A Novel Design of an H-shaped Microstrip Diplexer

Fig. 7
(a) Resonance frequency versus the length of the coupling patch L₉ for different values of width W₄ (b) External coupling coefficient Q versus the width of the coupling patch W₄.

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Fig. 8
(a) Simulation results of the proposed diplexer by using ADS. (b) Simulation results of the fundamental and the first spurious frequencies of the designed diplexer.

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Fig. 9
(a) S-Parameters results and (b) Simulated group delay time of the proposed diplexer by using CST-MWS.

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Fig. 10
Electrical-field distribution at (a) 1.575 GHz and (b) 2.4 GHz.

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Fig. 11
(a) The proposed microstrip diplexer (b) Layout of the defected ground slots.

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Fig. 12
The simulation results of the proposed microstrip diplexer with defected ground structure by using CST-MWS.

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Fig. 13
Simulated group delay time of the proposed diplexer with DGS by using CST-MWS.

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Table I
The values of the LC model components.

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Table II
Comparison between the simulations results obtained with ADS and CST-MWS.

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Table III
Comparison between the simulations results of the proposed diplexer before and after incorporating the cross slots.

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Table IV
Comparison between the proposed diplexer and other works proposed in literature.

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Parameter	Simulation results (ADS)		Simulation results (CST)
Parameter	TX	RX	TX	RX
Frequency GHz	1.557	2.4	1.580	2.38
Bandwidth	96 MHz	166 MHz	132 MHz	182 MHz
Insertion loss [dB]	1.98	2	2	1.9
Return loss [dB]	23	30	17	21

Parameter	Simulation results (Without DGS)		Simulation results (With DGS)
Parameter	TX	RX	TX	RX
Frequency GHz	1.580	2.38	1.214	1.636
Bandwidth	132 MHz	182 MHz	88 MHz	180 MHz
Insertion loss [dB]	2	1.9	2.4	1.7
Return loss [dB]	17	21	19	25
Isolation [dB]	21.5		19.9

	Center frequency f₀ in GHz	\|S₁₂\|/\|S₁₁\| (dB)		-3 dB FBW (%)		Isolation in (dB)	Circuit size (mm²)
	Tx/Rx	Tx	Rx	Tx	Rx	Isolation in (dB)	Circuit size (mm²)
Ref [¹⁸18 Chen, C. F., T. Y. Huang, C. P. Chou, and R. B. Wu, “Microstrip diplexers design with common resonator sections for compact size, but high isolation,” IEEE Trans. Microw. Theory Tech., Vol. 54, 1945-1952, 2006.]	1.5/2	2.7/20	2.8/20	3.4	3.4	40	33.9 × 54.4
Ref [²⁷27 Chinig, A., Zbitou, J., Errkik, A., El Abdellaoui, L., Tajmouati, A., Latrach, M., & Tribak, A. “A novel design of microstrip diplexer using triangular loop resonators.” International Journal of Microwave and Optical Technology, Vol 1, No 10, Jan, 2015.]	2.4/3.2	1.7/30	1.38/30	3.5	4.7	23	16 × 47
Ref [²⁸28 Chinig, A., Errkik, A., Tajmouati, A., Bennis, H., Zbitou, J., & Latrach, M. “The design of new structures of planar diplexers using microstrip resonators.” Handbook of Research on Advanced Trends in Microwave and Communication Engineering, pp. 170-204, September, 2016.]	1.8/2.4	2.17/25	1.7/35	5.5	9.7	22.4	40 × 17
Ref [²⁹29 Chuang, M. L., & Wu, M. T. “Microstrip diplexer design using common T-shaped resonator.” Microwave and Wireless Components Letters, IEEE, Vol 11, No 21, pp. 583-585, October, 2011.]	1.95/2.14	1.22/15	1.12/15	3.1	2.8	30	40 × 70
Proposed circuit without DGS	1.58/2.38	2/17	1.9/21	8.35	7.6	21.5	37 × 21
Proposed circuit with DGS	1.2/1.6	2.4/19	1.7/25	7.3	11.25	20	37 × 21

L1(nH)	L2(nH)	L3(nH)	L4(nH)	L5(nH)
1.95	5.35	1.46	1.9	1.9
L6(nH)	L7(nH)	L8(nH)	L9(nH)	L10(nH)
4	1.9	4.9	0.6	0.6
L11(nH)	L12(nH)	L13(nH)	L14(nH)	L15(nH)
1.2	4.9	3.4	1.9	2.6
L16(nH)	L17(nH)	L18(nH)	L19(nH)
1.9	5.6	1.1	1.95
C1(pF)	C2(pF)	C3(pF)	C4(pF)	C5(pF)
0.42	0.115	0.4	0.3	0.4
C6(pF)	C7(pF)	C8(pF)	C9(pF)	C10(pF)
0.015	0.015	0.015	0.015	0.4
C11(pF)	C12(pF)	C13(pF)	C14(pF)
0.3	0.4	0.44	0.089

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A Novel Design of an H-shaped Microstrip Diplexer

Abstract