From: Gary McInturff [mailto:[email protected]]
Sent: Thursday, October 28, 2004 4:19 PM
To: [email protected]
Subject: Vertical monopole with counterpoise radiation pattern
Folks,
I'm guessing that for a given dimension above the ground plane
the above antenna radiates isotrophically, correct. (No - I'm not much of an
antenna guy). Just trying to figure out a little about the shielding
integrity test for e-fields in Mil-std- 285.
Thanks
Gary
The radiation pattern of a vertical monopole (around the horizon) is
uniform, so you could call it omni-azimuthal. However, the pattern is a bit
like a donut dropped over the monopole. Maximum radiation is at an elevation
angle somewhat above the horizon. There is a minimum directly above the
monopole, and the field on the horizon is also slightly weaker.
Since these antennas are useful for multi-point communication, or fixed
location to mobile. As most users tend to be at ground level, the monopoles
are often made a bit longer than resonance, which has the effect of
depressing the angle of maximum radiation downward toward the horizon. To
continue the fast-food analogy, sort of like a squashed donut.
OTOH, a vertical monopole is not the optimum choice for aerial
communication; antennas for GPS are a good example of an alternate to
vertical monopoles.
Regards,
Ed
Ed Price
[email protected] WB6WSN
NARTE Certified EMC Engineer & Technician
Electromagnetic Compatibility Lab
Cubic Defense Applications
San Diego, CA USA
858-505-2780 (Voice)
858-505-1583 (Fax)
Military & Avionics EMC Is Our Specialty
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