Related Experiment Video
Updated: Aug 14, 2026

Effective Analysis of Human Exposure Conditions with Body-worn Dosimeters in the 2.4 GHz Band
Published on: May 2, 2018
Improved Asymptotic Friis Formula with Higher-Order Terms: Calculating Antenna Coupling in Close Proximity
1Department of Electrical and Electronics Engineering, Sejong Cyber University, Seoul 05000, Republic of Korea.
Abstract:
The emergence of near-field communication as a part of sixth-generation (6G) communication necessitates accurate estimation of the link budget between two antennas operating in the near-field region. In this paper, we present an asymptotic expression for the gain reduction factor that includes higher-order terms to evaluate the accuracy of predicting antenna coupling at short distances in the near-field region. Asymptotic Friis formulas with gain reduction factors for both circular and rectangular apertures are examined, and we show that asymptotic formulas including higher-order terms yield a 22-25% shorter minimum prediction distance than those with lower-order terms. The validity of the formula is evaluated through the full-wave simulation and measurement.
Related Concept Videos
Mesh Analysis for AC Circuits
The process of harmonizing these impedances begins with a clear understanding of the input and output signals. Once these signals are known, the...
Polar Coordinates: Problem Solving
Surface Area Calculations
Parallel Resonance
¹H NMR: Long-Range Coupling
In alkenes, spin information is communicated via σ–π overlap, as seen in allylic (four-bond) and homoallylic (five-bond) couplings. These coupling interactions are stronger when the σ bond is parallel to the alkene π orbitals.
The Maximum Power Transfer Theorem
The load connected draws the current, and the circuit delivers the power to the load. The alternating current flowing through the load is determined using the rectangular form of voltages, currents, network impedance, and load impedance. The average power delivered to the load is obtained from the product of the square of current and load resistance.