Vee Dipole Research Articles

The Ultrawideband Elliptical Resistively Loaded Vee Dipole

We present the development of the novel elliptical resistively loaded vee dipole (ERLVD). By replacing the constituent subelements with ellipses, the ERLVD has two degrees of design freedom to achieve increased gain, bandwidth, and decreased size compared with the classical resistively loaded vee dipole (RLVD). The prototyped ERLVD with a unity growth rate experimentally achieved a bandwidth ratio of 13:1 (0.49–6.41 GHz) and a smaller arm length of $0.17~\lambda _{\mathrm {low}}$ at 490 MHz. This ERLVD has twice larger the bandwidth ratio, 2–3 dB higher gain, and smaller arm size at 490 MHz compared to similar RLVDs. The second ERLVD with a higher growth rate can achieve much higher relative gain increases of 7–8.5 dB with slightly reduced bandwidth.

Reconfigurable Multi-Beam Dual-Band Antenna based on Vee Dipoles


 
 
 This paper presents a novel antenna configuration to support reconfigurable multi-beam feature with dual-band capability. The proposed design uses four double Vee dipoles with their arms printed on either sides of a substrate and fed through a single coaxial input probe. A single directional beam that can be configured in four directions at quadrature angle in the azimuth (xy-plane) and corresponding dual, triple and quad beams have been obtained by controlling the state of four PIN diodes. A prototype of the proposed antenna has been designed and fabricated. Measured antenna parameters are in good agreement with that of simulated parameters. This highly planar antenna shows similar radiation patterns at both design frequencies enabling concurrent dual-band communication for all fifteen possible beam configurations.
 
 

Non-Foster Matching of a Resistively Loaded Vee Dipole Antenna Using Operational Amplifiers

A non-Foster matching network using negative impedance converters (NICs) is proposed for a resistively loaded vee dipole antenna (RVD). The RVD suffers from considerable reflection at the feeding transmission line at low frequencies because of its large negative input reactance. To reduce the reflection, a non-Foster matching network, which is composed of NICs based on operational amplifiers (op-amps), is proposed. For the practical design, the effects of input parasitic capacitances of the op-amp and the finite open-loop gain are considered. The stability analysis is performed according to the Barkhausen stability criterion. The non-Foster matching network is implemented with the RVD as a load. The measured impedance demonstrates that the matching network significantly reduces the input reactance of the RVD. In the time-domain analysis, the matched RVD is shown to reflect significantly less incident pulse. A target was imaged through a series of radar echo experiments. The images show that the non-Foster matching network enhances the performance of the RVD as an antenna for the ground-penetrating radar.

네거티브 임피던스 변환기에 기반을 둔 저항성 V 다이폴 안테나의 논 포스터 임피던스 매칭

네거티브 임피던스 변환기에 기반을 둔 저항성 V 다이폴 안테나의 논 포스터 임피던스 매칭

Ultra-Wideband Impedance Matching Technique for Resistively Loaded Vee Dipole Antenna

The resistively loaded vee dipole (RVD) antenna has many advantages as an ultra-wideband (UWB) radar antenna, especially ground-penetrating radar. However, it has the drawback of having considerable reflections at the feed point due to an impedance mismatch between the antenna and the feeding transmission line. In this communication, a matching network is proposed to reduce the reflection and the design procedure is presented. The network is composed of two L-sections in cascade: an inductive L-section for high frequency matching and a high-pass type L-section for low frequency matching. It is demonstrated that the high-pass type L-section hardly destroys the high frequency matching. The RVD with the proposed matching network is implemented and the performance is measured. The results show that the RVD is matched over the desired band of 500 MHz-3 GHz, and more energy is radiated in the main pulse.

안테나 수치 해석 모델을 이용한 저항성 V 다이폴의 효율 분석

A method of moments model for the resistive vee dipole has been established. In order to validate the numerical model, an experimental model is built and reflections from the antenna in the feed line are measured. The measured data and the numerical data agree closely validating the numerical model. Based on the numerical model, efficiency of the antenna and the power dissipated in the resistors are analyzed. The results show that the antenna has low radiation efficiency because of the loading resistors and that the resistors near the drive point of the antenna dissipate more power than do the resisters far from the drive point. The results can be used to determine the amount of power that can be accepted by the resistive vee dipole, to determine the power rating of the loading resistors for a desired application, or to estimate the operation range of the antenna.

Analysis of thin-wire ground penetrating radar systems for buried target detection, using a hybrid MoM-FDTD technique

A hybrid method combining the finite difference time domain (FDTD) method and the method of moments (MoM) in the frequency domain is proposed to model the electromagnetic behavior of a realistic ground penetrating radar (GPR) system. The GPR is a non-destructive testing (NDT) technique. It consists of a broadband thin-wire vee-dipole antenna located in the vicinity of a lossy ground containing unexploded ordnances. In the solution of the problem, we identify two sub-problems, namely, the antenna problem and the ground buried object problem. Capabilities of the MoM for solution of the governing thin-wire electric field integral equation of the antenna problem and general FDTD solution of Maxwell's equations posed by the scattering of arbitrary shape objects in multilayered media are combined to efficiently and accurately simulate the electromagnetic operation of the system. The proposed simulation technique is validated against the original MoM solution of the problem. It is shown that the proposed hybrid technique exhibits superior performance based on both computation time and numerical accuracy compared with the conventional FDTD and MoM solution techniques. It is also shown that the position and size of the target, as well as the electromagnetic characteristics of the target, can be determined using a simple signal processing technique.

Efficiency of resistive vee dipole antenna

The efficiency of the resistive vee dipole antenna, the arms of which are loaded with surface-mount chip resistors according to the modified Wu-King profile, is obtained numerically. The numerical model is based on the method of moments and validated by a set of reflection measurements. The numerical model is used to obtain the radiation efficiency and the power dissipated in each chip resistor. Results show that the antenna has low radiation efficiency because the chip resistors dissipate a significant portion of input power. The results may be used to determine the amount of input power that can be handled by the antenna or the resistor types that can handle the power required for a desired application.

Design of a resistively loaded vee dipole for ultrawide-band ground-penetrating Radar applications

A new resistively loaded vee dipole (RVD) is designed and implemented for ultrawide-band short-pulse ground-penetrating radar (GPR) applications. The new RVD is improved in terms of voltage standing wave ratio, gain, and front-to-back ratio while maintaining many advantages of the typical RVD, such as the ability to radiate a short-pulse into a small spot on the ground, a low radar cross section, applicability in an array, etc. The improvements are achieved by curving the arms and modifying the Wu-King loading profile. The curve and the loading profile are designed to decrease the reflection at the drive point of the antenna while increasing the forward gain. The new RVD is manufactured by printing the curved arms on a thin Kapton film and loading them with chip resistors, which approximate the continuous loading profile. The number of resistors is chosen such that the resonant frequency due to the resistor spacing occurs at a frequency higher than the operation bandwidth. The antenna and balun are made in a module by sandwiching them between two blocks of polystyrene foam, attaching a plastic support, and encasing the foam blocks in heat-sealable plastic. The antenna module is mechanically reliable without significant performance degradation. The use of the new RVD module in a GPR system is also demonstrated with an experiment.

Design and realization of a discretely loaded resistive vee dipole for ground‐penetrating radars

A discretely loaded resistive vee dipole (RVD) is designed and realized for use in ground‐penetrating radar (GPR) applications. The RVD is a good antenna for GPR applications because it can radiate a temporally short pulse into a small spot on the ground, and its low radar cross section mostly eliminates the multiple reflections between the surface of the ground and the antenna. The antenna presented in this paper is printed on a circuit board and is discretely loaded with off‐the‐shelf surface‐mount chip resistors. The resulting structure is easy and inexpensive to manufacture and is mechanically stable. The realized antenna is measured in terms of the radiated field and the reflected voltage in the feeding transmission line. The results are compared with those of the antenna with the same resistive loading without substrate. The effects of the transmission line impedance on the performance of the antenna are also presented.

Simulation of ultra‐wideband indoor propagation

AbstractA comprehensive simulation of ultra‐wideband signal propagation in indoor environments is presented. The simulation is based on time‐domain electromagnetic modeling of transmitting and receiving antennas and the analysis of wave propagation through indoor channels using the time‐domain uniform theory of diffraction. The antennas are a pair of TEM horns which are modeled as arrays of vee dipoles. The analysis of these antennas is performed directly in the time domain, without the need for transforming the solutions from the frequency domain to the time domain. The frequency dependence of materials utilized in the structure on the indoor channel is accounted for in the channel simulation. The simulation results are compared with the corresponding measured results. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 103–108, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20221

High-gain low-sidelobe double-vee dipoles

This paper introduces a novel variation of the vee dipole antenna consisting of two coplanar vee dipoles with a common feed point. It is referred to as a double-vee dipole. Radiation characteristics of the double-vee dipole antenna are investigated numerically and experimentally. It is shown that the double-vee dipole can provide significantly higher directivity and lower sidelobes and back radiation than the conventional vee dipole. With increasing arm length, the directivity of the double-vee dipole exhibits a series of local maxima. Measured and predicted radiation patterns for a fabricated double-vee dipole are presented and shown to be in good agreement.

Analysis of nu-dipole antennas using the method of moments

An analysis of the features of a novel antenna, the nu-dipole, is presented and its input characteristics compared with those of the vee-dipole antenna. By adapting the thin-wire approximation, the integro-differential equation formulated for the nu-dipole antenna problem is converted into a matrix equation by using the moment method based on Galerkin's procedure, in which the current expansion and testing functions are both triangle functions. Upon employing known matrix methods the current distribution on the antenna emerges from the solution of the matrix equation. Based on the obtained current distribution, the input admittance and power are evaluated and compared with those of the vee-dipole. For these results, the nu-dipole possesses higher amplitudes but at slightly higher resonant electrical lengths. The nu-dipole far-zone electric field pattern |E θ(θ,φ = 90°)| rotates as the electrical length is varied.

Land mine detection using a ground-penetrating radar based on resistively loaded Vee dipoles

Resistively loaded Vee dipoles are considered for use in a short-pulse ground penetrating radar (GPR) used to detect buried antipersonnel land mines. First, a study is made to select a short pulse to radiate that is most appropriate for the problem. A simple one-dimensional (1-D) analysis of some representative soils and a land mine is used to select a radiated pulse similar in shape to a differentiated Gaussian pulse with a spectral peak at 4 GHz. Based on previous studies, the conductivity of the arms of the Vee dipole is linearly tapered from the feed to the open ends. A fully three-dimensional (3-D) finite-difference time domain (FDTD) model is developed and used to simulate the GPR land mine detection problem. Using this model, a resistively loaded Vee dipole is selected and evaluated. Parametric studies related to the problem are conducted including: varying the height of the Vee above the ground, varying the position of the land mine both laterally and in depth, and examining the effects of the geometry of the land mine on the received signal. Environmental conditions are examined including signal returns from rocks and variations in the shape of the surface of the ground. The FDTD results are validated by comparisons with experimental data. These studies demonstrate that resistively loaded Vee dipoles can greatly reduce clutter related to the antenna, making the task of distinguishing land mines (targets) much easier.

Vee dipoles with resistive loading for short-pulse ground-penetrating radar

The worldwide crisis due to land mines has given rise to a need for better detection technologies. One means of detecting buried land mines is the short-pulse ground-penetrating radar (GPR). A short-pulse GPR system requires broadband directive antennas. Resistively loaded Vee dipoles, with either constant or linearly tapered conductivity, offer a simple means of achieving such antennas. Vee dipoles have greater directivities than conventional linear dipoles, and the resistive loading can greatly reduce unwanted signals (clutter) due to reflections from the open ends of the dipole arms and multiple reflections between the antenna and the surface of the ground. This clutter can obscure real targets. In most cases, the Vee dipole with a linearly tapered conductivity offers the best performance. © 1996 John Wiley & Sons, Inc.