Design of a Printed Metamaterial-Inspired Electrically Small Huygens Source Antenna for Cognitive Radio Applications

Metamaterial-inspired electric-and magnetic-based near-field resonant parasitic (NFRP) elements are electrically coupled to a coaxial-fed printed monopole to realize an electrically small, ka = 0.49 (lambda(0)/9.41 x lambda(0)/14.11 x lambda(0)/104.18) Huygens source antenna that operates at the GSM1800 frequency. The electric NFRP element is a meander patch; the magnetic element is a Capacitively Loaded Loop (CLL). The individual electric-and magnetic-based antennas were studied numerically to ensure they had overlapping frequency behavior near the GSM frequency 1.8 GHz; high radiation efficiency; and very good matching to their 50 Omega sources. They were combined together and retuned to create a three metal - two dielectric layer Huygens source antenna. A 20 nH inductor was inserted between the driven monopole and the SMA connector in order to enhance the input impedance matching. A prototype of this antenna was fabricated and experimentally characterized. The measurements confirmed the Huygens source nature of the prototype antenna.