On 10/29/2014 02:30 AM, Arfa Daily wrote:

snip



Well, I'm calling it weak because most radios won't get it, but Wikip
says that it's 50,000 watts ERF (sp?) but 88.1 is only 15,500 watts.
(also ERF? It didnt' say.)


ERP - Effective Radiated Power ? The 'real' transmitter output
multiplied by the 'gain' of the transmitting antenna.


So maybe I'm calling it weak because it
farther away, in DC, not Baltimore where I live,


There are many many factors that affect the propagation of a VHF signal
over a lower frequency one, some of which will degrade that signal, and
others of which can, under the right conditions, enhance it. VHF signal
reception is a lottery, once you are outside the designed service area
of the station.


but actually, there are
places north of here, farther from DC, the Westminster, Md. area, where
88.5 comes in well and 88.1 barely comes in. A friend moved to
Finksberg and she had to change to 88.5.

But maybe the FCC makes them arrange their antennas so that in the city
of Baltimore and its populous suburbs, 88.5 doesn't overpower 88.1.
But the frequencies are different, and there's no Baltimore 88.5, so why
would 88.5's antennas have to avoid the populous part of Baltimore, or
any part?


Without seeing a published map of the station's service area, it's
impossible to say. However, something as simple as a tall building in
the direction of the transmitting site, can be enough to cast a 'radio
shadow' across a large swathe of territory on the 'downstream' side

Arfa


Michael


An obstruction in the energy field creates Fresnel Zones on the side of
the obstruction opposite the antenna. These are alternating peaks higher
than normal and dips lower than normal. The distance between the peaks
and nulls (Fresnel Zones) is determined by the distance between the
antenna and the obstruction.