dB Branch Line Coupler Research Articles

High gain and circularly polarized beam-switching 8 × 8 Vivaldi antenna array for X-band application

AbstractAn 8 × 8 butler Vivaldi beam-steering antenna array is introduced for X-band application. Circularly polarized array is made of eight Vivaldi elements with 1×8 platform and an 8×8 beam feeding network. Vivaldi radiating element is used in array form to enhance impedance bandwidth and overall efficiency such as gain. Using microwave passive components, for instance, 3 dB branch line couplers and crossover help to have orthogonal modes for feeding each of the elements, hence circular polarization property is achieved. Extracted results show that the array has an impedance bandwidth over 7–12.7 GHz (~58%) for VSWR≤2 and an axial-ratio bandwidth of 3.15 GHz that is between 8.15 and 11.3 GHz (~33%). The peak gain of antenna array is 18 dBi at 10 GHz. The proposed beam-steering antenna with compact size and good operation is capable to cover an angle range from −42 to 55 degree in whole operation frequency.

A compact UWB antenna with dynamically switchable band-notched characteristic using broadband rectenna and DC-DC booster

AbstractIn this article, a dynamically switchable ultra-wideband (UWB) planar monopole antenna employing defected ground structure (DGS) with a folded stepped impedance resonator (SIR) that can operate as either a UWB mode or the single band-notched mode is introduced. The UWB monopole antenna contains a novel whirligig-shaped radiating patch and a chambered conductor as a partial ground plane. The switchable UWB antenna uses one PIN diode as switching elements in the DGS-SIR structure without any biasing network. When the state of diode is OFF, the planar monopole antenna changes to the UWB mode, and when the diode is turned ON, a frequency notch is created at 5–6 GHz. The state of diode is set to the “ON” state dynamically in the presence of a 5–6 GHz RF signal that is detected by using a wireless power management unit (PMU) that contains a broadband rectenna and a DC-DC passive booster. The rectenna consists of a novel cypress-shaped monopole antenna as a signal receiving part and two sub-rectifiers which are connected to a 3 dB branch-line coupler with a grounded isolation port. The antenna switches from UWB to single band-notched when an RF input signal (≥8.5 dBm) in the 5.25 GHz is sensed by the RF PMU with a conversion efficiency of 26% and DC output voltage of 0.36 V, and it fades immediately in real time when the external RF signal is eliminated. In the three-tone signals, the efficiency and input signal improvements are about 10% and −5.5 dBm in the low-power levels, especially, and so develop and enhance the performance of the dynamic reconfigurability.

Miniaturized Wideband CP Antenna Based on Metaresonator and CRLH-TLs for 5G New Radio Applications

This article presents a detailed study on an interesting compact wideband CP antenna using a novel split-ring resonator (SRR) and composite right-/left-handed transmission lines (CRLH-TLs). A novel vertical SRR made by the metallic sheets and PCB substrate is proposed, which achieves substantial size reduction. To obtain wideband CP radiation, a novel 3 dB branch-line coupler using dispersion engineered CRLH-TL is employed as the feeding circuit. The vertical SRR and CRLHTL-based feeding network are analyzed by their own equivalent circuit models. A single-fed CP antenna and a dual-CP (LHCP/RHCP) antenna with a compact size of 0.277 λ0 × 0.277 λ0 ×0.033 λ0 at 3.30 GHz are implemented, respectively. For the dual-CP antenna, both the measured -10 dB |S11| bandwidth and 3 dB axial ratio (AR) bandwidth cover the 5G N78 band (3.30-3.80 GHz, 14.1%) quite well. In addition, the measured peak gain and radiation efficiency are greater than 5.4 dBic and 77% (-1.1 dB), respectively. It shows attractive features including a miniaturized size, low-cost, wide bandwidth, and good CP performance, appearing as good candidates for fifth-generation new radio (5GNR) communication systems.

Compact Microwave Components with Harmonic Suppression Based on Artificial Transmission Lines

In this paper, compact microwave components, including a Wilkinson power divider and a 3 dB branch-line coupler based on artificial transmission lines (ATLs) with harmonic suppression, are presented. A section ATL is consisted of microstrip stepped impedance transmission lines and a microstrip interdigital capacitor. To achieve a compact size, the stepped impedance transmission lines are folded into a right-angled triangle shape. For the ATL, the interdigital capacitor is used to suppress harmonics. By employing two sections of 70.7 Ω ATLs with a right-angled triangle shape to replace conventional transmission lines, the proposed power divider working at 0.9 GHz achieves a size miniaturization with the 58.8% area of a conventional case. In addition, the power divider has good harmonic suppression performance. In the design of a branch-line coupler, two pairs of ATLs with 50 Ω and 35.4 Ω are utilized. For 50 Ω ATLs, the ATLs are designed to a right-angled triangle shape. Meanwhile, to obtain a more compact size, these 35.4 Ω ATLs are modified to an isosceles trapezoid shape. The proposed branch-line coupler operating at 0.9 GHz accounts for merely 33.4% of a coupler adopting conventional microstrip transmission lines. Moreover, the harmonics of a branch-line coupler are suppressed effectively as well. Finally, measured results of the proposed Wilkinson power divider and branch-line coupler display good performance and agree with their simulated results well.

A Low-Cost Compact Planar Dual-Band 3 dB Branch Line Coupler Using an Unbalanced CRLH

In this work, a compact dual-band 3 dB branch line coupler (BLC) is designed with center frequency at 2.45 GHz and 5.08 GHz using an unbalanced composite right/left-handed transmission line. Based on the two-port ABCD parameters, the lumped equivalent circuit of the proposed TL is extracted and optimized to obtain characteristic impedance at 2.45 GHz and 5.08 GHz. The right- and left-handed characteristics of the proposed TL are examined. Incorporating the proposed TL, a dual-band BLC with 0.29λg × 0.3λg size is obtained. The frequency response has magnitude imbalance of 0.8 dB, phase imbalance of 1.8° and 160 MHz bandwidth at 2.45 GHz and magnitude imbalance of 0.81 dB, phase imbalance of 0.006° and 100 MHz bandwidth at 5.08 GHz.

A wideband 3 decibels arbitrary phase difference branch line coupler

AbstractA wideband 3 dB branch line coupler with arbitrary phase difference between output ports is proposed. The wideband properties in both amplitude and phase are achieved by utilizing λ/4 coupled line sections. By designing different even and odd impedance of the coupled line matched in different ports, small phase imbalance can be achieved. For validation, two 3 dB couplers with different phase differences (60° and 120°) were designed and fabricated. They were measured to exhibit wide bandwidths of 40.2% and 44.6%, respectively.

A Full-Duplex Bidirectional Amplifier With Low DC Power Consumption Using Tunnel Diodes

A low-power, switchless, full-duplex bidirectionalamplifier operating in the 915 MHz (ISM band) is proposed.It is composed of two identical reflection amplifiers and one90◦,−3dB Branch Line Coupler (BLC). The reflection ampli-fiers are designed using low DC power consumption tunnel diodesand provide a measured reflection gain of 13 dB with consumedpower of only 178μW for -30 dBm of incident signal power. Thesereflection amplifiers are integrated with a miniaturized BLC toform a bidirectional amplifier that provides 9 dB of measuredtransmission gain and 22 dB of measured return loss.

A miniaturized harmonic suppressed 3 dB branch line coupler using H-shaped microstrip line

A miniaturized harmonic suppressed 3 dB branch line coupler using H-shaped microstrip line

Reconfigurable 3/6 dB Novel Branch Line Coupler

In this paper, a new idea of reconfigurable 3/6 dB branch line coupler is proposed. The proposed coupler is tuned through a simple open and short circuit at the coupler’s branches’ edges. At the short edges case, a 3 dB branch line coupler is obtained. In this case, the coupler’s branches are considered as microstrip transmission lines with 0.3 mm slot width which is etched in each coupler’s branch. At the open edges case, the coupler’s branches are considered as asymmetric coupled microstrip lines. In this case, a 6 dB branch line coupler is obtained. Both CST and IE3D simulators are used to optimize the reconfigurable 3/6 dB branch line coupler dimensions. As a prototypes, two BLCs are designed, analyzed and tested at the “on” and “off” states at 2.5 GHz. The measured S-parameters confirm the proposed concept of the reconfigurable 3/6 dB branch line coupler.

A compact wideband harmonic suppressed 10 dB branch line coupler using cascaded symmetric PI sections

This article presents the size-miniaturized, wide-bandwidth, and harmonic-suppressed 10 dB branch line coupler (BLC) using cascaded symmetric PI sections. The complete design equations are derived to obtain the physical parameters of cascaded PI sections. To validate the proposed design, a 10 dB BLC operating at 0.9 GHz is designed, fabricated, and tested. The reported BLC is having dimensions of 0.175 λg × 0.25 λg and is 76.6% smaller than the conventional coupler. The measured results show that the designed coupler fractional bandwidth is >52% and up to 4th harmonic is suppressed with a level better than 20 dB. Good agreement is found between the theoretical predictions and experimental results. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1610–1613, 2016

Design of dual‐band transmission line with flexible phase shifts and its applications

A novel dual-band transmission line with flexible phase shifts is presented. To realise dual-band operations, the proposed transmission line is constructed by series-connected coupled lines and open-ended stubs. Using this structure, flexible characteristic impedances and electrical lengths can be designed to operate at two frequencies. Moreover, the proposed dual-band transmission line features a wide range of realisable frequency ratios and a flexible structure. For practical applications, a planar dual-band 3 dB branch-line coupler operating at 2/5.2 GHz is designed using the proposed dual-band transmission line. The simulation and measurement results agree very well with the design theory.

Transparent Branch-Line Coupler Using Micro-Metal Mesh Conductive Film

This letter presents the design of a novel transparent 3 dB Branch-Line Coupler (BLC) using a proprietary self-assembling nano-particle technology based Micro-metal Mesh (MM) conductive film. The transparent MM conductive film has a sheet resistance of 0.7 Ω/sq and a visible-light transmission (VBLT) of 75%, resulting in good conductivity and high transparency, respectively. The proposed transparent BLC is mounted on a 2 mm-thick soda-lime glass substrate of dielectric 5.7 and designed to operate at 2.45 GHz. A layer of MM film on the back of the glass serves as a ground. The transparent BLC delivered measured coupling and transmission values of 3.9 and 4.3 dB, respectively. The transparent BLC can be used as a building block for realizing a transparent Butler Matrix (BM) Beam Forming Network (BFN) for Inter/Intra-Vehicle Wireless Communication (IIVWC) in Intelligent Transport System (ITS). Besides being transparent, the proposed BLC has a measured fractional bandwidth of 38.8% and 0.25 mm profile excluding the glass substrate. These advantages greatly enhance the BLC's potential to be used also as a BM building component that can be mounted onto the glass surfaces of buildings for future 5G indoor wireless communications where beam forming is required.

Wideband 3 dB Branch Line Coupler Based on $\lambda/4$ Open Circuited Coupled Lines

This letter introduces a new 3 dB branch line coupler for wideband applications. The wideband matching property of the coupler with four λ/4 open circuited coupled lines is briefly derived. The coupler with a suspended microstrip and microstrip line structures has been simulated with HFSS and fabricated. Measurement results show insertion loss better than 3.6 dB with a power imbalance of 0.5 dB; return loss and isolation characteristics both better than 20 dB over 49% fractional bandwidth.

A Novel Tri-Band Branch-Line Coupler With Three Controllable Operating Frequencies

A novel branch-line coupler with three controllable operating frequencies is presented for tri-band operation. The tri-band operation is achieved by attaching a matching circuit to each port of the conventional branch-line coupler. Closed-form design equations are derived. For verification, a microstrip 3 dB branch-line coupler operating at 0.9/2/2.45 GHz is designed, fabricated and measured. The measured results are in good agreement with the simulated results. When the return loss and isolation are better than 15 dB and 20 dB simultaneously, the measured bandwidths of three operating bands are all almost 40 MHz, while the amplitude imbalance is below 0.8 dB and the phase difference is within .

다이오드를 이용한 가변 감쇠기의 설계 및 제작에 관한 연구

This paper has been fabricated the two different type of variable attenuators using a characteristics of a 3 ㏈ directional coupler and pin diodes. One was not analyzed using the conventional even-odd modes but used simple two-port techniques. The resulting scattering parameters described operation characteristics for the general case where the terminating impedances are equal and unequal. After analyzing resistor role of the π type fixed attenuator, this paper used a pin diode instead of a resistor, The variable attenuators were fabricated using pin diodes for current-controlled attenuation on the coupled ports of a 3 ㏈ branch-line coupler and π type fixed attenuator. The realized variable attenuators have more than 33 ㏈ attenuation ranges at 2.1 ㎓, and the input and output reflection coefficients are less than -13 ㏈. These results could be applied to mobile communication systems. It can be varied gain of the power amplifier according to change a outdoor environmental temperature and improved linearity.

Design of compactL-band 180� phase shifters

The practical design of L-band 180° phase shifters faces two problems. One is associated with the size, and the other with the cost. This paper presents the design of two varieties of 180° phase shifters that minimize the size and manufacturing cost. The first variety is a hybrid-coupled phase shifter whose size is reduced by employing a compact 3 dB branch-line coupler. The second variety is a switched-branch-line phase shifter, which uses only two diodes to perform its function. Both phase shifters employ low-cost UHF diodes in their switching networks. An LC compensation technique is applied to make the diodes good-quality on–off switches in the L-band. Using these compensation methods, low-cost, good-quality compact 180° phase shifters are developed. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 22: 144–148, 1999.

Microstrip Balanced Mixer for S-Band Receiver

The low noise operation over wide bandwidth and with large dynamic range is the main objective of the microwave front-end designers, in which the low noise RF amplifier and the balanced mixer play the important role. This paper describes an integrated balanced mixer developed for use in the receiver for S-band microwave communication system. The design and dévelopment of microstrip circuit elements for the mixer such as the 3dB branch line coupler, impedance transformers to match the transmission line at RF and IF impedances have been described. The mixer noise figure obtained is 8.8 dB (max) over the frequency range of interest. Dynamic range for the mixer is more than 70 dB.

Frequency Downconverters using Microstrip Circuit

In this paper an attempt is made to present the work on microwave frequency downconverter using microstrip circuit, that is being carried out at Himalayan Radio Propagation Unit. The L- and S-band frequency downconverters make use of 3 db branch line couplers and Schottky barrier diodes as mixing elements. The isolation between local oscillator and the signal ports is 14 db (min.). The noise figure and the conversion loss are 9·0 and 8·5 db (max.) respectively in the required bandwidth.