A Wideband Circularly Polarized Antenna with Characteristic Mode Analysis

Table 2

Comparisons of the proposed and other CP antennas.

Ref. year	Dimension of patch × height of antenna (λARd)	Impedance matching	Impedance bandwidth	3-dB AR bandwidth	Gain (dBic)
[5] 2014	ϕ0.55 × 0.14	S11 ≤ −14 dB	27% (1.45–1.9 GHz)	16% (1.51–1.77 GHz)	About 7.7–8
[9] 2014	0.24 × 0.24 × 0.13	S11 ≤ −10 dB	42.3% (4.1–6.3 GHz)	16.8% (5.05–5.98 GHz)	Peak gain: 6.7
[10] 2017	About 0.27 × 0.27 × 0.07	S11 ≤ −10 dB	38% (5–7.35 GHz)	28.1% (5.32–7.06 GHz)	Peak gain: 8.4
[11] 2018	0.32 × 0.32 × 0.21	S11 ≤ −10 dB	60.5% (1.5–2.8 GHz)	31% (1.74–2.38 GHz)	6.5 ± 0.4
[12] 2017	0.45 × 0.44 × 0.11	S11 ≤ −10 dB	25% (2.15–2.75 GHz)	25% (2.1–2.7 GHz)	Peak gain: 8.3
[13] 2019	0.67 × 0.45 × 0.21	S11 ≤ −10 dB	31.7% (2.35–3.3 GHz)	15.3% (2.6–3.06 GHz)	6.46–7.64
[14] 2018	0.15 × 0.15 × 0.09	S11 ≤ −10 dB	44.5% (4.64–7.3 GHz)	27.5% (4.55–6 GHz)	Peak gain: 7.2
[15] 2014	0.31 × 0.31 × 0.19	S11 ≤ −10 dB	24% (3.2–4.1 GHz)	16% (3.5–4 GHz)	Peak gain: 9.6
[16] 2015	ϕ0.34 × 0.16	S11 ≤ −10 dB	29.7% (3–4.1 GHz)	21.6% (3.3–4.1 GHz)	Peak gain: 8.6
[19] 2014	0.35 × 0.35 × 0.08	S11 ≤ −10 dB	23.6% (2.09–2.65 GHz)	17.9% (2.18–2.61 GHz)	About 8.5
[20] 2018	1.7 × 1.7 × 0.22	S11 ≤ −10 dB	53.1% (3.9–6.72 GHz)	15.6% (4.73–5.53 GHz)	12.4–13.4
Prop.	ϕ0.45 × 0.18	S11 ≤ −18 dB	40.3% (1.486–2.236 GHz)	31.6% (1.6–2.2 GHz)	8.02–9.76

λ_ARd is the free-space wavelength at the starting frequency of the 3-dB AR bandwidth. λ_ARd is the free-space wavelength at 2.15 GHz. λ_ARd is the free-space wavelength at 4.64 GHz.