{http://www.hyperlinktech.com/web/copyrighted_images/hg2408u_thumb.jpg omni} Omni [Antenna] have a broad propagation field, designed to be basically uniform in all directions. In practice, this is not spherical, but often more [Smarties]-like, wide, but not high. The higher the gain, the flatter the [Smarties]. Typical gain of omni's are in the 3dbi-15dbi range. One common and relatively easy to construct type of omnidirectional antenna is the CoaxCollinear. Some omni-directional [Antenna] plans: * (http://www.guerrilla.net/reference/antennas/2ghz_collinear_omni/ Vertical Colinear) from (http://www.guerrilla.net Guerrilla.net) * (http://wireless.gumph.org Easy Homebrew 2.4Ghz Omni) * (http://www.irational.org/sic/radio/omni-aerial.html The Slim Jim) (not 2.4Ghz) At this stage, we have not yet seen a homebrew omni with the combination of decent gain and a suitable radiation pattern (the Smarty is tilted up rather than be level) for the >1km links we're trying to make at MW. Any results to the contrary would be much appreciated! If you want to buy a commercial omni antenna, D-Link sells an 8dbi outdoor omni, as does (http://www.rojone.com.au Rojone). That is, if you missed out on The Incredible Bulk purchase of a few squillion lately. Higher gain ones are available from several US vendors, but the propagation pattern starts to get kinda thin and often has quite a deal of downtilt (which is great if you're on the top of a hill, not so great otherwise). If you really need that kind of gain, maybe you should consider a YagiAntenna or ParabolicAntenna.