Abstract-In the strive for knowledge discovery in a world of ever-growing data collection, it is important that even if a dataset is altered to preserve people's privacy, the information in the dataset retains as much quality as possible. In this context, "quality" refers to the accuracy or usefulness of the information retrievable from a dataset. Defining and measuring the loss of information after meeting privacy requirements proves difficult however. Index Terms-Anonymization, data mining, data quality, privacy preserving data mining. I. INTRODUCTIONWithin the Privacy Preserving Data Publishing (PPDP) community, preventing sensitive information about individuals from being inferred is a top priority. This is known as "anonymization". One of the key concepts in PPDP is the trade-off that is inherently present when "anonymizing" data: balancing the increase in security with the decrease in information quality. The majority of previous work has focused on the difficult problem of defining and measuring privacy [1], [2]. This paper explores the other side of the trade-off: information quality. A lot of the time, simplistic measures are developed to provide an estimate of the information quality, or statistical techniques are borrowed from the SDC (Statistical Disclosure Control) community. While robust, these evaluation techniques often fail to capture the nuances that can be present when evaluating specific anonymization tasks, such as generalization 1 1 "Generalization" refers to making a value vaguer, such as changing all occurrences of "apple" and "banana" to "fruit".2 A "dataset" is a two dimensional table where rows represent independent records (tuples) and columns represent various attributes that describe the records and distinguish them from each other.In PPDP, the information quality of an anonymized dataset is most often evaluated by measuring the similarity between the anonymized dataset and the original dataset. If the dataset could be used for a variety of reasons and there is no single purpose in mind, the dataset is evaluated in a way that applies to any scenario -we refer to this as measuring the "dataset quality" or "dataset information loss". These types of techniques are discussed in Section II.Alternatively, if the purpose of the dataset is specific and known, the information quality can be measured in respect to that purpose. Privacy Preserving Data Mining (PPDM; a sect of PPDP) focuses on this type of data, where the quality of the dataset itself is less important than the quality of the outputted data mining 3 results produced from the dataset. Common purposes are classification 4 and clustering 5 [2]. Many patterns in the dataset can be lost after anonymization, even if the dataset itself appears to retain most of its statistical information [6]- [8]. For this reason, information measures have been designed that specifically look at the effect of anonymization on data mining results, and we discuss these in Section III. We call this type of information quality, "data mining quality" or ...

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This paper presents an investigation on the waveguide of circularly polarised radial line slot array (RLSA) antennas to improve gain and radiation bandwidth. Two circularly polarised (CP) RLSA antennas were designed with two different waveguide configurations. In the first configuration the waveguide is fully filled with dielectric materials and in the second configuration the waveguide is partially filled with dielectric materials and rest of the waveguide is filled with air. Numerical results of these two CP-RLSA antennas with two different waveguide configurations are presented and compared. Significant improvements have been made in the 3-dB directivity bandwidth and aperture efficiency of the antenna having waveguide partially filled with dielectric material. The 3-dB directivity bandwidth was measured 6.2% and aperture efficiency increased to 55.5%. The CP-RLSA antenna has also achieved a peak directivity of 31.7 dBic and a gain of 31.2 dBic as compared to the directivity 30.1 dBic and gain 29.5 dBic, respectively achieved with the CP-RLSA antenna having waveguide fully filled with dielectric material.

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