Abstract-A thin dipole antenna is a well-known antenna with linearly polarized wave operation. In this work, a wide-strip dipole antenna is proposed for circularly polarized wave operations. To obtain circularly polarized (CP) wave operations, there are two conditions to be satisfied. One is that the antenna must have two degenerated orthogonal modes with different resonant frequencies. The other is that the phase difference of two orthogonal modes is 90 degrees. To match the first condition, the slab width W is tuned to generate current distributions directed in two different directions. In addition, the second condition is matched by asymmetric feeding point by adjusting the overlapped square width C. The parametric study is completed by the Ansoft HFSS simulator. Simulated results reveal that the CP wave is mainly influenced by the slab width W . The influences of the parameters C and d on the performances of the proposed antenna are also investigated in this paper. Taking −8 dB as reference, there are two working bands for this proposed antenna and the measured center frequencies are 0.66 GHz and 2.04 GHz, respectively, and the corresponding bandwidths are 0.27 GHz (40%) and 1.78 GHz (87%), respectively. In addition, the measured center frequencies and bandwidths of the axial ratio are 1.94 GHz and 0.53 GHz (27%), respectively.Corresponding author: L.-P. Chi (cp531220@ms23.hinet.net). 70Chi et al.

Abstract:For an R&D institution to design a specific high investment cost product, the budget is usually 'large but limited'. To allocate such budget on the directions with key potential benefits (e.g., core technologies) requires, at first and at least, a priority over the involved design criteria, as to discover the relevant decision knowledge for a suitable budgeting plan. Such a problem becomes crucial when the designed product is relevant to the security and military sustainability of a nation, e.g., a next generation fighter. This study presents a science education framework that helps to obtain such knowledge and close the opinion gaps. It involves several main tutorial phases to construct and confirm the set of design criteria, to establish a decision hierarchy, to assess the preferential structures of the decision makers (DMs) (individually or on a group basis), and to perform some decision analyses that are designed to identify the homogeneity and heterogeneity of the opinions in the decision group. The entire framework has been applied in a training course hold in a large R&D institution, while after learning the staff successfully applied these knowledge discovery processes (for planning the budget for the fighter design works and for closing the opinion gaps present). With the staffs' practical exercises, several empirical findings except for the budgeting priority (e.g., the discrimination between 'more important criteria' against the less important ones) are also interesting. For some examples (but not limited to these), it is found that the results from using two measures (statistical correlation vs. geometrical cosine similarity) to identify the opinion gaps are almost identical. It is found that DMs' considerations under various constructs are sometimes consistent, but often hard to be consistent. It is also found that the two methods (degree of divergence (DoD) vs. number of observed subgroups (NSgs)) that are used to understand the opinions' diversity under the constructs are different. The proposed education framework meets the recent trend of data-driven decision-making, and the teaching materials are also some updates to science education.

No abstract

A recent study proposed a systematic “(budgeting) knowledge discovery educational framework” (BKDEF). This BKDEF is focused on guiding staff training courses for enhancing the ability to allocate the “large but limited” budget for single, high-cost product design. However, except for its initial application to support the budget planning for the next generation fighter design, the framework’s effectiveness is still awaiting further scrutiny. This study fills the gap by providing the “second application” of BKDEF, which is to support another similar decision for designing the medium-altitude long-endurance unmanned aerial system (MALE UAS). This paper verified the effectiveness of the framework through an empirical application and obtained the knowledge required to allocate a budget for MALE UAS design following the group-opinion basis. In addition, the original analytical style for the last “decision analysis” phase of BKDEF, which included pure quantitative analytical items in order to understand the similarities and diversities in the individual opinions, was replaced by a comparative study to discover the homogeneity and heterogeneity between the two budgeting decisions in a larger scope. As a consequence, the two criteria sets did not overlap despite both decisions being related to military aircraft design. The absolute weights for the MALE UAS design criteria were more balanced than those for the air-superior fighter design, even if the size of the criteria set was larger. The results pave a way for future studies on how other military aircrafts are designed, as more confidence about the use of a BKDEF can be gained from increasing applications, thus more insightful aerospace knowledge can be exploited in comparisons with these works.

No abstract

This study explores the experts’ opinions during the consultation stage before law-making for civilian drones. A thorough literature study is first undertaken to have the set of influencing factors that should be suitable for the investigation from the perspective of designing and selecting civilian drones. Several rounds of surveys using the Delphi method, followed by an analytic hierarchy process (AHP), are performed to conform to the organized tree structure of constructs and factors and to obtain the knowledge about the opinions of the expert groups, with the expert sample being intentionally partitioned into three opinion groups at the beginning: academia (A), industry (I), and research institutes (R). Doing so facilitates a “mind-mining” process using the triple helix model (THM), while the opinions across the groups can also be visualized and compared. This exploits a new set of knowledge for the design and selection of civilian drones on a scientific yet empirical basis, and the observed differences and similarities among the groups may benefit their future negotiations to propose the drafts for regulating the design, manufacturing, and uses of civilian drones. As several significant implications and insights are also drawn and gained from the abovementioned results eventually, some possible research directions are worthwhile. The proposed hybrid methodological flow is another novelty.

No abstract

A novel printed dipole antenna with helix structure fed by a coplanar waveguide, suitable for 2.4 GHz and 5.2~5.85 GHz WLAN application is presented and investigated in this paper. The helix structure is designed so that the antenna length has a reduction then traditional printed dipole antenna. Some effects of many important parameters on the return loss and gain value of the proposed antenna have been investigated. In order to operate as WLAN device, the dipole antenna with helix structure should be cover the operation bandwidth of the 2.4 GHz and 5.2~5.85 GHz, and omni-directional radiation patterns are achieved at two operating bands.