Dual-Reflector Antenna and Feeding Horn Using Method of Moments

A hybrid numerical technique is applied for the analysis of circularly symmetric dual reflector antenna fed by TEM coaxial horn to generate an omnidirectional radiation pattern. By following the steps of a technique developed for the analysis of horn antennas, it employs a stepped-waveguide method to analyze the interior surfaces of the TEM coaxial horn transition and the electric field integral equation (EFIE) is applied on the outer surfaces of the TEM coaxial horn including the radiating aperture and the reflectors. Simultaneously, the magnetic field integral equation (MFIE) is employed on the aperture to relate the aperture fields and those in the horn transition. Method of moments (MoM) is employed to numerically solve the resultant hybrid field integral equation. The technique is applied for electromagnetic analysis of a coaxial TEM horn antenna and an omnidirectional dual reflector antenna. Results for the antenna return loss at the input port and for the vertical radiation pattern are given and compared with measurements and with commercial software results.

Generation of Ultrawide Band Electromagnetic Pulse from Blumlein Pulse Forming Line

A high voltage pulse generator was fabricated to radiate ultrawide band electromagnetic pulse. A coaxial type of Blumlein pulse forming line is employed to produce a pulse of high voltage (>300 kV) and short pulse duration (~5 ns). A helical strip/wire type of air-cored pulse transformer was used to charge the Blumlein pulse forming line up to more than 300 kV. A peaking switch is essential to make the pulse rise time as fast as possible. Typically, the rise time is ~500 ps. The output pulse of the generator is radiated into air through an exponentially tapered TEM horn antenna. The electric field intensity of a radiated pulse was measured as a function of the distance from the transmitting horn as well as the output voltage of the peaking switch. The peak-to-peak value of the electric field intensity at 10 m from the TEM antenna was~100 kV/m.

A Compact Vivaldi Shaped Partially Dielectric Loaded TEM Horn Antenna for UWB Communication

Ultrawideband (UWB) antennas are of huge demand and Vivaldi antennas as well as the TEM horn antennas are good candidates for UWB applications as they both have relatively simple geometry and high gain over a wide bandwidth. The aim of this study is to design a compact antenna that achieves maximum gain over a bandwidth between 1.5 and 10.6 GHz while minimizing its size. The idea is to make use of combined respective advantages of Vivaldi and TEM horn antennas to achieve the desired goals by shaping the TEM horn antenna to look like a Vivaldi antenna. The antenna structure is modified by a dielectric load in the center to increase the gain bandwidth. It is placed in a surrounding box made of PEC material to reduce the undesired side lobes and to obtain more directive radiation pattern. The simulations are performed by using the CST STUDIO SUITE electromagnetic (EM) simulation software and they are later verified by the actual measurements. The Vivaldi shaped partially dielectric loaded (VS-PDL) TEM horn antenna is proposed as a compact UWB antenna for systems using the newly established UWB band and also for the communication systems of popular bands like ISM, Wi-Fi, and GSM.

辐射式核电磁脉冲模拟器TEM喇叭天线

For the problem that TEM horn antenna used in the radiating-wave nuclear electromagnetic pulse (NEMP) simulator has limited ability of low frequency radiating, two basic types of TEM horn antennas (composed of plates and wires respectively) are analyzed. Based on TEM horn antenna composed of wires that can make simulator lighter, a new type of TEM horn antenna is designed by using the structure of helixes end and attaching the shielded plates circuit to antenna. Results show that compared with the common type of the TEM horn antenna composed of wires, this new type of antenna has improved the ability of low frequency radiating greatly. The pulse width of near field waveform is longer by almost seven nanoseconds, and the peak value of pulse is larger by almost one kilovolt per meter. Increasing the radius of helixes and decreasing the pitch of helixes can further enhance both pulse width and peak value of the field strength. Meanwhile, attaching the shielded plates circuit to antenna can further lower down the wave crest generated by reflected signals, which makes the near field waveforms much better.

TEM Horn Antenna Loaded With Absorbing Material for GPR Applications

A novel exponentially tapered TEM horn antenna is presented. It is fed directly by a coax through a compact transition section and possesses a wide bandwidth, good radiation characteristic, and easy integration with microwave circuits. Two specially tapered metal flares have been designed to make a wideband characteristic and reduce the reflection. To overcome aperture reflections at low frequencies and unbalanced aperture field at higher frequencies, an arc surface is added at the end of the flare plates, and an absorbing material is loaded on the outer surface of the flare section. Measured results show that the presented antenna has a wide bandwidth from 0.83 to more than 12.8 GHz under a return loss <;-10 dB, small input reflection, a moderate gain from 0 dBi at 0.83 GHz to 10 dBi at 12 GHz, and a good radiation characteristics in the time domain, which can be suitable for ground penetrating radar (GPR) applications.

切比雪夫渐变线TEM喇叭天线数值模拟

切比雪夫渐变线TEM喇叭天线数值模拟

Design and Fabrication of a Novel Ultrawideband Combined Antenna

In this letter, design and fabrication of an ultrawideband combined antenna are presented. Actually, this element is a combination of a TEM horn antenna and some magnetic dipoles. The combination of radiation fields due to these elements causes reduction in reactive energy around the antenna, and with this method, the antenna matching in a wide frequency band becomes possible. The bandwidth is further improved by tapering the radiation part of the antenna exponentially. Also, proposing a novel transition structure from coaxial cable to the antenna, the discontinuity the wave faces is reduced and, finally, a bandwidth of 180 MHz-30 GHz is obtained for this structure. The fabrication results for this antenna verify simulation results. The plots of return loss and radiation pattern at several frequencies will be presented. Finite integral-based CST software is utilized for simulation.