The log periodic antenna is a particularly useful design when modest levels of gain are required, combined with wideband operation.
A typical example of this type of RF antenna design will provide between 4 and 6 dB gain over a bandwidth of 2:1 while retaining an SWR level of better than 1.3:1. With this level of performance it is ideal for many applications, although a log periodic antenna will be much larger than a Yagi that will produce equivalent gain. However the Yagi is unable to operate over such a wide bandwidth
Specification