In addition to the well-known and popular Mobilsat +, the Milanese Mobiltech has another automatic satellite antenna in its catalog, however, made with a project that starts from completely different technical assumptions than its older sister. This is the i-Sat, a model with a compact and modern design, which uses a Cassegrain type dish and which has the particularity of being able to be removed from the fixing plate and moved onto a tripod or other support surface. If our vehicle is parked under some trees with a refreshing shade, we will not have to give up satellite TV because it will be enough to move the antenna just enough to get an unobstructed view of the sky in the direction of the chosen satellite.
How does a Cassegrain dish differ from those normally used for itinerant satellite reception? The latter are generally of the offset type, therefore composed of a paraboloid reflector whose focus is not perpendicular to the axis of the paraboloid itself. In this case, the LNB is positioned on an arm that keeps it not in the center of the antenna but moved from it by a certain angle (offset, to be precise). Cassegrain type antennas, on the other hand, are of the prime-focus or primary focus genre, in which the illuminator is aligned with the focus of the dish; they also have a secondary reflector that focuses the signals towards the illuminator itself. This configuration is very compact, but if well designed it is quite performing and allows you to manage the satellite signal with a higher yield than an offset type of the same size.
At the New Car in Pomezia we were able to test the potential of the i-Sat and touch its technical and construction characteristics first hand. Opening the packaging, you immediately notice the small size: the base measures just over two palms and the space to be kept free for installation is contained in a diameter of 60 cm. The weight is no exception, with the balance needle that stops at 6 kg (like four bottles of water). With these assumptions, installation is extremely easy and it is not difficult to find a place for the i-Sat even on roofs that already accommodate various accessories. Due to the particularity of the Cassegrain system, the height of the closing antenna cannot be record-breaking, but the modern and sleek design makes the i-Sat seem even smaller than it already is.
Another avant-garde feature concerns the use, for the various connections, of a single RG 179 cable which, despite being of minimal size, at the same time transmits the signal to the decoder and powers the antenna. Therefore, by keeping aside a skein of this type of cable, equipped with a special connector, we can easily move the antenna. In fact, this is another of the peculiar characteristics that we have verified: the forward apex of the fixing plate meets a metal ear on the chassis and everything is stopped with a torx screw. Once the latter has been removed, just make a click counterclockwise to the antenna body, which is fixed with bayonet couplings to four hooks on the fixing plate, and everything is easily removed. At this point, having removed the connector of the RG 179 cable, you can place the i-Sat wherever you prefer, using any flat and stable surface or the specific optional tripod.
After the installation on the vehicle roof, we proceeded with the assembly of the control unit, which is also of minimal size and easy to manage. Like the Mobilsat +, in fact, the i-Sat also has the one touch function that allows you to activate the antenna and its automatic pointing by pressing a single button. There are seven in-memory satellites to choose from; if you are in an area on the periphery of the reception footprint, you can perform a manual scan, for a more detailed location.
This modern antenna is supplied on request as a kit with a TV-Sat decoder for DVTB broadcasts, but can be combined with any type of satellite decoder on the market. Having said that, and an LCD TV installed on board, we arrived at the highlight of the reception test, which we carried out by positioning the i-Sat both on the roof of the camper and on a trolley at a certain distance from the vehicle. Considering the small size of the dish (equivalent to a 60 cm offset), the satellite capture was rather quick and precise in both cases.
Basically, the i-Sat Mobiltech antenna (distributed by St.La.) seemed to us an interesting and highly versatile product. Although very small in size, it combines various functions typical of larger antennas, it is very easy to use and easily captures the signal coming from the satellite, with a truly negligible power consumption. Obviously, while enjoying a Cassegrain type dish, we must not forget that it is still 40 cm in diameter, which does not in any way affect the quality of reception if we remain in continental Europe, but which could require an adjustment of the skew if we were to the limits of the footprint. This operation is not complicated and requires only a minimum of tinkering with simple tools. Furthermore, considering that it is a fully automatic product that uses precision mechanics that work on self-lubricating bearings, a very interesting quality-price ratio is observed.
In conclusion, those who have problems of space or weight on the roof of the vehicle but do not want to give up quality, watching television even in the shade of some big tree or under the shelter of a canopy, can certainly rely on the characteristics of this modern accessory.
Giovanni Battista Bertolani
