Feeder Section Research Articles

Loop Plant Modeling: A Simple Model for Studying Feeder Capacity Expansion

Using a very simple model of feeder cable sizing facilitates the discussion of many interesting questions: How sensitive are sizing decisions to various items of data? How does the need for expensive conduit affect cable size? What kind of economy-of-scale can be expected from consolidating routes into larger backbone configurations? What effect might randomness or uncertainty in the demand forecast have on sizing? How might sizing be affected by limits on available capital? The simple sizing model discussed assumes linear growth of demand over an infinite horizon in an isolated feeder section. The cost of cable or conduit is assumed to be composed of a fixed charge plus a cost per unit of capacity added.

A broadside log-periodic antenna

This invention teaches an antenna array of the broadside type in which dipoles of differing electrical lengths are stacked vertically above and below an imaginary plane with electrical lengths increasing with increasing distance in moving above and below the imaginary plane. The antenna has symmetry in that for each dipole of the array below the imaginary plane, for example, there is a dipole of substantially equal electrical length and spacing approximately the same distance above the imaginary plane. Transposed feeder harness means are employed for joining adjacent dipoles and common output (input) terminals are provided in a position substantially at the location of the imaginary plane. Directional characteristics are obtained by means of Veeing the dipole arms and/or providing a vertically aligned ground screen positioned behind the antenna stack array. In another embodiment a similar array may be positioned immediately behind the first array in place of the ground screen. Directional characteristics may be obtained through coupling an output (input) utilization means to one and then the other of the arrays which are coupled at their feed terminals by means of a transposed feeder section. The array may also be joined with a conventional endfire array, for example, to form a broadside VHF endfire array and an endfire UHF array or conversely, a broadside UHF array and an endfire VHF array. Omnidirectional characteristics may be introduced if such an application is either desired or required by bending or otherwise forming the dipole arms so as to provide a substantially U-shaped configuration for each dipole. As another embodiment the ground screen may be replaced by parasitic elements arranged in a vertically stacked array with the parasitic element being provided for each dipole in the broadside array and being positioned in substantially behind its associated dipole.