Composite Right/left-handed Transmission Line Unit Cell Research Articles

A VHF Band Small CRLH Antenna Using Double-Sided Meander Lines

In this paper, a miniaturized very-high frequency (VHF) band antenna using both top and bottom meander lines is proposed. To design a compact size antenna in the VHF band, a Composite Right/Left-Handed (CRLH) transmission line is applied to antenna structure; additionally, both top and bottom meander lines were used to achieve a greater inductance. The CRLH transmission line unit cell operates at 88 MHz, and the fabricated antenna is designed by arranging 7-unit cells. The overall size of the proposed antenna is 0.087λ × 0.02λ × 0.0003λ at the lowest operating frequency, and the antenna operates at 84 MHz. The VSWR 3.5:1 reference operating bandwidth of the antenna is 2%. The received power of the proposed CRLH antenna was measured to verify the antenna performance.

Bandwidth and gain enhancement of composite right left handed metamaterial transmission line planar antenna employing a non foster impedance matching circuit board

The paper demonstrates an effective technique to significantly enhance the bandwidth and radiation gain of an otherwise narrowband composite right/left-handed transmission-line (CRLH-TL) antenna using a non-Foster impedance matching circuit (NF-IMC) without affecting the antenna’s stability. This is achieved by using the negative reactance of the NF-IMC to counteract the input capacitance of the antenna. Series capacitance of the CRLH-TL unit-cell is created by etching a dielectric spiral slot inside a rectangular microstrip patch that is grounded through a spiraled microstrip inductance. The overall size of the antenna, including the NF-IMC at its lowest operating frequency is 0.335λ0 × 0.137λ0 × 0.003λ0, where λ0 is the free-space wavelength at 1.4 GHz. The performance of the antenna was verified through actual measurements. The stable bandwidth of the antenna for |S11|≤ − 18 dB is greater than 1 GHz (1.4–2.45 GHz), which is significantly wider than the CRLH-TL antenna without the proposed impedance matching circuit. In addition, with the proposed technique the measured radiation gain and efficiency of the antenna are increased on average by 3.2 dBi and 31.5% over the operating frequency band.

Analogue predistorter based on non‐linear CRLHTL

A low insertion loss (IL) analogue predistorter using non-linear composite right–left-handed transmission line (CRLHTL) is presented. The proposed predistorter consists of two symmetrical CRLHTL unit cells. In the experiment, this predistorter can achieve about 2.2 dB gain expansion and 17° phase shift during 4.4–4.5 GHz with only 4.3 dB IL. A C-band 40 W solid-state power amplifier observes 8.1 dB enhancement in the intermodulation at −6 dB output power backoff when linearised by the proposed predistorter.

분산 CRLH 전송선로 4중 모드 공진기를 이용한 이중-광대역 대역통과 여파기 설계

본 논문은 CRLH (composite right/left handed) 전송선로 구조의 4중 모드 공진기를 이용하여 높은 대역간 격리도를 갖는 이중-광대역 대역통과 여파기를 설계하는 방법을 제안한다. CRLH 전송선로 구조를 해석하여 4중 모드 공진기의 s-패러미터와 공진 주파수를 유도하였다. 유도된 s-패러미터를 이용하여 새로운 구조의 이중-광대역 대역통과 여파기를 설계, 제작하였다. 측정 결과는 2.8-5.52 GHz, 9.68-12.26 GHz의 이중 통과대역에서 각각 1.08 dB, 2.01 dB의 삽입손실을 갖고, 6.34-8.42 GHz의 중간대역에서 38dB의 대역 격리도를 가져 설계 결과와 잘 일치하는 특성을 보여 주었다. This paper presents a dual-wideband bandpass filter (BPF) with high band-to-band isolation and skirt selectivity using distributed composite right/left-handed (CRLH) transmission line (TL) quad-mode resonators (QMRs). The results of the proposed distributed CRLH TL unit cell analysis are used to establish the scattering parameters and the resonance frequencies of the QMR constituting the dual-wideband BPF. A novel dual-wideband bandpass filter is designed and fabricated, using the derived scattering characteristics. The measured results show that the fabricated dual-wideband bandpass filter has an insertion loss of less than 1.08dB in the lower band, and of 2.01dB in the upper band, a bandwidth of 2.8-5.52GHz and 9.68-12.26GHz, and a band-to-band isolation of more than 38dB, from 6.34-8.42GHz.

An Electrically Controlled CRLH-Inspired Circularly Polarized Leaky-Wave Antenna

An electrically controlled beam-scanning circularly polarized leaky-wave antenna is presented by cascading multiple unit cells of a composite right/left-handed transmission line (CRLH-TL) structure. The CRLH-TL unit cell consists of two parts: varactor diodes (two series ones and a shunt one), which enable beam electrically steerable at a fixed frequency, and a subwavelength (0.2 λg × 0.2 λg) square-shaped patch that is perturbed to stimulate circular polarization radiation. Moreover, a single-voltage bias circuit, which allows all the unit cells to be simply controlled by a single uniform bias voltage, is introduced to steer the beam direction. The proposed antenna operates at 2.4 GHz and beam scans from +40° to –17° continuously. The axial ratio remains below 3.5 dB at different bias voltages.

Compact Antenna Using Finger-Connected Interdigital Capacitor-Based Composite Right/Left-Handed Transmission-Line Unit Cell

A compact antenna using a novel finger-connected interdigital capacitor (FC-IDC)-based composite right/left-handed transmission-line (CRLH-TL) unit cell is presented. First, the characteristics of the proposed CRLH-TL are investigated. Compared with the conventional IDC-based CRLH-TL unit cell, the proposed one has a lower $-1\text{st}$ -order resonant mode. Then, an antenna using the proposed CRLH-TL unit cell is designed, fabricated, and measured. By using the conventional IDC-based CRLH-TL unit cell and the microstrip patch, another two antennas are also designed, fabricated, and measured for comparison. The measured results show that the antenna using a CRLH-TL unit cell based on FC-IDC achieves 21.98% and 32.81% reductions in operating frequencies compared with the two antennas with the same size. Additionally, the newly designed antenna can also be implemented easily with printed circuit board technology, which makes it very useful in small communication systems.

Design of dual‐bandpass filter using zeroth‐order resonance and Bragg frequency

This study presents a novel compact dual-bandpass filter using zeroth-order resonance and Bragg frequency of the composite right/left handed transmission line (CRLH-TL) resonator. By taking advantage of the Bragg frequency, two resonance modes are obtained with only one CRLH-TL unit cell. The equivalent circuit for the novel resonator is proposed and analysed. The resonance frequencies are given by using the circuit model and the input impedance is calculated. Dimensions of the resonator can be obtained based on the values of the lumped elements in the equivalent circuit. Compared with the conventional half-wavelength resonator, the size of the presented resonator is only about one-tenth of it. Then, the zeroth-order resonance and Bragg frequency modes are demonstrated using the dispersion curve. A dual-bandpass filter is designed to verify the resonator analysis. The source–load coupling is involved to improve the frequency selectivity of the filter. The fabricated filter is compact with a size of only 0.09 λg × 0.16 λg. The two central frequencies are located at 2.4/3.3 GHz and the filter has a wide upper stopband of over 4 GHz. Moreover, the fabricated filter has five transmission zeros and good frequency selectivity is observed.

MULTIBAND ANTENNA BASED ON LOADING A CPW-FED MONOPOLE WITH ONE CRLH-TL UNIT CELL

A Coplanar Waveguide (CPW)-fed monopole loaded with Composite Right/Left Handed Transmission Line (CRLH-TL) unit cell is presented in this letter. Multiband is achieved due to the nonlinear dispersion relation of the CRLH-TL unit cell. The CRLH-TL unit cell supports a fundamental LH wave (phase advance) at lower frequencies and a RH wave (phase delay) at higher frequencies. By loading CRLH-TL unit cells with a conventional monopole, the resonant frequency of higher order mode can be decreased, and zeroth-order mode or even negative-order mode can be achieved. As a result, the proposed antenna operates at 1.43GHz, 2.58GHz, 3.31GHz and 4.4GHz. Finally the modifled antenna is fabricated and measured; measurements and EM simulations are in a good agreement that conflrms the proposed theory.

A NOVEL VIA LESS RESONANT TYPE ANTENNA BASED ON COMPOSITE RIGHT/LEFT-HANDED TRANSMISSION LINE (CRLH-TL) UNIT CELL WITH DEFECTED GROUND STRUCTURE

In this paper, a novel via-less balanced composite right/left handed transmission line (CRLH-TL) unit cell using defected ground structure (DGS) is presented, and a resonant type antenna based on the proposed CRLH-TL unit cell is designed. Equivalent circuit model is developed to analyze the CRLH-TL unit cell antenna. The resonant frequency is studied, and the resonant frequency tuned by adjusting the dimension of the antenna patch is simulated. The antenna simulated and measured results are presented. The measured central frequency is 5.55GHz. A peak gain of 6.7dBi with an e-ciency of 75.6% is obtained at the central frequency.

DESIGN OF A COMPACT QUAD-BAND HYBRID ANTENNA FOR COMPASS/WIMAX/WLAN APPLICATIONS

A compact quad-band hybrid antenna for Com- pass/WiMAX/WLAN applications is proposed. The hybrid antenna is designed based on the method of combining a composite right/left- handed transmission line (CRLH-TL) unit cell with a meandered monopole and wide multi-band characteristics are achieved by merg- ing some of resonance frequencies of the CRLH-TL unit cell and me- andered monopole together. Coplanar waveguide (CPW) is used as a parallel excitation for both the CRLH-TL unit cell and meandered monopole. A prototype of the proposed hybrid antenna has been con- structed and experimentally studied. The measured results show that four distinct operating bandwidths with 10dB return loss are about 30MHz (1.25{1.28GHz), 290MHz (2.44{2.73GHz), 650MHz (3.17{ 3.82GHz) and 1130MHz (5.03{6.16GHz), covering the Compass B3, 2.5/3.5/5.5GHz WiMAX and 5.2/5.8GHz WLAN bands. Further- more, the antenna has a single-layer planar structure with a small volume of only 31 £ 21 £ 2mm 3 . Acceptable radiation patterns and peak realized gains are obtained over the operating bands.

제어 가능한 전송 영점을 갖는 CRLH 전송 선로

In this paper, a novel CRLH-TL unit cell with controllable transmission zeros was proposed. Proposed composite right/left handed transmission line(CRLH-TL) unit cell is implemented in the form of the metal-insulator-metal(MIM) capacitors, the microstrip stub inductors, and the co-planar waveguide(CPW) inductor. And this proposed CRLH-TL generates two transmission zeros in lower/upper passband by the effort of electromagnetic couplings between each MIM capacitors and microstrip stub inductors. Using this proposed CRLH-TL, broad bandpass filter for UWB system was designed and fabricated. The measured results reveal that the two transmission zeros are observed in lower/upper passband and the overall size of the filter, excluding the feed line is about 8 mm8 mm, less then /4 on electric size.

A 3‐bit phase shifter with high‐power capacity based on composite right/left‐handed transmission line

AbstractA miniaturized 3‐bit phase shifter with high power‐handling capacity is designed based on the use of a single composite right/left‐handed transmission line (CRLH‐TL) unit cell. PIN diodes mounted on the fingers of the CRLH‐TL unit cell are used as switches to control the phase shift of the input signal. Different phase shifts are achieved by using different states of the switches determined by the 3 controlling bits of the phase shifter. The surface current flowing through each of the switches is only a fraction of the total current through the device, so the power handled by each of the PIN diodes is much smaller than the total power through the device. The phase shifter is designed to provide a phase‐shift range from 0° to 157.5° at a step 22.5° and operate in the frequency band from 9 to 10 GHz. Simulation results and measurement results of the prototype agree closely and show that the phase shifter has much higher power‐handling capacities than that of the PIN diode and low insertion losses across the operating frequency band. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1778–1782, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25346

Novel filter using composite right/left-handed transmission line

A novel filter using composite right/left-handed (CRLH) transmission line (TL) unit cells is designed, fabricated, and measured. After properly designing the parameters of the capacitors and the inductors, we have generated a narrow bandpass filter. The simulation results show that the bandpass filter with 4 CRLH TL unit cells has very small loss in the passband and very sharp transitions at the edges of the passband. The performances of the proposed filter are demonstrated by measured results, which are in good agreement with the simulation ones. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2013–2015, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21860

A power divider based on a new kind of composite right/left-handed transmission line (CRLH TL) unit

A new power divider, composed of a novel composite right/left-handed (CRLH) transmission line (TL) unit, is proposed. The properties of the power divider based on four CRLH TL unit cells are investigated theoretically. By adjusting the parameters of the capacitors and the inductors, the power divider shows perfectly symmetric power division at 5.13 GHz, return loss up to −24 dB, with the transmitted power being close to −3.1 dB. The phenomena are demonstrated by simulation results. Being compact in size and low-cost, the proposed power divider is very suitable for microwave and millimeter wave integrated circuits.