The Analysis of LPDA Using MOM and Transmission Matrix

Currently, the needs of communication system with a wide bandwidth is large enough. One antenna that can be used to realize communication with a wide bandwidth is log periodic antenna. To observe the effect of element length, the distance between elements, and the width of dipole elements used in log periodic antenna then do research to design and realize the antenna log periodic dipole array (LPDA) and log periodic dipole array fractal Koch (LPDAFK) at frequency of 287-324 MHz. The results of the implementation of LPDA and LPDAFK antenna give different results with simulations. On the measurement of LPDA and LPDAFK antennas, antenna operating frequency shifted to a higher frequency. LPDA antenna is working on frequency 295-310 MHz and 360-385 MHz, while the working frequency of the antenna fabrication LPDAFK are 292-304 MHz, 346-354 MHz and 404-414 MHz.

Design and analysis of a super wideband (0.09[formula omitted]30.14 THz) graphene based log periodic dipole array antenna for terahertz applications

In this paper, the design and simulation of a compact printed log-periodic dipole array (PLPDA) antenna operating between 3.4 – 9.5 GHz for VSWR less than 2 is presented. Performance improvement of the antenna is achieved through the use of dipole trimming and parasitic elements. Dipole trimming has resulted in an improved impedance bandwidth while parasitic elements has led to a better gain performance in comparison to the conventional PLPDA. The proposed 12-element low profile PLPDA antenna exhibits high gain of 7.2 – 10.1 dB within the wide operational bandwidth, and a stable directional radiation pattern. The two easy-to-implement performance improvement techniques used in this research has optimized the PLPDA to outperform the conventional PLPDA both in terms of effective bandwidth and gain.

In this paper, it is attempted to approach a fast efficient algorithm for solving the famous Hallen's and Pocklington's integral equations, regarding the current distribution on a finite-length linear thin wire antenna. Here, the conventional moment method in conjunction with wavelet basis functions was used to obtain the current distribution of the antenna. The aim of this work is first to introduce the application of wavelet in electromagnetic scattering, secondly a comparison of the two method of analysis the thin wire antenna. By using the wavelet expansion, wavelets as basis and testing functions, a sparse matrix is generated from the previous moment method dense matrix. A sparsely filled matrix is easier to store and invert. The result extracted from Pocklington's integral equation gives better convergence at the feeding point, though it takes more time to be computed because of the complexity in Pocklington's equation. Results are compared to the previous work done and published, excellent results are obtained.

In order to develop medical antenna at sub-terahertz (THz) band, we propose two kinds of novel designs of log-periodic dipole array (LPDA) antenna for enhanced bandwidth and high gain. Instead of typical rectangular dipole form, one is designed with Taeguk dipole for enhanced bandwidth and the other employs circular dipole shape for high gain, The proposed antennas operate at sub-THz band. Taeguk LPDA antenna works over 60 – 100 GHz frequency range. Circular LPDA antenna achieves maximum gain of nearly 10 dBi at 85 GHz.

The input impedance, gain and directivity of a log-periodic dipole antenna array is analyzed by using moment method and microwave network theory. Based on the results, the antenna array optimal excitation for any desired wave beam direction is analyzed in detail. And the results obtained can be instructional on rational constellation of LPDA array and design of over-the-horizon (OTH) communication system.

Several of the integral equations in everyday use for electromagnetic computations are "not well-posed" (e.g. they are ill-posed). In most other fields, solutions occur, but with arbitrarily large errors that cause serious practical problems. On the other hand, the specific ill-posed equations used in electromagnetics seem to work just fine in practice. G.C. Hsiao and R.E. Kleinman (see IEEE Trans. Antennas and Propag., vol.45, no.3, p.316-28, 1997) considered the ill-posed problem of the electric field integral equation (EFIE). It has been suggested that Pocklington's integral equation is even less well behaved. Our approach is two fold. We re-examine a paper (Canning, F.X. and Scholl, J.F., IEEE Trans. Antennas and Propag., vol.44, no.9, p.1239-46, 1996) which shows how wavelets can be used to improve the condition number (or stability) of the EFIE. We show how these results are equivalent to the results of Hsiao and Kleinman. These wavelet results provide a particularly clear physical picture of what is happening. The stability of the EFIE for its intended purpose becomes clear, in spite of its ill-posed nature. Second, we extend the wavelet related results of Canning and Scholl to Pocklington's integral equation, and explicate its stability properties.

A signiflcant space reduction of a Planar Log-Periodic Dipole Array (LPDA) is achieved in this work. This reduction was performed by utilizing the flrst order iteration meander shape dipole in the design of a planar LPDA. The minimization procedure is illustrated in this work by presenting two designs for a Euclidean LPDA with linear dipoles and a meander LPDA operating over the entire S frequency band. Both designs are compared through the main common characteristics of an antenna: return loss response, radiation pattern and the maximum gain. The agreement between the results of both designs was very good and the properties of the meander LPDA were identical to those of the Euclidean LPDA.

16 elements of ultra-wideband millimetre-wave printed log-periodic dipole array antenna (LPDAA) which fed by the 4-by-4 Wilkinson power distribution network is designed and fabricated for far distance chipless RFID system application. The LPDAAs are design on single side of the Taconic TLX-8 (□ r = 2.55) with 0.5 mm thickness and the feeding network is design on the same material but with 0.13 mm thickness. The antenna is designed to operate in 20–30 GHz. The total array dimension including its power distribution network is 80 × 78 × 60 mm. Radiation pattern is obtained throughout the measured bandwidth. The measured gain of the array is average at 25 dBi over the frequency range of 20–30 GHz and the cross-polarization ratio is less than −20 dB. The printable structure, low return loss, wide bandwidth and high gain of the proposed array suggest it as a suitable antenna for many applications in mm-wave range including chipless RFID systems.

A novel design of multiple input–multiple output (MIMO) antenna based on the log-periodic dipole array (LPDA) for the mobile handsets is presented. The antenna operates in a wide frequency range of 1.86–3.84 GHz compatible with GSM, LTE, WLAN, and WiMAX. The MIMO design consists of two symmetrical and orthogonal radiating elements and a neutralization line (NL). The radiating element comprises a LPDA having a series of printed dipoles connected together with a microstrip line. Triangular and rectangular cuts on ground plane are carried out in accordance with the LPDAs so as to increase the impedance bandwidth and isolation. The antenna elements are linked with the NL to further enhance the isolation between the radiating elements. The performance of the MIMO antenna is analyzed in terms of S-parameters, radiation pattern, gain, total efficiency, envelope correlation coefficient, mean effective gain, multiplexing efficiency; and then it is verified through the measurements. The results demonstrate that the proposed MIMO antenna has good characteristics of wideband, gain, radiation pattern, isolation, and diversity.

A new resonance point optimization (RPO) is applied to reduce the log-periodic dipole array (LPDA) antenna's axial size. The resonance points are redistributed under the premise of the unchanged impedance bandwidth. And the required radiating elements number is reduced. In comparison with the classic LPDA, axial size reduction rates of 18% and 28% are achieved by two proposed RPO LPDAs with a working frequency band of 1-10 GHz. They consist of 19 and 15 elements respectively. An obvious size reduction rate of 44% in the axial direction is obtained through the RPO method at 2–20 GHz. The RPO design technique provides a reference to miniaturize the LPDA axially.

In this communication, several parasitic dipole elements served as director cell are added to the shorter end of the printed Log-periodic dipole array (PLPDA) antenna for the gain enhancement. This novel antenna is based on the combination of the PLPDA antenna and the quasi-Yagi antenna techniques, so called printed Log-Yagi dipole array antenna (PLYDA). The number and the distribution of the director cell are discussed and optimized. A prototype PLYDA antenna fed by half mode substrate integrated waveguide (HMSIW) is manufactured, as well as a HMSIW PLPDA antenna for comparison. The return loss and far-field radiation patterns were measured and presented in this work. The proposed PLYDA antenna exhibits gain enhancement of 0.2-2 dB in comparison with the equal size PLPDA antenna over the operating frequency range 21-40 GHz. The simulated and measured results are in good agreement, and the gain enhancement using the director cell is verified.

It is well-known that the conventional log-periodic dipole array (LPDA) has an impulse response with high levels of ringing compared to other antennas, such as ridged horns or Vivaldi antennas, with comparable frequency domain bandwidth. The ridged horn and Vivaldi antennas are known to have transfer functions that are minimum phase if a suitable spatial origin is chosen. In this paper we first show that the LPDA does not satisfy the minimum phase property, and then decompose the LPDA transfer function into the product of a minimum phase function and an all-pass function. The impulse response corresponding to the minimum phase function has a well defined main pulse and greatly reduced ringing. The all-pass function accounts for virtually all of the long term ringing, and is directly related to the number of transposed transmission line sections joining the elements. The results demonstrate that the LPDA cannot be systematically equalized over an unlimited bandwidth using a passive network.

There is a growing interest in mm-wave antennas and devices for high data transmission to support the future 5G communication. In this work, we have designed a low profile, high gain, broadband four elements printed log periodic dipole array (PLPDA) working over the range of (24-39) Ghz. In the first part of the design, a PLPDA is designed, which achieved around 10.5 dB gain, 49.6% impedance bandwidth. Later some horn corrugation is cascaded to the PLPDA which enhanced the overall gain up to 13 dB, while 52% impedance bandwidth is obtained. All results are validated using two different numerical packages.

A 10-element, size-reduced, circularly polarized log periodic dipole array antenna (CPLPDA) is presented by decreasing the length of the antenna elements in half using arc-shaped, top-loading structures. The simulated −10-dB impedance bandwidth is 106.5%, and the 3-dB axial ratio bandwidth is 110.4% Both bandwidths are matched well. The maximum realized gain in the direction of the shortest dipole is 7.1 dBic. Compared to a λ/2-element CPLPDA, the miniaturized CPLPDA has 75% volume reduction.