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2021-06-24

A Novel Planar Filtering Magic-T

Jun-Mei Yan,

Dr. Jun-Mei Yan

School of Mechanical and Electronic Engineering

Jingdezhen Ceramic Institute

China

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Hai-Ying Zhou,

Dr. Hai-Ying Zhou

School of Mechanical and Electronic Enginerring

Jingdezhen Ceramic Institute

China

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Liangzu Cao

Professor Liangzu Cao

School of Mechanical and Electronic Engineering

Jingdezhen Ceramic University

China

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Progress In Electromagnetics Research Letters, Vol. 98, 121-127, 2021

doi:10.2528/PIERL21041104

Abstract

This paper presents a planar filtering magic-T with a simple structure. It consists of four half-wavelength microstrip resonators with one loaded with a shorted microstrip stub at its central location. The resonator loaded with a shorted microstrip stub has the even-symmetry resonant mode. Other three resonators have the odd-symmetry resonant mode. The planar filtering magic-T has four ports, which all adopt a tapped line structure. Its novelty lies in the simple structure. Compared with previous works in the literature, its inter-resonator coupling zones are apart away and have no influence on each other, which means a simple design. Furthermore, a different-properties coupling is not needed, and its filtering response can be easily extended to the high-order case. The operational mechanism and design method are introduced in details. A planar filtering magic-T with center frequency of 920 MHz was designed and fabricated. The measured results show that, at the center frequency, the return losses (S₁₁/S₄₄) is less than 20/12 dB; an isolation degree of 25 dB (S₄₁) can be observed; the insertion loss of the difference port (S₂₁/S₃₁) and sum port (S₂₄/S₃₄) are 4.5/4.7 dB and 4.3/4.6 dB; the phase unbalance is 8˚/7˚(Σ/Δ). Totally, these results can verify the effectiveness of the proposed novel planar fiiltering magic-T.

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Jun-Mei Yan, Hai-Ying Zhou, and Liangzu Cao, "A Novel Planar Filtering Magic-T," Progress In Electromagnetics Research Letters, Vol. 98, 121-127, 2021.
doi:10.2528/PIERL21041104

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