Designs of third harmonic generators using a left-handed nonlinear transmission line on microstrip-line and suspended stripline

In this paper, designs of an effective third harmonic generator using a left-handed nonlinear transmission line (LH NLTL) are presented. The proposed harmonic generator using the LH NLTL is composed of a series of varactor diodes and shunt inductances implemented on microstrip-line (MSL) and suspended stripline (SSL). Both of the harmonic generators were built on a Rogers RO4003 substrate and has dimensions of 12 mm by 7 mm. The fabricated LH NLTL provides insertion loss from 1.7 dB to 4.7 dB for a wide left-handed passband from 2.6 to 18 GHz. The measured minimum third harmonic conversion loss was 14.2 dB at an input frequency of 2.5 GHz. When compared to previous works, better third harmonic conversion efficiency is achieved with much smaller size at lower frequencies.