Medstar Montgomery Medical Center Linked to MAIPN Backbone

On Sunday, April 28, a dish was added to the existing MAIPN backbone node in Aston, MD, establishing a link to Medstar Montgomery Medical Center in Olney. Here are a few photos.

We want to express our appreciation to Tony, K3WX, for hosting a MAIPN backbone node on his commercial tower in Ashton.

View of the penthouse structure atop MedStar Montgomery Medical Center, showing the MAIPN dish attached to the side of the penthouse immediately below the roof line.
The MAIPN dish is visible on the right side of the hospital penthouse.
View of the tower in Ashton, MD, with the dish being lifted into place.
Adam, KC3GQU is on the tower at the 160′ level. Mike, NC3M is hauling the dish up to Adam, while Dick, WN3R steers using a tagline (black rope).
View of the tower from the ground up.
Adam maneuvering the dish into position while Dick and Mike “supervise.”
The photo is described in the caption.
Adam snapped this view to the west overlooking the dish following installation. The Olney water tower, about 3.7 miles distant and marked by the arrow, is barely visible above the trees. The hospital is about two blocks north of water tower, across Route 108. Although hidden by the trees from this vantage point, the hospital is just to the right of the water tower.

The diagram below illustrates some of the planning we do prior to installation.

The diagram is described in the text.
Elevation profile of the path, based on Google Earth.

We start with an elevation profile obtained from Google Earth, and sketch in the dish heights above ground level at both ends of the link. The path length in this case is 3.73 miles. We obtain the diameter of the Fresnel zone from this website:

Note that the downtilt is exaggerated in this diagram, because the horizontal and vertical scales are different. (The actual downtilt is a small fraction of a degree.) Nevertheless, we can easily read off the height of the path above ground level at any point along the path.

In this diagram, we have assumed that the height of the dish on the tower was 100′ above ground. This indicates we have a problem, because the center of the path is only 55′ above an intervening ridge, and trees on that ridge are approximately 100′ high. Getting the dish on the tower up to the 160′ level helps, but doesn’t resolve the problem.

The inset (again, from Google Earth) shows what’s on the ground where the path crosses over the problematic ridge. Fortunately, there is a partial clearing surrounding a house, but we have to accept any loss due to the trees until we can find a better path.