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Vertical Radiation Pattern?
This may be a little off topic, but here goes anyway.
I have read somewhere that vertical antennas radiate almost nothing below the lowest elevation of the antenna. So, I was wondering if a wireless router also radiates almost nothing below the router. (The antenna of a wireless router is usually pointing up.) These devices usually operate at 2.45 GHz. I know that routers usually have other means of security, but I was wondering if I could also locate the router such that the radiation was limited or non-existent in one direction. Thanks, jimbo |
#2
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This may be a little off topic, but here goes anyway.
I have read somewhere that vertical antennas radiate almost nothing below the lowest elevation of the antenna. Well, a half-wave vertical dipole in free space radiates a pattern aimed towards the horizon. There's significant radiation both above and below the horizon. There are deep nulls directly above and below the antenna, but the null isn't terribly deep once you get more than, say, 20 degrees on one side of the axis of the antenna. I know that routers usually have other means of security, but I was wondering if I could also locate the router such that the radiation was limited or non-existent in one direction. I wouldn't count on this at all. Although the pattern will be weaker in the axis of the antenna, this sort of antenna system is not in free space. There are all sorts of reflections from metal objects in the building, and these will tend to fill in the nulls to some extent. The nulling is sufficient to help reduce interference (to some extent) between access points located right above one another on different floors of a building, but it's not completely effective even at that, and should not be counted on for security or privacy. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
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