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While fundraising efforts for our ambitious Array2k project continue, we have received grants from the American Astronomical Society, the Second Foundation, and the ARRL Foundation, to begin construction of an eight-dish prototype. Dubbed the Very Small Array (VSA), this 1296 MHz antenna system is slowly taking shape in the backyard of executive director H. Paul Shuch's rural Pennsylvania home. It will be used to test reception of our ham radio Moonbounce Beacon.

In the Autumn of 2001, Pennsylvania College of Technology civil engineering student Timothy Wentz used a theodolite, a clock, ephemeris tables and the Sun to lay out precise North-South and East-West baselines for the VSA (an Array2k prototype). thumbnail

Here civil engineering student Timothy Wentz is staking out the precise location for the first of the VSA's eight dishes. thumbnail

Come spring thaw, we were able to begin digging holes for the mounting pipes. Seen here is a 24 inch diameter auger being aligned with the first stake. thumbnail

Fortunately, the ground was soft, and the soil moist from the recently melted winter snows. The first hole was easily dug to a depth of 42 inches... thumbnail

...and a significant quantity of topsoil and shale removed from it. Each of the holes will be filled with 0.4 cubic yards of concrete. (Pardon, please, the awkward non-metric measure. That is the way concrete is sold in the US.) thumbnail

The last of the eight holes for the VSA was drilled on 28 February 2002. Though technically still Northern hemisphere winter, temperatures of a comfortable +2 degrees Celsius prevailed. thumbnail

With all eight holes in place, it appears as though Dr. Shuch's back yard has been attacked by an alien race of giant gophers! thumbnail

Just a few of the 112 (wow!) bags of concrete, weighing in at just under 9,000 pounds (ugh!) needed to set the eight antenna masts into the ground. That's about four metric tonnes of concrete to plant the eight-dish VSA. thumbnail

For antenna masts, the VSA is using eight twelve-foot lengths of 4" OD Schedule 40 galvanized steel pipe. thumbnail

Setting the first few pipes in the holes, and preparing to mix concrete. For a single dish, our Argonauts frequently mix concrete by hand, with a hoe in a wheelbarrow. For eight dishes, a rented gasoline-powered mixer is easily justified. thumbnail

The patio thermometer shows that it was comfortably above freezing when we began to plant the eight antenna masts in their respective holes in the ground. thumbnail

Each antenna mast is set on concrete blocks in the hole. The pipe is drilled, and a length of steel reinforcing bar passed through it, to prevent the mast from twisting in its concrete base. thumbnail

Guy wires and bubble levels help the workers to true the masts. The levels need to be placed near the top of the pipe, spaced ninety degrees apart. thumbnail

Magnetic levels, which secure themselves to the steel pipes, make the job of leveling the antenna masts much easier. thumbnail

The guy wires, attached to wooden stakes in the ground, are temporary. They hold the mast in position while the concrete is being poured. thumbnail

Yes, this antenna mast is vertical. Central Pennsylvania's rolling terrain is not even close to level. This will necessitate trimming the masts after installation, to ensure that all eight dishes end up at the same absolute altitude. thumbnail

The concrete is mixed with water, six bags at a time. Each wheelbarrowful of concrete dumped into the holes weighs about 500 pounds. thumbnail

Each antenna mast will receive a total of 14 bags of mixed concrete, totaling around 1200 pounds. This design will allow the antennas to survive sustained winds of up to 90 MPH. thumbnail

Each hole is filled with concrete to within a few inches of ground level. This allows topsoil to be shoveled over the concrete, and grass to grow right up to the antenna mast. thumbnail

As of the first day of March, 2002, it was four masts up, four to go. The strings verify the proper placement of the masts, crossing at the array phase center, at exactly a 90 degree angle. thumbnail

Just one day later, all eight antenna masts were up, awaiting being trimmed to the appropriate heights. thumbnail

Cutting the masts down to size. A string level was used to determine the trim line for each mast, so that all dishes will be at the same absolute height. thumbnail

The eight masts all trimmed to the required height, and painted brown to help them blend into the surrounding terrain. Once the dishes are mounded to the masts, a ring of trees will be planted around the array, out of respect for neighborhood aesthetics. thumbnail

Forty Arbor Vitae being delivered to the VSA site. These trees, now only eight feet tall, will grow to a height of some twenty feet or more, completely blocking the antennas from view. thumbnail

Placing the Arbor Vitae around the poles of the VSA, in preparation for digging the holes and planting them. thumbnail

Workers planting the last of a ring of trees around the eight antenna masts of the Very Small Array. thumbnail

In the middle of VSA Grove, the first of eight dishes is mounted to its mast. The diagonal jackscrew running from the rear center of the dish to the right hand side of the pole provides manual elevation control. Eventually, it will be replaced by a motorized jackscrew, and all eight dishes synchronized to a common declination control box. thumbnail

The first VSA antenna is clearly visible, viewed through the line of trees. Within one to two years, once the trees have filled in, none of the dishes will be visible from anywhere on the adjacent property. See this editorial on Being a Good Neighbor. thumbnail

Lewis Carroll wrote about painting the roses red. Through a different looking glass, here is Dr. SETI painting the dishes green. thumbnail

Painted with Adirondak Green exterior latex house paint, and viewed through VSA Grove, the first dish blends nicely into the background. thumbnail

The Flag of Earth flys proudly from the first dish of the Very Small Array. It underscores the global nature of The SETI League, the VSA, and the entire SETI enterprise. thumbnail

Seven more az-el mounts (reminiscent of the Pleiades, the constellation also known as the Seven Sisters) are installed on their VSA masts, awaiting delivery of the remaining seven dishes. thumbnail

thumbnail The rapidly growing VSA, as viewed from above (left) and below (right). thumbnail

The next step was to mount offset feedhorn-support tripods on the reflectors. As these dishes are designed for non-blocked apertures, the feed points appear significantly off-center. thumbnail

The VSA nears completion, with eight dishes up on azimuth-elevation mounts, and eight L-band feedhorns in position. Now we can start on the true challenge, designing and testing the electronics for combining all these signals. thumbnail

A view from ground level shows how the grove of arbor vitae and the selected color scheme combine to help mask the eight dishes of the VSA from view. thumbnail

The VSA phasing matrix begins to take shape on the bench. These bias tees and power dividers/combiners will produce four different beam patterns simultaneously, in two orthoginal circular polarizations. thumbnail

VSA volunteers Steve Berger and Jack Weaver, using a rented back-hoe to dig the main cable trench. thumbnail

Two runs of PVC conduit, one carrying coaxial cables and the other for power wiring, are laid in the 33.5 meter long trench. thumbnail

Secondary trenches running along the North-South and East-West baselines will house additional conduits, to carry signals from the eight dishes to phase-combining networks, which will be located in a weatherproof box at the intersection of the trenches. thumbnail

Conduit from each of the dishes, as well as the main conduit run into the station, connects to the main circuit box at the center of the array. thumbnail

Inside the VSA's main junction box, a jumble of cables awaits the installation of a plethora of connectors. thumbnail

Winter has come early to Northern Pennsylvania this year, turning back to white dishes once painted green. This 30 October 2002 photo shows snow falling on still-turning leaves. Thus, all outdoor work on the Very Small Array is suspended until further notice, giving us time to work on the required Low Noise Amplifier design.

The prototype Low Noise Amplifier for the Very Small Array is based upon the Down East Microwave 23ULNACK kits constructed at the SETICon03 Hardware Workshop. Modifications include noise matching for 1.4 GHz, and the addition of a second gain stage. At the 2003 Central States VHF Conference, this prototype measured 0.53 dB noise figure at +31.2 dB gain.

US Patent #6,593,876, "Adaptive Microwave Antenna Array," was granted to Executive Director H. Paul Shuch, and assigned to The SETI League, on 15 July 2003. The patent covers key aspects of the VSA's signal combining technology. See this Press Release for further details.

Dish Array in Disarray:

Although the snow was light in December of 2003, the winds were heavy, resulting in each of the eight dishes of the Very Small Array choosing its own target.


This power combiner assembly for the VSA is constructed out of surplus components mostly acquired on eBay. Sixteen type N recepticals on the back panel provide a means of connecting the feedlines from the antenna-mounted VSA preamplifers (eight each vertically and horizontally polarized) to the eight quadrature hybrids (blue modules at the rear of the box). These produce eight RHCP and eight LHCP signal components, which are connected via phase-matched cables to a pair of eight-way L-band power combiners, mounted on the bottom of the enclosure. The output ports from each of the two power combiners feed a cascade consisting of a 20 dB gain line amplifier (on the right side of the box), a variable attenuator (mounted on the front wall of the box), and then a second buffer amplifier, before being routed to the output connectors on the rear panel (one each for RHCP and LHCP). On the left side of the box is a power supply to provide operating potential to the line amplifiers. The attenuators allow the amplitudes of the two orthogonal circular polarizations to be equalized.

Aerial view of the VSA, courtesy of Google Earth. The 3.7 meter dish for Project Argus station FN11lh is visible near the center of the image. The eight dishes of the VSA can be seen in a cross configuration toward the upper left of the image, ringed by a grove of trees. Executive Director H. Paul Shuch's house can be seen toward the lower right. In the driveway is Dr. Shuch's minivan, with its "DRSETI" license plate (unfortunately, not visible from space).

A decade after they were planted, the forty tiny Arbor Vitae ringing the Very Small Array have grown into mature trees, completely obscuring the dishes from view and placating concerned neighbors who prefer the wonders of nature to "the terrors of technology".

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