YO.EXE is a Yagi-Uda antenna analysis and optimization program for IBM-PC and compatible computers. YO will analyze a Yagi hundreds of times faster than general-purpose antenna modeling programs, such as MININEC or MN A fast Yagi model is implemented with high accuracy for forward gain and overall pattern, and good accuracy for F/B and input impedance. The Yagi model used in YO is significantly more complex than the well-known W2PV Yagi model YO includes an algorithm for automatically optimizing the forward gain radiation pattern, and input impedance of a Yagi. This algorithm simultaneously adjusts all element lengths and spacings to iteratively converge an antenna design to an optimal set of dimensions, using performance criteria and objectives which you specify The Yagi analysis algorithm used in YO employs a method-of-moments solution for element currents. It includes correction factors to prevent convergence to supergain geometries, and to more closely match the YO-computed gain and pattern to those obtained with MN. Compared with MN, the accurate arbitrary-geometry antenna modeling program based on MININEC, YO is typically within 0.1 dB for forward gain, within a few dB for F/B, and within a couple of ohms for input impedance. Patterns produced by YO and MN for the same Yagi usually appear nearly identical. Occasionally, F/B differences of 10 dB or more will occur for unusual Yagis which YO computes as having all backlobes more than 30 dB down The speed of the YO Yagi analysis algorithm permits several Yagi iterations per second to be performed for small Yagis (8 MHz XT with 8087 Using YO, a small beam can be completely optimized for gain, pattern, and SWR over a frequency band in just a few minutes. For antennas having many elements, such as long-boom VHF Yagis, the optimizer may be run unattended with constraints to automatically find the best antenna -- while you sleep, if necessary. Yagis having up to 50 elements can be modeled YO will analyze a Yagi at a spot-frequency or at the low, middle, and high frequencies of a band of interest. It will update plots on your screen of the far-field radiation patterns at each frequency while it iterates the Yagi dimensions, and will continuously display the forward gain, F/B, input impedance, and SWR. This running graphics/alphanumeric display lets you interactively direct the optimization. You may interrupt the optimization at any time to save the current design or to change optimization strategy
