Table 5.

Comparison of the effects of curvature on the radiation characteristics of different flexible substrates for mictrostrip patch antennas.

Substrate	Versions	Conductive Material	Ground Plane	ϵr	Loss Tangent tanσ	Substrate Dimension (mm)	Substrate Thickness (μm)	Bending Level Curvature (mm)		Band/Frequency Fo (GHz)		Return Loss S1,1 (dB)		Gain (dBi)			Application
Polyimides (PI) [7,14,26,29,57,58]	Kapton 200 HN (2 mil 50 μm)	Silver Nano Particles	AMC	3.5	0.002	45 × 30	50.8	Flat		2.45		−29		NA			ISM
								r1 = 27 mm		2.35		−30
								r2 = 13 mm		2.30		−28
	Kapton 500 HN (5 mil 125 μm)	Silver Nano Particles	CPW Curved shape	3.5	0.0026	70 × 70	110	Convex	Concave	Multiband		Gain dBi Convex		Gain dBi Concave			WLAN
								r1 = 78 mm	r1 = 78 mm	Bands		r1	r2	r1	r2		ISM
								r2 = 59 mm	r2 = 59 mm	(1) 0.87–1.0		−1.2	−1.2	−1.1	−1.1		Bluetooth
								Unbent		(2) 1.4–2.2		0.9	1.0	0.9	0.9		LTE
										(3) 2.5–2.7		2.3	2.5	2.1	2.2		WiMAX
										Unbent		(1) −1.2	(2) 0.6		(3) 2.1
	Kapton 200 HN (2 mil 50 μm)	Silver Nano Particles	NA	3.4	0.002	47 × 33	50.8	Flat		ISM/UWB		S1,1(dB)					ISM UWB
										2.2–14.3		Flat	r1		r2
								r1 = 10 mm		2.5–5.5		2212−23	−24		−22
										4.9–8.6		−37	−29		−27
								r2 = 8 mm		10–14.3		−23	−24		−27
	Kapton 500 HN + parylene–C	Copper	Copper	3.5	0.0008	32 × 18	127	Flat		9 GHz		−35 dB		NA			WLAN
				2.95			10	r = 40 mm				−32.5 dB					UWB
	Kapton 500 HN	PANI + MWCNT	NA	3.48	0.0026	48 × 33	130	Unrumpled		4.2		−17		NA			PCS
						35 × 33 (crump)		Crumpled at r = 5.5 mm		1.9, 5.7		−18,−26					WLAN
	Kapton 200 HN (2 mil 50 μm)	Silver Nano Particles	NA	3.4	0.0020	30 × 33	50.8	Flat		8.8		−23		NA			UWB
								r1 = 9 mm		7.7		−26
								r2 = 7 mm		8.2		−24
Polyethylene Terephthalate (PET) [62,66]	PET Polymer	Copper	Copper	3.0	0.008	59 × 4.75	100	Flat (Switch: OFF)		2.35, 3.61		−15, −12.5		NA			Dual Band
								r = 25 mm (Switch: OFF)		2.34, 3.64		−18, −15
								Flat (Switch: ON)		2.41		−16					Single Band
								r = 25 mm (Switch: ON)		2.44		−21
	Melinex CW 401	Micro-silver particles	NA	3.0	0.002	52 × 82	50	Flat		4.2, 5.3, 6.4, 7.5, 8.8		−28		NA			RFID RCS UWB
								r = 100 mm		4.4, 5.4, 6.5, 7.6, 8.9		−47
								r = 60 mm		4.4, 5.3 6.5, 7.4, 8.8		−49
								r = 30 mm		4.5, 5.6, 6.7, 7.4, 9.6		−50
								r = 16 mm		3.6, 4.3, 6.5, 7.6, 9.0		−50
Polydimethylsiloxane (PDMS) [3,73,148,170]	PDMS Sylgard184	Copper	Copper	2.65	0.02	46.4 × 20	2000	Flat		6.35		−36 dB		NA			Wire-Less
	SU-8			2.9	0.04			Curvature K = 66.91		6.0		−17 dB
	PDMS Sylgard184	Fibre Tissue	Fibre Tissue	2.85	0.02	50 × 40	2000	Flat		7.0	17.5	−26	−30	4.3		4.5	UWB
								r1 = 50 mm		8.0	21.0	−19	−17	3.9		3.7
								r2 = 25 mm		7.8	18.2	−28	−23	3.2		3.3
	PDMS Sylgard184	Copper	NA	2.65	0.02	130 × 80	2000	Flat		381		−15		NA			TETRAPOL (385 MHz)
								r = 230 mm		383		−18
	PDMS	Nickel	NA	2.2	0.013	-	5000	Flat		2.22		−28		NA			ISM Band
		Gold						r1 = 80 mm		2.24		−43
		Copper						r2 = 40 mm		2.39		−34
Polytetraflouroethene (PTFE) [77,78,176]	PTFE	Copper	Copper	2.2	0.0009	25 × 50	127	Flat		3.5	13.3	−21	−19.5	NA			WiMAX X-Band
								r1 =50 mm		3.7	13.4	−16	−17.5
								r2 = 40 mm		3.9	13.4	−15	−18
	PTFE	Conductive Textile	Conductive Textile	2.1	0.002	95 × 90	500	Flat		2.25		−26		NA			ISM Wearable ES
								r1 = 200 mm		2.16		−38
								r2 = 150 mm		2.75		−13
	PTFE	Conductive Textile	Conductive Textile	2.1	0.0002	95 × 90 offset of slot 28.6 and stub 25.0	500	Flat		2.5	BW 0.23	−15		NA			ISM Band
								r1 = 225 mm		2.25	No BW	Below −10
								r2 = 150 mm		2.25	BW 0.05	−11
Rogers PTFE Laminates [222]	RO4003C	Copper	Copper	3.38	0.0027	80 × 60	200	Flat		3.0	3.8	−17	−20	NA			WLAN
								r1 = 100 mm		2.90	3.7	−18	−19				WiMAX
								r2 = 70 mm		2.95	7.7	−17	−16
	RT/duroid 5880	Copper	Copper	2.20	0.0009	39 × 39	50.8	Flat		2.40–2.48 BW		−18		NA			ISM Band
								r1 = 60 mm		2.361–2.534		−17.9
								r2 = 40 mm		2.382–2.552		−17.7
								r3 = 20 mm		2.367–2.543		17.3
	RO3003	Aluminium Silicon Nitride	NA	3.0	0.0010	-	128	Flat		7.24		−23.5		NA			UWB
								r1 = 40 mm		7.23		−18
								r2 = 20 mm		7.25		−18.5
Liquid Crystal Polymers (LCP) [10,81,149]	Rogers ULTRALAM 3850	Silver Nano Particles	Copper	2.9	0.0025	13.2 × 4.2	100	Flat		29		NA		6.4			Wireless Devices
								r1 = 6 mm		28				5
								r2 = 4 mm		28				4.8
	LCP	Copper	Copper	2.9	0.002	26 × 16	50	Flat		6.4	7.4	−22	−20	NA			UWB Wearable applications
								15 degree (min bent)		6.35	7.6	−20	−23
								60 degree (max bent)		6.4	7.8	−21	−20
	LCP	Copper	Copper	2.9	0.002	19 × 50	100	Flat		5.20		−24		NA			ISM
								30 degree (min bent)		5.20		−24					RFID
								60 degree (max bent)		5.25		−25					UWB