Table 2 Summary of S21 properties for various design steps of the proposed metamaterial unit cell.

From: Inductively tuned modified split ring resonator based quad band epsilon negative (ENG) with near zero index (NZI) metamaterial for multiband antenna performance enhancement

Steps

Resonance frequency (GHz)

Amplitude(dB)

Covering Band

Design 1

4.9, 11.15

 − 28.9, − 26.2

C, X bands

Design 2

5.95, 11.3, 13.8, 17.5

 − 33.5, − 25.3, − 13, − 9.7

C, X, Ku bands

Design 3

5.65, 7.2, 11.4, 13.8, 17.4

 − 29, − 24.7, − 25.5, − 12, − 9.4

C, X, Ku bands

Design 4

5.65, 7.14, 11.4, 13.8, 17.4

 − 29, − 24.4, − 25.4, − 11.7, − 9.4

C, X, Ku bands

Design 5

5.5, 6.2, 11.2, 14.4, 17.5

 − 22.5, − 30.1, − 22.9, − 13.9, − 8.4

C, X, Ku bands

Proposed

2.38, 4.24, 5.98, 9.55, 12.1, 14.34

 − 19.7, − 26.0, − 21.8, − 26.1, − 12.0, − 15.7

S, C, X, Ku bands