Practical and Cost-Effective Bias Line Implementations for Reconfigurable Antennas

Bias lines form an integral part of the reconfigurable antenna design process. Current methodologies for bias lines are either too narrowband or require a relatively large amount of real-estate that may not be available. Also, metallic lines are unsuitable for designs with strong fields in the bias line location. Bias lines using resistive materials are often prototyped using microfabrication facilities, but these facilities might not always be accessible. This letter investigates a novel, practical, and cost-effective bias line solution using conductive adhesives. These resistive lines effectively attenuate the RF signals providing good isolation between the RF and the dc signals while still passing a dc voltage to activate the switches. The reconfigurable E-shaped patch antenna is used as a case study in this letter, and some issues when using metallic lines in this type of antenna are also presented. The newly proposed bias line aims to minimize those issues shown hereafter. The fabrication process is also enumerated for those interested in repeating these designs for other applications. Overall, the S₁₁ and pattern measurements show good agreement with the simulations and prove their effectiveness experimentally.