Equivalent Circuit Model Separating Dissipative and Radiative Losses for the Systematic Design of Efficient Microstrip-Based On-Chip Antennas

Abstract

This article presents a comprehensive method to efficiently design capacitively enhanced resonant on-chip antennas using an equivalent circuit (EC) model instead of computationally demanding full-wave simulations. To systemize the design process by predicting the radiation efficiency, the input impedance, the current and voltage distributions, and the radiation pattern of the antenna based on an EC, a method to extract both dissipation and radiation mechanisms from full-wave simulation data is described and carried out. Based on this separation of loss mechanisms, an EC-based antenna optimization with respect to the radiation efficiency is conceivably possible. Additional to the EC, which enables this efficient antenna optimization and increases the physical insight in the radiation mechanism, an analytical estimation of key antenna parameters, as the resonant length, is presented. The results from the analytical calculations and the antenna parameters calculated using the EC model are compared with full-wave FDTD simulations and used to discuss the capabilities and limitations of the EC model. Finally, an on-chip antenna of the considered type operating at 290-300 GHz and manufactured with silicon-germanium technology is used to verify the full-wave antenna simulations and the presented approach in general. Index Terms-Antennas' theory and design, equivalent circuit (EC), millimeter-wave and terahertz components, passive component modeling, silicon-germanium (SiGe/Si) technologies. I. INTRODUCTIONT HE need for highly efficient mm-wave on-chip antennas manifests in numerous applications, namely high-resolution radar imaging [1], detailed material characterization [2], and high-data-rate communication [3]. A key parameter to increase the performance of the overall system is reducing the loss contributions of the transducer between the front end and free space, namely the antenna. These loss Manuscript

Bandwidth-Enhanced Circularly Polarized mm-Wave Antenna With On-Chip Ground Plane

“…Section II B). Since both conductor and dielectric losses usually allow for only moderate radiation efficiencies, special attention is paid to increasing the radiation efficiency by inserting a capacitive discontinuity [15], [16]. elements will be referred to as A and B.…”

“…At resonance, the high impedance at the feeding point will result in a low current and thus comparably smaller losses in the narrow part of the tapered section. Along the antenna length, the current increases towards the short, only affected by the discontinuity as discussed in [16]. The discontinuities are controlled by the overlap of the top aluminum and the underlying copper layer (cf.…”

“…Based on the equivalent circuit (EC) from [16], an ECmodel for the dipole arms is depicted in Fig. 2.…”

“…Thus, the detection of simple targets demands different polarized Tx and Rx antennas or a quadrature hybrid coupler, which feeds two orthogonal polarizations, as in [8]. The antenna introduced here utilizes capacitive discontinuities in quarter-wavelength grounded dipole arms to increase the radiation efficiency [15], [16]. Furthermore, the full antenna design process is presented and characterization of the antenna's polarization up to 280 GHz is carried out utilizing a rotating rectangular waveguide and maintaining a phase-correct antenna measurement.…”

The Impact of Group Delay Dispersion on Radar Imaging With Multiresonant Antennas

“…In this letter, we analyze a circular-polarized multiresonant antenna with an on-chip ground plane. Multiple resonant structures increase bandwidth and series capacitive elements enhance the radiation efficiency (similar to [16]). This has the advantage that no complex and additional manufacturing processes are necessary as with the previously mentioned approaches.…”