• Journal of electromagnetic engineering and science
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• v.14 no.2
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• pp.54-60
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• 2014

A systematic design for asymmetric coupled-section Marchand baluns is presented. Asymmetrically coupled transmission lines in multilayer configuration are exploited for constructing Marchand baluns. Design equations for characteristic impedance and electrical length of asymmetrical coupled transmission lines are derived for establishing a systematic design procedure. Novel Marchand balun based on these design equations is composed of two identical asymmetrical coupled transmission lines. However, contrary to the general conventional design approach where ranges for characteristic impedances of coupled lines are ambiguously capitalized, values for characteristic impedance and length are explicitly expressed. Our approach is fundamentally different from the design method using coupling coefficients where solution for coupling coefficient is inherently restricted. To verify the proposed method, one design example is performed for wideband Marchand balun in multilayer configuration, and is fabricated for verifying the design procedure proposed. Maintaining the return loss more than 10 dB, the bandwidth is measured from 0.43 to 1.0 GHz, where $S_{21}$ and $S_{31}$ show better than -4 dB. The measured phase and amplitude imbalances illustrate 0.5 dB and ${\pm}5^{\circ}$, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.2 s.117
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• pp.111-117
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• 2007

In this paper, a new marchand balun using broadside-coupled coplanar waveguide(CPW) on flexible printed circuit (FPC) is proposed. The proposed balun is designed based on the coupled line theory. The fabricated balun shows compact size and improved performance compared to the conventional microstrip line marchand balun. Measured amplitude and phase imbalance between the two balanced output ports are within 0.2 dB and $1^{\circ}$ respectively in a wide frequency range($1.63{\sim}3.44$ GHz). The proposed balun is expected to be used between various antennas and RF front-ends as a functional interconnection.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.5 no.2 s.10
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• pp.55-60
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• 2006

In this paper, a broadband double balanced mixer is presented using a wideband Marchand balun implementation by vertical coupler. Frequency is selected as $1.0{\sim}3.7GHz$ for RF, $1.14{\sim}3.84GHz$ for LO, and 140 MHz for IF signals. When LO signal with 7 dBm at 2.64 GHz is injected, a conversion loss of 7.5 dB and RF to LO isolation of -45 dB are obtained. Also, an average conversion loss of 9 dB and RF to LO isolation of -25 dB are obtained for frequency band of $1.0{\sim}3.7GHz$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.10
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• pp.1166-1174
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• 2008

In this paper, design of a $2{\sim}18$ GHz wideband cavity-backed spiral antenna is investigated. Firstly, an arm pattern and a backing cavity of a cavity-backed spiral antenna are designed based on the design theory of an Archimedean spiral antenna as well as by using CST's MWS. VSWR, axial ratio, and HPBW(Half Power Beam Width) characteristics are considered in the simulation. Secondly, a Marchand coaxial balun is designed to meet the required VSWR within the frequency band of operation. Finally, the validity of these approaches is verified by comparing the simulated results with measured ones.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.12
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• pp.1350-1359
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• 2008

This paper presents a wideband doubly balanced resistive mixer fabricated using $0.5{\mu}m$ GaAs p-HEMT process. Three baluns are employed in the mixer. LO and RF baluns operating over an 8 to 20 GHz range were implemented with Marchand baluns. In order to reduce chip size, the Marchand baluns were realized by the meandering multicoupled line and inductor lines were inserted to compensate for the meandering effect. IF balun was implemented through a DC-coupled differential amplifier. The size of IF balun is $0.3{\times}0.5\;mm^2$ and the measured amplitude and phase unbalances were less than 1 dB and $5^{\circ}$, respectively from DC to 7 GHz. The mixer is $1.7{\times}1.8\;mm^2$ in size, has a conversion loss of 5 to 11 dB, and an output third order intercept(OIP3) of +10 to +15 dBm at 16 dBm LO power for the operating bandwidth.