Mixtenna: A Self-Biased Nonlinear Patch Antenna for Passive Third-Harmonic Radiation

TL;DR

This paper introduces Mixtenna, a nonlinear patch antenna with embedded diodes that passively generate third-harmonic radiation, enabling efficient frequency up-conversion without external bias.

Contribution

It presents a novel self-biased nonlinear patch antenna design that passively produces third-harmonic signals using embedded Schottky diodes and tailored matching networks.

Findings

Strong third-harmonic generation confirmed by measurements

Excellent agreement between simulations and experimental results

Effective nonlinear loading for passive harmonic control

Abstract

A nonlinear rectangular patch antenna (RPA) is presented in which back-to-back Schottky diodes are embedded at high-field regions to enable passive, bias-free harmonic generation. The self-biased diodes introduce a power-dependent impedance that drives efficient frequency up-conversion and selective third-harmonic radiation. A tailored matching network enhances third-harmonic excitation and coupling while preserving radiation efficiency at the fundamental frequency. Analytical modeling combined with SPICE-assisted full-wave time-domain simulations predicts strong odd-harmonic content, and measurements on RPA prototypes employing SMS7630 diodes confirm these results. Simulated and measured S-parameters and far-field patterns at 925 MHz and 2.775 GHz show excellent agreement. The demonstrated approach establishes nonlinear loading as an effective mechanism for passive harmonic control in compact radiators, enabling frequency-agile and spectrum-efficient antenna systems.