Multiport Technology: The New Rise of an Old Concept

Abstract

Abstract-A short review of the multiport (six-port) theory for modern applications in downconversion, direct demodulation or modulation of RF signals, and new measurement techniques for localization is presented in this paper. More than four decades ago, the circuit was developed for low-cost S-parameter measurements of microwave circuits. The modifications required to transform original six-port instrument function to radio function was not obvious in the beginning. In this purpose, several innovations have been implemented during the last two decades. Implementations of the circuit in various mature fabrication technologies, covering frequencies from microwave to millimeter wave spectrum, are presented and discussed. Multiport receiver calibration and impairment mitigation techniques are also proposed at frequencies where analog-to-digital converters and digital signal processing are available.

Six-port reflectometer in WR15 metallic waveguide for free-space sensing applications

“…A spatial (related to the spatial phase-shift ∆Φ) Fourier analysis is considered to correct the general forms given by (5) and (6) into the models (7) and (8) that encompasses mismatching and non-linear effects [9].…”

Six-Port Based Interferometry for Precise Radar and Sensing Applications

“…Some years ago, a near-field scanning microscope has been proposed based on the multi-port structure [8]. Even in communication, the six-port concept has been introduced [9,10,11,12]. …”

MHMIC Six-port Interferometer for W-band Transceivers: Design and Characterization

“…Nowadays millimeter wave components are requested more and more for very promising applications, such as multi-Gb/s wireless links, radar and imaging sensors. Six-ports have been used for decades in microwave bands and due to their well-known quadrature down-conversion and direct modulation applications; they also play an important role in millimeter wave transceiver implementation [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. There is an increase in the use of microstrip antenna because of its lightweight, low fabrication costs, the capability of supporting multiple frequency bands, and integration with multiple input multiple output (MIMO) [6].…”