The clever arrangement of actively driving only one dipole while letting the other parasitic dipoles be coupled to the driven element through mutual field coupling is the salient feature of a Yagi antenna. Hence the Yagi is actually a dipole array. All other electrically unconnected sets of dipoles are called parasitic elements and are geometrically placed in parallel to the driven element at various distances away from the driven element. The single dipole which is directly power by the transmitter is the primary dipole called the driven element. All the other dipoles of the array barring only one dipole element are not electrically connected to the transmitter. In simple terms, a Yagi antenna is an array of dipoles geometrically arranged in the plane of the primary driven dipole. However, some might ask, what is the unique concept that makes a Yagi antenna tick? What makes it distinctively different from other types of antennas? вЂ¦ Fair question! We will try to examine some of the fundamentals of a Yagi-Uda antenna. Perhaps, we all know that a Yagi antenna provides a unidirectional radiation lobe pattern and enhanced forward gain in comparison to a dipole. Hence we have called this type of antenna as the Yagi-Uda antenna or more popularly as the Yagi antenna. This concept was further refined by the work of countless people over the years but this path-breaking antenna structure was dedicated to prof. Hidetsugu Yagi of Tohuku Imperial University, Japan did pioneering work and created the concept of beamforming of antenna radiation by utilizing parasitic elements placed in close proximity to the radiating element. You will find the best information on ultra-high gain Yagi antennas published on Earth Moon Earth (EME) Yagi Antennas.A Yagi-Uda antenna popularly known as the Yagi antenna is perhaps one of the finest inventions ever made in the field of antennas that revolutionized the world of radio communication. Use this calculator to understand the scope of your antenna project, if you want more gain but play it safe by using a design that has been built and tested. This means the calculations are based on mid-range values for dimensions, nothing here is pushing the envelope and is appropriate for the 6 to 10 dB Yagi builder. The results from this calculator are in line with current commercial practice and amateur radio design in use today. Like other calculators the results will vary as there are many designs each with variations in formulas since Uda and Yagi invented the antenna we now know as the Yagi in 1926. These are the general characteristics of the Yagi! Use this calculator as a tool to understand and planning of your Yagi Antenna. Overall wide Director spacing gives more gain than more closely spaced Directors. The rest of the Directors spacing has less impact. The most important element spacing is the reflector and first director. Element spacing is the second factor in gain. As Directors are added more boom length is needed so more gain is linked to both. Just a three elements are required Reflector, Drive Element (dipole or loop) and a Director gives about 5 dB gain. Long and slider is the look as the number of elements and boom length the biggest factor in gain. Gain is the motivation to build the Yagi antenna. The Yagi, one of the most popular directional antennas

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