volume | PIER Journals

Abstract

A two-port multiple-input multiple-output (MIMO) antenna that pairs a slotted annular-ring radiator with a single front-side parasitic strip is reported for X- and Ku-band service. Three features distinguish the design. A set of eight arc slots elongates the ring-current path by 9.1% and drags the lower band edge down to 8.00 GHz on a board only 0.40λ₀ tall, so the aperture keeps a narrow strip outline suited to edge mounting. The front-side strip works as a three-quarter-wave trap on the shared substrate and lifts worst-case in-band isolation by 8.4 dB with no defected ground and no via. Every element of the accompanying circuit model maps to a named piece of metal, which lets the model track S₂₁ as well as S₁₁, whearea most published models fit the reflection coefficient alone. The radiator occupies 40 × 15 × 0.8 mm³ on Rogers RT/Duroid 5880 (ε_r = 2.2, tanδ = 0.0009). Measurement gives a -10 dB band of 8.00-13.96 GHz, a fractional bandwidth of 54.3%, isolation better than 21.1 dB across the band with a 33.4 dB peak, gain of 4.0-6.5 dBi and radiation efficiency of 77-84%. Diversity metrics stay within useful limits: envelope correlation coefficient below 0.0038, diversity gain above 9.981 dB, mean effective gain between -3.05 and -3.52 dB, channel capacity loss under 0.331 b/s/Hz and ergodic capacity of 13.01-13.28 b/s/Hz. Characteristic mode analysis at 8.85 and 11 GHz identifies modes carried by the ring. A quarter-wave counterpoise argument predicts the lower edge to within 1.11% of measurement, and two independent routes to the ring resonance differ by only 4.14%. The circuit model reproduces the full-wave response with 0.352 dB RMS error on S₁₁ and 0.611 dB on S₂₁, matching the upper band edge to 0.07%.

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Dr. Anbarasu Muthu Manickam

Dr. Loganathan Mohana Sundari

Dr. Thangamani Premakumari

Dr. Idapadi Rajaram Suganya

Dr. Duraipandian Amaravathi

Dr. Johnpeter Jasmine Hephzipah

Dr. Dhanushkodi Siva Sundhara Raja

Dr. Rajesh Kumar Dhandapani