PowerPoint 2011 and 2016 don't retain vector graphics from PDF files; they get converted into bitmap graphics when the presentation is saved. This can be avoided by using a [.WMF or .EMF file (Windows Metafile / Enhanced Metafile)][1] instead of PDF. WMF is Microsoft's own portable graphics format from the Windows world and can contain bitmap elements and vector elements. 

To embed vector graphics from a PDF file in a PowerPoint presentation, the PDF file will need to be converted to a WMF or EMF file, but it would be preferable to get a WMF or EMF file exported directly from the software used to create the graphics in the first place. Vector graphics editors like *Adobe Illustrator* and *Inkscape* as well as *OpenOffice Draw* can export WMF/EMF files. (*Affinity Designer* currently not so.) The possible downside is that complex graphics effects from a PDF-based application like Illustrator may be rendered wrong in the WMF/EMF format, which then makes it necessary to convert the vector graphics into bitmap graphics after all. 

For conversion, there are commercially sold conversion utilities and free websites. There are also tools to convert PDF files directly to PP presentations (.pptx files), but I'm not sure about the quality of these solutions, e.g., whether they just convert vector graphics to bitmap graphics...

Using vector graphics applications for export or conversion:

• **Adobe Illustrator** can export to the WMF and EMF format, so if AI is at hand, open the PDF file in AI and choose `File` > `Export…`, then choose `"Windows Metafile wmf"` from the format selection in the dialog box.

• **Inkscape** (open source software) can export to the WMF format (`File` > `Save As…`), and placing the WMF files created in Inkscape seems to work fine. But when importing and re-exporting existing PDFs with complex graphics, e.g., from Illustrator, the result may differ from the original.

Wikipedia has a [comparison of vector graphics applications][2] with their export formats.

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If this is all too much trouble and you want to keep at least a high-resolution bitmap image, the best workaround is to convert the PDF into a high-resolution image yourself, e.g., by using the Preview application to open and export the PDF as PNG. (Beware: Depending on the source of the PDF file, it may contain low-resolution bitmap graphics, which can not be 'upscaled' without visible pixelation.) 

After placing the image, it's important to adjust PowerPoint's automatic image compression setting **before you save** the presentation: Choose `File` > `Reduce File Size`, and in the dialog box select `"Keep Current Resolution"`from the drop-down menu.


  [1]: https://en.wikipedia.org/wiki/Windows_Metafile
  [2]: https://en.wikipedia.org/wiki/Comparison_of_vector_graphics_editors#Export