An investigation of the design of a log-periodic dipole array with low side-lobe levels for broadcast applications

Baker, D.C.; Reuss, T.

doi:10.1109/11.52368

Cited by 7 publications

(4 citation statements)

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“…Let us mention the engineering application of antennas using log-periodic electromagnetic antennas [129,130,131,132,133,134,135]. The DSI structure provides an optimal compromise between maximizing bandwidth and radiation efficiency.…”

Section: Log-periodic Antennasmentioning

confidence: 99%

Discrete-scale invariance and complex dimensions

1998

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Abstract:We discuss the concept of discrete scale invariance and how it leads to complex critical exponents (or dimensions), i.e. to the log-periodic corrections to scaling. After their initial suggestion as formal solutions of renormalization group equations in the seventies, complex exponents have been studied in the eighties in relation to various problems of physics embedded in hierarchical systems. Only recently has it been realized that discrete scale invariance and its associated complex exponents may appear "spontaneously" in euclidean systems, i.e. without the need for a pre-existing hierarchy. Examples are diffusion-limited-aggregation clusters, rupture in heterogeneous systems, earthquakes, animals (a generalization of percolation) among many other systems. We review the known mechanisms for the spontaneous generation of discrete scale invariance and provide an extensive list of situations where complex exponents have been found. This is done in order to provide a basis for a better fundamental understanding of discrete scale invariance. The main motivation to study discrete scale invariance and its signatures is that it provides new insights in the underlying mechanisms of scale invariance. It may also be very interesting for prediction purposes.

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Section: Log-periodic Antennasmentioning

confidence: 99%

Discrete-scale invariance and complex dimensions

1998

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“…Here again, it is clear that the VSWR values increase and exceed 2.0 beyond 375 MHz. The difference between Figure 3 and the dashed-line profile in Figure 4 could be attributed to the limitations and approximations associated with the open-source 4NEC2 as mentioned by Baker & Reuss (1990). However, we continued the simulation further and found that the high values of VSWR above 400 MHz got reduced below 2.5, when the high-frequency cutoff was slightly increased from 555.6 MHz (conventional design value) to 614.8 MHz.…”

Section: Fine-tuning the Impedancementioning

confidence: 76%

Solar Radio Spectro-polarimeter (50–500 MHz). I. Design, Development, and Characterization of a Cross-polarized, Log-periodic Dipole Antenna

Kumari,

Gireesh,

Kathiravan

et al. 2023

ApJ

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The Zeeman effect has been routinely used to image and quantify the solar photospheric magnetic field (B). Such a direct measuring technique is not yet available for the corona (Lin et al. 2004). Since almost all transient nonthermal radio emissions from the corona are either partially or fully circularly polarized, observing their polarization signatures over broad frequency ranges would be of help to estimate B as a function of heliocentric height. This article aims to describe the design and development of a Cross-polarized Log-Periodic Dipole Antenna (CLPDA), an integral part of a radio spectro-polarimeter, which works in the 50–500 MHz frequency-range and to explain the tests that were carried out to characterize it. The above frequency range corresponds to a heliocentric height range ≈1.03 < r < 2.5 R ⊙ (R ⊙ = photospheric radius), wherein the numerous coronal nonthermal transients associated with space-weather effects are observed to originate. The CLPDA is used to determine the strength and sense of polarization of the received radio signal. The uncertainty involved in the determination depends on the polarization-isolation (PI) between the two orthogonal components of a CLPDA. Some of the recent advancements made in the antenna design concepts at high frequencies (∼GHz) were adopted to reduce the PI at low frequencies (∼MHz). Throughout the above frequency range, the CLPDA has a gain, return loss, and PI of ≈6.6 dBi, ≲−10 dB, and ≲−27 dB, respectively. The average PI of the CLPDA varies from −30 to −24 dB over an azimuthal angle range 0° to ±45° within which the observations are performed regularly.

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“…Geometric simplicity of the LP dipole arrays leads to an important advantage in terms of numerical modeling, which facilitates the investigations and simulations prior to their hardware realizations. Numerous reports introducing new analysis techniques for the LP dipole arrays [ Jones and Mayes , 1969; Wolter , 1970; Paul and Gupta , 1981], investigating their operational properties [ Kyle , 1970; Gong and Balmain , 1986; Hilbert et al , 1989; Baker and Reuss , 1990; Hassan et al , 1991], and developing novel configurations for improved performance [ Oakes and Balmain , 1973; Tranquilla and Balmain , 1983; Wakabayashi et al , 1999; Excell et al , 1999] have appeared in the literature. The same degree of success has not been obtained in the study of other LP structures with more complicated geometries, resulting in relatively fewer reports of detailed analysis [ Bell et al , 1960; Liang and Lo , 1968; Lee and Mei , 1970; Hall , 1986; Smith and Mayes , 1991] based on measurements and approximate numerical techniques.…”

Section: Introductionmentioning

confidence: 99%

Nonplanar trapezoidal tooth log‐periodic antennas: Design and electromagnetic modeling

Ergül

Gürel

2005

Radio Science

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[1] Nonplanar trapezoidal tooth log-periodic (LP) antennas are investigated by combining the wisdom of theoretical design procedures with the power of accurate numerical simulation environments. Once the theoretical design is completed, electromagnetic simulations employing accurate integral equation solvers are utilized to test and correct the original design. A two-element array of trapezoidal tooth LP antennas is designed. The array features beam-steering ability as a novelty, in addition to frequency independence and higher directivity. Beam steering is achieved by optimizing the excitation coefficients of the two LP antennas.Citation: Ergül, Ö ., and L. Gürel (2005), Nonplanar trapezoidal tooth log-periodic antennas: Design and electromagnetic modeling, Radio Sci., 40, RS5010,

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An investigation of the design of a log-periodic dipole array with low side-lobe levels for broadcast applications

Cited by 7 publications

References 1 publication

Discrete-scale invariance and complex dimensions

Discrete-scale invariance and complex dimensions

Solar Radio Spectro-polarimeter (50–500 MHz). I. Design, Development, and Characterization of a Cross-polarized, Log-periodic Dipole Antenna

Nonplanar trapezoidal tooth log‐periodic antennas: Design and electromagnetic modeling

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