Planar Log-periodic Dipole Research Articles

Complete Design Procedure of a Size Constrained Printed Planar Log-periodic Dipole Antenna

Complete Design Procedure of a Size Constrained Printed Planar Log-periodic Dipole Antenna

Reconfigurable log‐periodic dipole array on textile

A microwave planar log-periodic dipole array (LPDA) antenna embroidered on textiles is presented for the first time. This antenna gives a 3.33:1 impedance bandwidth with 5 dBi average gain across the 0.9–3GHz band. This multi-layer textile antenna employs a new denim stack-up for repeatable measurements. The presented LPDA is tested under conformal conditions, with a demonstrated ability of frequency-dependent beam-steering through physical manipulation. Further, the antenna is considered for body-worn applications due to its conformal and low profile. A 2cm thick ground beef slab was used to emulate the human tissue for measurements. Overall, the presented LPDA brings forward new opportunities for several long-distance wideband and wearable applications.

Gain-Enhanced Planar Log-Periodic Dipole Array Antenna Using Nonresonant Metamaterial

In this communication, a novel nonresonant metamaterial (MTM) structure is proposed to enhance the gain of the clamped-mode planar log-periodic dipole array (CMPLPDA) antenna fed by substrate integrated waveguide. The proposed MTM structures composed of a series of metallic semiring patches are printed on both sides of the antenna substrate, featuring low loss, broadband, and easy integration. Different arrangements of the nonresonant MTM with respect to the dipoles of the CMPLPDA antenna are investigated and compared. The proposed gain-enhanced method based on the nonresonant MTM has been studied through both numerical simulations and experiments. Compared to the original CMPLPDA antenna without any MTM inclusions, the proposed CMPLPDA antenna fully loaded with nonresonant MTM inclusions exhibits a gain enhancement of at least 1.6 dB (up to 4 dB at 27 GHz) within the operating band of 26–40 GHz in the simulations, which is also validated by the experiments.

Gain Characteristic Maintained, Miniaturized LPDA Antenna Using Partially Applied Folded Planar Helix Dipoles

The miniaturization of a compact planar log-periodic dipole array (LPDA) antenna usually comes with a side effect of the gain deterioration phenomenon. To address this issue, a folded planar helix (FPH) dipole is designed as a miniaturized radiating element to replace parts of a conventional LPDA antenna composed of $\lambda /2$ dipoles in this paper. The FPH dipole has a radiation resistance and efficiency close to those of a $\lambda /2$ dipole with 39% reduced size and shows a higher radiation quality factor. The LPDA antenna with the longest $\lambda /2$ dipole replaced by the FPH element and the LPDA antenna with the longest and third-long $\lambda /2$ dipoles replaced by the FPH elements are examined. A conventional LPDA antenna can be miniaturized while avoiding gain degradation in the operation band of 400–800 MHz. The lowest impedance matched frequency and the frequency where the directional beam starts to appear are about the same for the proposed miniaturized LPDA antenna. Moreover, the front–back ratio can be improved by the proposed method. The prototype of the two-FPH-element applied LPDA antenna is built, and the design concept is verified experimentally. A size reduction of 39% and an average gain deterioration of −0.2 dB are achieved by the prototype in comparison with a conventional LPDA antenna. The proposed antenna can be utilized in the mobile radio wave direction-finding system.

Broadband Planar Log-Periodic Dipole Array Antenna Based RF-Energy Harvesting System

ABSTRACT In this paper, a low-cost planar log periodic dipole array antenna has been described using triangular dipole elements for broadband RF energy harvesting applications. The antenna measured bandwidth for VSWR ≤ 2 is from 570 to 2750 MHz (1:4.8), which covers all the cellular bands. The radiation pattern is uniform over the entire frequency range. The measured gain is 7.2 dBi with less than ±0.5 dB variation over the entire bandwidth. A Schottky diode-based voltage doubler rectifier is used to convert RF energy to DC voltage. A broadband impedance matching network using an exponentially tapered microstrip line between log periodic antenna and rectifier has been designed. At a distance of 25 m from the cell tower, a voltage of 1.7 V was obtained using the developed broadband RF energy harvesting system across a load of 4.7 kΩ. A voltage of 3 V was obtained across the same load while initiating a call from a cell phone.

Lens Antenna for Wide Angle Beam Scanning at 79 GHz for Automotive Short Range Radar Applications

This communication presents the design and experimental verification of a substrate integrated waveguide fed lens antenna for 79 GHz automotive radar applications. The proposed integrated lens antenna consists of a six layer cylindrical Luneburg lens illuminated by 17 source elements of substrate integrated waveguide fed by a planar log periodic dipole antenna array. The Luneburg lens is developed by using a unique foam material AirexR82 ( $\varepsilon _{r} = 1.12$ ), which is drilled and pressed to achieve the different dielectric constant needed to follow the index law inside the lens. The return loss and the radiation characteristics of the proposed integrated lens antenna are investigated and validated by measurements. A good agreement between the measured and simulated results is observed. The measured results confirm the beam scanning capability of the proposed integrated lens antenna for a wide scan angle of ±85° in azimuth plane having a maximum antenna gain of 15 dBi at 82.5 GHz and gain drop of less than 2.75 dB for the edge feeds. The estimated radiation efficiency of the antenna is found to be 67% at 82.5 GHz.

Compact log‐periodic dipole array antenna with bandwidth‐enhancement techniques for the low frequency band

A compact planar log-periodic dipole array (LPDA) antenna operating from 0.55 to 9GHz with high measured gain is proposed to be implemented in a reverberation chamber as a source antenna. To minimise the total size of the LPDA antenna, variants of top-loading techniques are utilised, and a much smaller spacing factor is opted to specify the spacing between the elements. However, miniaturisation of the LPDA antenna limits the antenna's wideband characteristics over the desired range of frequencies. Hence, a feedline meander and a trapezoidal stub are incorporated into the design as impedance matching techniques to effectively enhance the bandwidth performance especially for the lower band of the antenna's operating frequency range. The LPDA antenna exhibits radiation patterns with and without a radome having the measured gain ranging from 2.48 to 7.89 dBi and from −1.20 to 7.94 dBi, respectively.

항공기 탑재용 경량화 지지 구조를 갖는 평면 LPDA 안테나 설계

본 논문에서는 항공기 탑재용 경량화 지지 구조를 갖는 평면 LPDA(Log-Periodic Dipole Array) 안테나를 제안한다. 제안된 안테나는 항공기 탑재에 적합하도록 가볍고, 구조적 진동에 견딜 수 있는 평면형 골격 지지 구조를 적용하여 설계하였다. 평면형 골격 지지 구조의 재질은 강도와 온도 특성이 우수한 Peek(Polyether ether ketone)를 사용하였으며, 제안된 안테나는 지지 구조 양면에 LPDA 안테나 방사소자를 결합하여 제작되었다. 지지 구조 유전체로 인하여 변화된 입력 임피던스는 일부 방사소자 간격과 길이를 조절하여 매칭시켰다. 설계된 평면 LPDA 안테나의 10-dB 반사손실 대역폭은 시뮬레이션 및 측정 결과, 각각 0.4~3.1 GHz(7.3:1), 0.41~3.5 GHz(8.2:1)로 광대역이었다. 평균 이득은 0.5~3 GHz 대역내에서 시뮬레이션은 평균 6.77 dBi, 측정은 6.55 dBi이었다. 따라서 설계된 안테나는 가볍고 견고한 구조와 광대역 지향성 방사특성을 가져 항공기 탑재 용도로 적합함을 확인하였다. This paper proposes a planar Log-Periodic Dipole Array(LPDA) antenna with light-weight supporting structure for installing on an aircraft. The proposed antenna is designed by applying a planar skeleton supporting structure that has light-weight for an aircraft and is capable of withstanding structural vibration. The material of the planar skeleton supporting structure is a Polyether ether ketone(Peek) which has excellent characteristics on strength and temperature. The proposed antenna is fabricated by attaching the radiating elements of the LPDA on both sides of the supporting structure. The changed input impedance due to the dielectric material of the supporting structure was compensated for by controlling the distance and length of several radiating elements. The 10-dB return loss bandwidths of the designed planar LPDA antenna with light-weight supporting structure are obtained as 0.4~3.1 GHz(7.3:1) in the simulation and 0.41~3.5 GHz(8.2:1) in the measurement. The average gains in 0.5~3 GHz band are 6.77 dBi in the simulation and 6.55 dBi in the measurement. Therefore, we confirm that the designed antenna is appropriate to be installed on an aircraft due to its light-weight structure and wideband directional radiation characteristics.

Ultra‐wideband planar LPDA antenna with mode converter balun

A new balun used for feeding a planar log-periodic dipole array antenna (PLPDA) is proposed. This balun, which is based on mode conversion, converts gradually the transmission mode from quasi- TEM (coaxial cable) to full TEM (balanced line), with an accessible excitation current property (ECP), which is not achievable in classical feeding techniques (infinite or self balun). To validate this approach, an ultra-wideband (UWB) PLPDA antenna was designed with these balun structures for operating in the L and S bands (1-4 GHz) and the results were compared in terms of reflection coefficient and radiation pattern. A PLPDA antenna with a mode converter balun was fabricated. Results show that the proposed balun is a low length (10 mm) frequency-independent (4.5 GHz based on |S11|<-10 dB) device useful for feeding the UWB PLPDA antenna. Moreover, antenna's ECP can be modified, which is necessary for phase centre variation compensation.

The Design and Optimization of Planar LPDAs

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.

A microwave printed planar log-periodic dipole array antenna

A microwave printed planar log-periodic dipole array (LPDA) antenna analysis and design procedure is presented together with the description of a planar feeding technique. The effects of the dielectric substrate on the antenna design are also discussed and taken into account. A numerical technique using the finite element method is employed to obtain the characteristic impedance and effective dielectric constant of the transmission lines involved, i.e., an unbalanced stripline and a balanced line having only two parallel strips. A 4-8 GHz printed LPDA antenna was manufactured and tested, showing very good radiation pattern and voltage standing-wave ratio (VSWR) values over the entire frequency range.