Design of an Electrically Small Printed Circular Inverted-F Antenna Controlled by a Minimal Set of Parameters
Constantine G. Kakoyiannis†, Aphrodite Kyrligkitsi, Philip Constantinou
1st January 0001
A printed circular inverted-F antenna (CIFA) is mirrored against a small, crescent-like ground plane. The whole radiator is printed on a discoid substrate that conforms to the element and the ground plane. This printed IFA conforms to the circumscribing sphere, and it is an electrically small element designed with only three parameters: two angles and a radius. The CIFA-plus-ground-plane combination is resonant and matched at 2.5 GHz, where it achieved a 3.5% fractional
impedance bandwidth. The antenna is highly efficient (91-95%) and exhibits a near-isotropic far-field pattern (2-dB deviation). The paper also discusses two issues pertinent to the design of electrically small antennas for wireless microsensors: the upper bound on achievable gain and the lower bound on transmit frequency, given the electrical size of the sensor node.
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