CRITERIA FOR SUSTAINABLE PRODUCT DESIGN WITH 3D PRINTING IN THE DEVELOPING WORLD

The demand for consumer goods in the developing world continues to rise as populations and economies grow. As designers, manufacturers, and consumers look for ways to address this growing demand, many are considering the possibilities of 3D printing. Due to 3D printing’s flexibility and relative mobility, it is speculated that 3D printing could help to meet the growing demands of the developing world. While the merits and challenges of distributed manufacturing with 3D printing have been presented, little work has been done to determine the types of products that would be appropriate for such manufacturing. Inspired by the author’s two years of Peace Corps service in the Tanzania and the need for specialty equipment for various projects during that time, an in-depth literature search is undertaken to better understand and summarize the process and capabilities of 3D printing. Human-centered design considerations are developed to focus on the product desirability, the technical feasibility, and the financial viability of using 3D printing within Tanzania. Beginning with concerns of what Tanzanian consumers desire, many concerns later arise in regards to the feasibility of creating products that would be sufficient in strength and quality for the demands of developing world consumers. It is only after these concerns are addressed that the viability of products can be evaluated from an economic perspective. The larger impacts of a product beyond its use are vital in determining how it will affect the social, economic, and environmental well-being of a developing nation such as Tanzania. Thus technology specific criteria are necessary for assessing and quantifying the broader impacts that a 3D-printed product can have within its ecosystem, and appropriate criteria are developed for this purpose. Both sets of criteria are then demonstrated and tested while evaluating the desirability, feasibility, viability, and sustainability of printing a piece of equipment required for the author’s Peace Corps service: a set of Vernier calipers. Required for science educators throughout the country, specialty equipment such as calipers initially appear to be an ideal candidate for 3D printing, though ultimately the printing of calipers is not recommended due to current restrictions in the technology. By examining more specific challenges and opportunities of the products 3D printing can produce, it can be better determined what place 3D printing will have in manufacturing for the developing world. Furthermore, the considerations outlined in this paper could be adapted for other manufacturing technologies and regions of the world, as human centered design and sustainability will be critical in determining how to supply the developing world with the consumer goods it demands.

Study of and design procedure for dual circularly polarized waveguide slot arrays

For the past sixty years, waveguide slot radiator arrays have played a critical role in microwave radar and communication systems. They feature a well-characterized antenna element capable of direct integration into a low-loss feed structure with highly developed and inexpensive manufacturing processes. Waveguide slot radiators comprise some of the highest performance—in terms of side-lobe-level, efficiency, etc. — antenna arrays ever constructed. A wealth of information is available in the open literature regarding design procedures for linearly polarized waveguide slots. By contrast, despite their presence in some of the earliest published reports, little has been presented to date on array designs for circularly polarized (CP) waveguide slots. Moreover, that which has been presented features a classic traveling wave, efficiency-reducing beam tilt. This work proposes a unique CP waveguide slot architecture which mitigates these problems and a thorough design procedure employing widely available, modern computational tools. The proposed array topology features simultaneous dual-CP operation with grating-lobe-free, broadside radiation, high aperture efficiency, and good return loss. A traditional X-Slot CP element is employed with the inclusion of a slow wave structure passive phase shifter to ensure broadside radiation without the need for performance-limiting dielectric loading. It is anticipated this technology will be advantageous for upcoming polarimetric radar and Ka-band SatCom systems. The presented design methodology represents a philosophical shift away from traditional waveguide slot radiator design practices. Rather than providing design curves and/or analytical expressions for equivalent circuit models, simple first-order design rules – generated via parametric studies — are presented with the understanding that device optimization and design will be carried out computationally. A unit-cell, S-parameter based approach provides a sufficient reduction of complexity to permit efficient, accurate device design with attention to realistic, application-specific mechanical tolerances. A transparent, start-to-finish example of the design procedure for a linear sub-array at X-Band is presented. Both unit cell and array performance is calculated via finite element method simulations. Results are confirmed via good agreement with finite difference, time domain calculations. Array performance exhibiting grating-lobe-free, broadside-scanned, dual-CP radiation with better than 20 dB return loss and over 75% aperture efficiency is presented.