Design and Implementation of Single-Layer 4 × 4 and 8 × 8 Butler Matrices for Multibeam Antenna Arrays

Table 3

Comparison of the proposed BMs and previous works.

	This work	[3]	[7]	[8]	[13]	[9]	This work	[20]	[19]	[24]
Matrix order							8 × 8	8 × 8	8 × 8	8 × 8
Process	Single-layer PCB (FR4)	0.18 μm CMOS	Glass-based TF-IPD	Single-layer PCB (Rogers 5880)	Double-layer PCB (FR4)	VIP	Single-layer PCB (FR4)	Multilayer PCB	Single-layer PCB (Rogers 4003C)	PCB-Integrated stripline
Bandwidth (GHz)	2.32-2.52	2.4-2.6	2.4-2.6	2.2-2.6	2.4	1.3-2.32	1.8-2	1.6-2.8	2.4-2.5	2.5-3.5
Input RL (dB)	-15	-20	-13	-10	-10	-10	-15		-13	-20
Transmission coef. (dB)	-7	-11	-10	-8.2	-10	-7.5	-12	-11.6	-12.5	-11
Amplitude imbalance (dB)	0.5	1.5	1.1	1.7	3	1	1.5	1.5	1	0.5
Phase error (deg)	7	4	13	2.1	7	7	12	31	12.5	10

Within the whole BW, worst case. Refers to the center frequency.