Transverse Electromagnetic Horn Antenna Research Articles

Ultrawideband 3-D Printed Endfire TEM Horn Antenna Mounted on a Cylinder Conductor

An ultrawideband, three-dimensional (3-D) printed end-fire transverse electromagnetic (TEM) horn antenna mounted on a cylinder conductor is proposed. The system consists of four TEM horn antennas and a cylinder conductor. The proposed TEM horn antenna is composed of four parts: a metal exponential curve, a trapezoidal metal top cover, a cylindrical ground, and a metal ridge. To enhance impedance bandwidth and radiation characteristics, a metal ridge is introduced on the cylinder ground plane. To verify the proposed antenna, a prototype is 3-D printed with surface metallization. The proposed antenna has a broad bandwidth from 1 to 16 GHz (16:1) with a voltage standing wave rate (VSWR) < 2 and a profile of 0.134λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> (λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> being the free-space wavelength at the lowest frequency). A good radiation pattern is obtained over the impedance bandwidth, and the measured gain ranges from 3.5 dBi to 11.5 dBi.

High power balanced TEM horn antenna for ultra wide band radiator

AbstractA balanced transverse electromagnetic (TEM) horn type antenna is designed and developed for a 120 kV, 66 Ω high power ultra wideband (UWB) radiator. This antenna consists of a coaxial to parallel plate unzipper BALUN followed by an exponentially tapered TEM horn structure. Analysis of this antenna in time and frequency domain is performed using CST Microwave Studio. This antenna is having a power handling capacity of 1000 MW, with percentage bandwidth of 167%. This antenna has a gain of ~10 dB at 1 GHz frequency. Return loss performance of better than −10 dB is observed in 150 MHz to 1 GHz frequency range. Effective radiation of short pulses (&lt;5 ns) with very fast rise time (300–500 ps) has been demonstrated using this high‐power antenna. Practical results at 220 MW power are presented in this article. Directional performance of this antenna is practically established through peak power patterns in horizontal and vertical plane.

A transient electromagnetic disturbance testing system based on low-frequency-compensated symmetric TEM horn antenna.

A transient electromagnetic disturbance (TED) testing system with an adjustable direction of polarization is developed in terms of a low-frequency-compensated symmetric transverse electromagnetic (TEM) horn antenna in this paper. TEM horn antennas are deficient in the low-frequency radiation, which would lead to a very narrow pulse width and cannot be directly applied in radiation tests of TED, especially the TED with abundant low-frequency components such as fast transient overvoltage and high-altitude electromagnetic pulse. To address this problem, a theoretical radiation model and a design principle of the back-loading method are proposed to compensate for the low-frequency performance. After the optimization of the structure according to the simulated results, a TED testing system with the aperture width of 0.9 m and the length of 1.8 m is built. The rise time of the electric field measured at the center of the aperture is 2.39 ns, the pulse width is 27.65 ns, and the peak field is over 50 kV/m, which can meet the requirements of relative standards. The dimension of the working volume is estimated as 0.4 × 0.5 × 0.5 m3 according to the field distribution.

A 3‐D Printed PCB Integrated TEM Horn Antenna

AbstractThis paper presents a very broadband (5–40 GHz) novel three dimension (3‐D) printed Transverse ElectroMagnetic (TEM) horn antenna. It is integrated with a planar Printed Circuit Board and radiates in a perpendicular direction of the Printed Circuit Board. The described antenna provides benefits in terms of cost and size for a two dimensional antenna array. Here the antenna and its corresponding transition to a regular 50 Ω microstrip line through Parallel Plate Waveguide and a 90° bend are presented. Prototypes of back‐to‐back transitions and antenna are fabricated and measured. The antenna has a return loss below −10 dB and a gain of approximately 10 dBi over the targeted frequency range.

An Active 20-MHz to 2.5-GHz UWB Receiver Antenna System Using a TEM Horn

An ultrawideband receiver antenna system is proposed. The radiating element is a transverse electromagnetic horn antenna, featuring a negative impedance converter at lower frequencies. The voltage standing-wave ratio (VSWR) is less than 2.0 in the bandwidth from 20 MHz to 2.5 GHz. A good agreement between the measurements of the fabricated system and the simulated results is observed. Sample applications include direction finding, broadband communication systems, radar systems, and electromagnetic compatibility measurement systems.

Miniaturization of TEM Horn Using Spherical Modes Engineering

The spherical mode expansion is exploited to miniaturize a transverse electromagnetic (TEM) horn antenna and achieve good frequency and time domain performances. To adjust the radiated powers of fundamental transverse electric and transverse magnetic modes, the combined loop and TEM horn antenna is engineered. The constructive combination of the two modes below the horn’s turn-on frequency miniaturizes the antenna and improves its gain. The magnitude and phase tuning of the desired modes is achieved by modifying the loop’s geometry. The spherical modal spectrum at higher frequencies is also studied and the antenna’s geometry is further modified to maintain constructive interference between the higher order spherical modes. A prototype with electrical size of $0.188~\lambda ~\times0.145\lambda ~\times0.087\lambda $ (length $\times $ width $\times $ height) at the turn-on frequency is fabricated over a ground plane. Over three times lower turn-on frequency is obtained compared to a conventional TEM horn with up to 9 dB improvement in the realized gain at the low end and better radiation characteristics over more than 5:1 bandwidth (from 0.87 to 4.5 GHz). Unidirectional operation with front to back ratio >9 dB and excellent time-domain performance with fidelity factor >95% over wide field of view are also demonstrated.

UWB TEM horn antenna for the asphalt pavement investigation

A simple Ultra-WideBand (UWB) exponentially-tapered Transverse ElectroMagnetic (TEM) horn antenna is presented for the asphalt detection based on Ground Penetrating Radar (GPR). In order to reduce the reflections from the antenna aperture, some absorbing material is loaded on the outer surface of the conductor. Comparing with the traditional TEM horn antenna, the proposed antenna has a small size and a large impedance bandwidth. Simulated and measured results show that the proposed TEM horn antenna has a low Voltage Standing Wave Ratio (VSWR) below 2 over the whole band from 0.35 GHz to 12 GHz, good radiation characteristics, and small late-time ringing, which can perfectly meet the requirements of the GPR application.

A New Type of TEM Horn Antenna for High-Altitude Electromagnetic Pulse Simulator

A new type of transverse electromagnetic (TEM) horn antenna for high-altitude electromagnetic pulse (HEMP) simulator is designed in terms of the structure of circular helix end and shielded plates circuit. The finite-difference time-domain (FDTD) method is applied to build the antenna model and to calculate waveforms of antenna radiation filed. Results suggest that the new type of antenna can broaden the pulse width and raise the peak field strength value of radiated pulses. Furthermore, the improvement of radiation in lower frequencies reaches a degree of several decibels in amplitude frequency spectrum. Meanwhile, a new index called “waveform similarity” for confirming the similarity of field waveforms with that of standard specification is proposed and calculated for near-field waveforms of different TEM horn antennas. It is shown by the new index that the field waveform radiated by the new type of TEM horn antenna is much closer to standard waveform.

Radiation Pattern Measurements of an Integrated Transverse Electromagnetic Horn Antenna Using a Terahertz Photomixing Setup

We report experimental radiation pattern measurements of a transverse electromagnetic horn antenna at the millimetric/sub-millimetric frontier (280–350 GHz). The antenna is fed by a monolithically integrated uni-travelling-carrier photodiode illuminated by an optical beatnote (photomixing) at 1.55 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\mu{\rm m}$</tex></formula> . The detection is performed using an electronic sub-harmonic mixer and the whole characterization system is working at room temperature. Radiation patterns are measured in the <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${\rm E}$</tex></formula> -plane and compared with electromagnetic simulations with a good agreement.

Wide-band continuous-wave terahertz source with a vertically integrated photomixer

A transverse electromagnetic horn antenna is monolithically integrated with a low temperature grown GaAs vertical photodetector on a silicon substrate forming a vertically integrated photomixer. Continuous-wave terahertz radiation is generated at frequencies up to 3.5 THz with a power level reaching 20 nW around 3 THz. Microwave and material concepts allow both qualitative and quantitative explanations of the experimental results. The thin film microstrip line topology has been adapted for active devices by an Au–Au thermocompression layer transfer technique and seems to be a promising generic tool for a new generation of efficient terahertz devices.

Continuous terahertz-wave generation using a monolithically integrated horn antenna

A transverse electromagnetic horn antenna is monolithically integrated with a standard ultrafast interdigitated electrode photodetector on low-temperature-grown GaAs. Continuous-wave terahertz radiation is generated at frequencies up to 2 THz with a maximum power of approximately 1 μW at 780 GHz. Experimental variations in the terahertz power as function of the frequency are explained by means of electromagnetic simulations of the antenna and the photomixer vicinity.

Integrated terahertz TEM horn antenna

A terahertz transverse electromagnetic horn antenna (THz-TEMHA) monolithically integrated on a gallium arsenide substrate has been studied by means of subpicosecond pulses generated and measured on a 50 Omega coplanar waveguide. The measured reflection coefficient is below -10 dB from 100 GHz to about 1 THz. A terahertz ranging experiment was carried out in a monostatic configuration

Design of an ultrawide-band TEM horn antenna with a microstrip-type balun

An exponentially tapered ultrawide-band transverse electromagnetic (TEM) horn antenna having a microstrip-type balun is designed. The balun is used to improve the impedance characteristic of a TEM horn antenna. The measured bandwidth for VSWR less than 2.0 ranges from 67.94 to 1573.9 MHz. The bandwidth of the proposed TEM horn is three times wider than that of the linearly tapered TEM horn. The designed antenna can be used not only for electromagnetic compatibility measurement but also for broad-band communication system.

A compact former of high-power bipolar subnanosecond pulses

The system comprises either a nanosecond solid-state operating switch (SOS)-generator (see, e.g., Rukin, 1995) or a RADAN pulsed power source (see, e.g., Mesyats et al., 1993) that charges resonantly a short pulse-forming line (PFL) through a decoupling inductor, an active converter, a matched load, and several built-in voltage and current probes. The active converter comprises an additional 1-ns PFL charged through a peaking spark gap (SG) and a secondary decoupling inductor by the first PFL, and two SGs (chopping and peaking gap). The peaking SG and active converter are set in one body and operate in N/sub 2/ at pressure up to 6 MPa. Driven by RADAN, the converter generates bipolar subnanosecond pulses having peak-to-peak amplitude up to 270 kV across 46.6-/spl Omega/ load. The pulsewidth of each half wave of bipolar pulses on full-width at half-maximum is 280 ps, with the risetime of the first half wave of about 160 ps. The SGs' gaps can be regulated without system depressurizing (a technique adopted from Shpak et al., 1996). Circuit analysis accounting for the distributed character of the components and numerous parasitic parameters is presented. Mapping of main SG parameters (gap distance and pressure) was performed. Waveforms probed at different locations of the pulser systems, from the SOS-generator and from the RADAN to the load, are shown. The bipolar subnanosecond pulses had very stable rise, while the fall jitter was around 50 ps. The experimental results are in fair agreement with the simulation. Pulsers were tested with a transverse electromagnetic horn antenna. An effective potential of 910 kV was obtained.

Modeling of ground-penetrating Radar for accurate characterization of subsurface electric properties

The possibility to estimate accurately the subsurface electric properties from ground-penetrating radar (GPR) signals using inverse modeling is obstructed by the appropriateness of the forward model describing the GPR subsurface system. In this paper, we improved the recently developed approach of Lambot et al. whose success relies on a stepped-frequency continuous-wave (SFCW) radar combined with an off-ground monostatic transverse electromagnetic horn antenna. This radar configuration enables realistic and efficient forward modeling. We included in the initial model: 1) the multiple reflections occurring between the antenna and the soil surface using a positive feedback loop in the antenna block diagram and 2) the frequency dependence of the electric properties using a local linear approximation of the Debye model. The model was validated in laboratory conditions on a tank filled with a two-layered sand subject to different water contents. Results showed remarkable agreement between the measured and modeled Green's functions. Model inversion for the dielectric permittivity further demonstrated the accuracy of the method. Inversion for the electric conductivity led to less satisfactory results. However, a sensitivity analysis demonstrated the good stability properties of the inverse solution and put forward the necessity to reduce the remaining clutter by a factor 10. This may partly be achieved through a better characterization of the antenna transfer functions and by performing measurements in an environment without close extraneous scatterers.

Design of an exponentially‐tapered TEM horn antenna for the wide broadband communication

AbstractA transverse electromagnetic (TEM) horn antenna is designed and realized using exponentially tapered conductor flares for wireless communications. This exponentially tapered structure of the flares decreases the impedance mismatching a lot and reduces the size and cost of the TEM horn. The VSWR of the antenna is less than 2 in the frequency band of 74.4 MHz to 1.19 GHz, and its gain is more than 8.3 dBi over 200 MHz. Those performances show that the designed TEM horn antenna has wide broadband characteristics. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 531–534, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20025

A design study for the basic TEM horn antenna

In this paper, a design study was performed for the basic TEM horn antenna. In the theoretical model, care was taken to avoid the problems associated with the use of gap sources when calculating the reflection coefficient and input impedance of the antenna. All numerical calculations were made with a program based on the method of moments, and the accuracy of the numerical calculations was established with measured results for selected antennas. The transverse electromagnetic (TEM) horn antenna is a popular broadband antenna. The basic antenna has a simple design consisting of two triangular plates and a feeding structure. The horn is described completely by only three variables: /spl alpha/, /spl beta/, and s. /spl alpha/ is the angular width of each plate, /spl beta/ is the angular separation between the two plates, and s is the length, measured from the drive point to the corner of the plate. The geometry of the basic TEM horn antenna does not require a particular choice of a feeding method.

On the Characteristic Impedance of the TEM Horn Antenna

Some time ago, Carrel presented an analytical formula, based on conformal mapping, for the characteristic impedance of the transverse electromagnetic horn antenna . Later, results from this formula were shown to be in error, and Lambert et al. offered a new analytical formula, also based on conformal mapping . This formula also contains an error that is easily corrected. Independently, Yang and Lee offered an analytical formula . In this paper, we compare these analytical formulas to a direct numerical solution. Finally, we compare the "microstrip approximation" for the characteristic impedance to the exact solution. Graphs are presented for the characteristic impedance versus the angles of the horn that should be useful for the purpose of design.

Time-domain antenna characterizations

A set of time-domain characterizations that can efficiently describe wireband antennas is proposed. The experimentally measured responses of transverse electromagnetic horn antennas are used to evaluate the utility of these characterizations. Comparisons are made between the antennas' frequency-domain response and their time-domain characterizations. The comparisons show that the time-domain characterizations can provide significant insight into an antenna's behavior as well as providing a means to accurately compare two or more different antennas. >