Connections:

I am showing COAA PlanePlotter as PC software here just because it is most often used application together with the Mode-S Beast. Several others should also run with it, as there are

Jetvision.de "Globe-S", which should soon support the Mode-S Beast
I guess that also Sprut's ADS-B Scope should do it
I also believe that there is a software from USA that can run with it, I was in contact with the author and also got some postprocessed data back, but yet don't know more (funny, yes)

Basically, all PC software that can handle AVR format can be used for the Mode-S Beast.

GUI: Graphical User Interface

Standard Connection 1CH via USB:

The basic connection is as simple as this graphic: Just connect an antenna to the SMA connector, and the USB cable to your PC. Do some simple installations scripts and you are ready.

Standard Connection 2CH/4CH via USB, omni antenna plus yagis:

...

The big advantage of the Mode-S Beast is the possibility of connecting more than just one antenna to the receiver by using external miniADSB receivers. The 2CH unit allows up to two antennas, while the 4CH unit allows up to a total of 4 antennas to be connected. Basically every receiver can be connected here as soon as its signal level is around 1,65Vpp. DC biasing is done separately anyway.

I am using exactly above configuration:

The G7RGQ stacked omni directional antenna connected to the internal receiver provides data from all directions
The 10ele yagi, built using existing material using the yagi designer by VK4DI, points to the closeby Munich airport and receives all ground traffic from there. On the omni this did not show up, even it is just 20nm, due to mostly 2 reasons: 1) too less gain and so too weak signal of the omni and 2) too much FRUIT from other planes

I will create a page about some Mode-S accessoirs as soon as this project allows, e.g. the yagi, a 3dB signal splitter, how to build the G4RGQ omni and maybe some more.

Enhanced Connection 2CH/4CH (Antenna Segmentation):

There is a basic problem in the Mode-S transmissions, which is so called FRUIT. This means that the channel is acutally shared by many applications, like DME (Distance Measuring Equipment) and traditional radar (SSR). Even Mode-S consists of several data formats, so called DF. Mainly we are just interested in DF-17 frames, but may use the other frame types as well. Now it happens that the aircrafts transmit their frames in a nearly uncoordinated way. There is some coordinaten by roll call, but this is done in each ground station radar antenna for itself.
The aircrafts do not check if the 1090MHz channel is free before starting their transmission. Due to this, frames may overlap each other, better say, they really do. See this little example:

Here we have 3 overlapping signals, there is a traditional SSR radar signal in the preamble of the weaker Mode-S signal and at the end a strong Mode-S signal starts

In radar world, all these unwanted signal overlaps are called FRUIT (abb. tbd). In transmission theory, it is called ALOHA effect, and it is limiting the channel throughput down to 18% of the possible channel capacity. In fact, when listening to Mode-S in high traffic times, I recognize a kind of a saturation when getting around 300 DF-11#/DF-17 frames.

One chance to overcome this problem is to implement a decoder that is capable of handling this. Since my decoder is designed for maximum sensitivity, it is not yet able to do so. I will add another decoder in the next firmware release that should be able to handle it. But yet this decoder is in the phase of an "idea".

Anyway, the better methode how to handle this problem is not even let it exist. We can easily split signals by using directional antennas. In this case the signals just then overlap if they are received by the same antenna. So if we spit up the 360° around a location into several segments

we limit FRUIT to just those signals coming from the same direction
we can use higher gain antennas because they can be made with directionality..

As shown here, each antenna is receiving a 90° wide sector. This is the maximum, but the priciple already works with two antennas, like shown by F5ANN, or three antennas.
Of course then it is possible to connect one even higher gain antenna towards a hot spot. There are many possible connections.

There is a very good design of a vertical segment antenna, actually designed for wireless LAN, but very useful for our purposes. The Amos-Antenna by YU1AW was already built by F5ANN for this purpose, and for Mode-S 1090MHz it is just 110cm high and 18cm wide, so quite a handsome piece.

NOTE: Who ever builds such a 4 antenna system for the first time gets a Mode-S Beast (3 miniADSBs for parts costs) for free. I can also support you with material.

The AMOS Antenna

you find all information here
http://www.qsl.net/yu1aw/amos_antennas.htm

There are standard AMOS and Inverted AMOS. In the documents you find also skaling information. From my opinion making the feed element from 2.5mm instead of 2mm is not a problem.

Once when I have done a rougth calculation, the height was 110cm and the width around 20cm. But there are several shown, several element number, so you might find something that fits better. Otherwise, the reflector is not necessarily a single piece. If you make a electrical joint, screw or rivet, each WL/10 (every 3cm), it is absolutely fine making it from several pieces.

The drawing on the right shows how I imaginge making them, the reflector plate is bent 90° along the long sides in order to get stability. The holders extend sideways because then you can mount 4 pieces around a single mast most easily. I am drawing just one element, but there are several, of course.