Antenna array distributions and their associated patterns are now designed on physical principles, based on placement of zeros of the array polynomial. An overview of the synthesis processes is given. Robust and low Q distributions for linear arrays and circular planar arrays that provide variable sidelobe level pencil beam patterns are treated in detail. Associated difference patterns are included. Individual sidelobes or groups of sidelobes may be adjusted in level. The same technique allows synthesis of an efficient shaped beam, with or without sidelobe adjustment. The ultimate pencil beam array, the superdirective array, is evaluated.>

The field scattered by an antenna contains a component that is the short circuit scattered field normalized by the short circuit current and a second component that is the radiation field normalized by the transmitting current and multiplied by a factor (1- Gamma ). The RCS is the magnitude squared of the difference between two terms, one being the square root of a complex 'structural' cross section, and the other (1- Gamma ) times the square root of a complex 'antenna' cross section. These relationships, and the role of the load impedance are clarified. The connection between antenna directivity and load effective receiving area is also derived.>

Efficiency and input resistance of short monopoles (or dipoles) may be significantly improved through use of a loading coil in series with the monopole wire. The piecewise sinusoidal moment method is used to analyze the loaded monopole. When loaded to resonance, the current rises from the feed value to a peak slightly beyond the load point with decay to zero at the end. Radiation resistance improvement factors as large as 5 have been calculated. The resonant loading reactance is shown to vary inversely with the antenna length for most lengths. Efficiency varies slowly with load point and peaks at roughly 0.4 from the feed, in contrast to earlier approximate theory that predicted higher efficiency for loads farther out toward the end. The curves allow a tradeoff between slightly reduced efficiency and larger input resistance (to allow easier matching) to be made. For this case, a 2/3 loading point may be a good compromise. The length for which efficiency is 50 percent is a useful design guide. This length varies slowly withQandh/aand is in the range 0.06 to 0.09 λ. Thus shorter monopoles will have low efficiency. Bandwidth is improved due to loading coil losses at the expense of efficiency; lossless loading bandwidth is unchanged over the unloaded monopole as the radiation resistance and reactance slope increase commensurately. Extensive graphical data are presented.