Over on the RTL-SDR Facebook Page, Boris Lukac has shared a link to an Instructable by tigers58 for a omnidirectional fractal HDTV antenna. The simple build covers 50-1100MHz making it perfect for general use with a RTL-SDR and for grabbing some extra HDTV channels when not hooked up to your dongle. The supplies needed to build the antenna may already be laying around your home or workbench:

A piece of poster board or suitble material Printer with paper to print out the pattern PDF Tape Scissors Thumb-tack (or other sharp pointy tool) 10.5 ft of 22-24 AWG copper/aluminum wire Crimp connector and tool to crimp with A length of 300 Ohm Twin Lead, or, an in-line 300 Ohm to 75 Ohm matching transformer (tigers58 also states he has had success with just directly connecting RG-6 coax to the antenna leads) Other tools such as a screwdriver for attaching the antenna leads to the matching transformer and craft knife or other small sharp blade for cutting slots into poster board.

“After reading an article about the use of fractal mathematics in the design of cell phone antennas that have incredible bandwidth in spite of their extremely small size, I began to experiment with using a very simple fractal pattern, the Koch Snowflake, as the basis for an easy to build indoor HDTV antenna. The result of that experimentation is presented here as what I believe to be not only the best DIY HDTV antenna, but the also the simplest to build, not only in terms of the materials needed, but also in the labor required. As the holder of an Extra Class amateur radio license, I know there is no such thing as a “magic” antenna, but I started referring to this antenna as the magic antenna when I discovered that it had such amazing bandwidth, covering digital channels 2 through 60. So, with that in mind, let’s get started.” — tigers58

With many people already having these items on hand, this could be a quick cheap project to help increase the signals you are able to pick up with your RTL-SDR Dongle. Be sure to check out the Instructable page for all the steps needed to build this antenna. Keep in mind, with a wideband antenna like this, it may introduce more noise. Depending where you live and what is around your antenna, your results may very. Keeping the antenna flat may also allow for more directionality while reducing noise from sources out of the direction you wish to receive.