ANTENNA QUAD 2.4 GHz, 1.2 GHz and UHF-TV.
One antenna (panel or punt) quad (mono, Bi, quadruple, multi etc.) is especially employed for the applications in ISM, 2,4 GHz, (also in 2,3 GHz, 1,2 GHz and 433 MHz, radioamateurism), mainly used by Wifi or professional and domestic video surveillance (ex: camera embarked for model making).
One can also use it to collect the signals of , in the zones with sufficient field, but with the dimensions adapted to .
In 2.4 GHz, it quad is made of a curtain comprising only one (rare) or generally of two or four quadrilaterals (copper from 1 to 2 mm) of 31 side mm, placed at 15/22 mm (to be determined in experiments) of reflectors in full aspect, metal plate, or openwork, netting, having indicative dimensions, of 10 X 10 cm (or disc of 13 cm) or of 21 X 10 cm.
Connection to the center of the curtain is done either directly on the coaxial one length strictly necessary, (advised to have a minimum of loss) or via a standard card base "N" or "SMA" connected to one coaxial of impedance 50 ohms or with a card "F" for cable 75 ohms.
Nb: attention certain connectors, cards, or bottom-of-the-range connections introduce losses being able to reach 2 dB.
Profit, to 2.45 GHz, isotropic or absolute, this type of antenna approaches 12 (2 cells) or 15 dBi (4 cells). The realization is not difficult (means, precision, materials etc.). In the version quadriquad the single circuit transposition of copper is dénivellé (space of approximately 2 mm).
By its more marked directivity, quadriquad produce a much better result than it known as "ricoré", well-known of the wifists and competition still itantenna horn-funnel. The quads can also made of 2 or 4 circular loops (perimeter of a loop 12.3cm).
The informed amateurs manufacture rectangular sextuquads, or octoquads (8 cells) carrying the profit with nearly 18 dBi, for a square surface of the order 23 cm on side. To profit from this profit with a parabola let us note that its diamétre would be close to 43 cm.
These antennas quadrilatères "house" function just as easily that the manufactured goods, often much more expensive..
In version 1.2 Ghz biquad the length on a side is worth 62 mm and space between the curtain and the reflectors, 24x20cm, is also to refine in experiments.
In Wi-Fi, and in a preoccupation with a sought discretion, this antenna punt being able to be hooded can be preferable with an Yagi aerial or propeller more visible and emcombrantes. The antenna panel with technology quad should not be confused withantenna patch more current, but also more delicate to study and build for a private individual. Let us note that quad and patch with 4 elements bring the same profit appreciably as a parabola of about 30 cm.
The antennas with technology quad, easily conceivable, are thus most powerful compared to their obstruction, only the patchs are a little more discrete, the horn being located ahead last position, the parabola being bulkiest with equivalent profit.
For the bands of television UHF, and analogy Secam and , the antenna biquad (or double quad) and quadriquad is built on the basis of side of 12 cm (centered average value) but if the frequency band is rather low 14 cm is rather high 10 cm. Élement the quad can be built with threaded rod or tube of 4 mm.
The reflectors is done with a metal netting with meshs in contact of 3.5 cm. The distance séprant the quad with the back panel is determined in experiments, around 10 cm, to adjust. Dimensions of the reflectors dish, which can also be full, are variable overflowing in the direction of the width of a few centimetres. The obstruction vertical of the antenna UHF quad depends on the number from stages, 1, 2 or 4. This fact a panel of 90 cm X 45 cm is possible.
The profit of the biquad is about 8 dB and 11 dB in quadriquad
Made quad TNT oneself can be installed in the attic and with the exterior but there by adapting it to the particular conditions, ex to insert it in a plastic box.
Reception inside the buildings
The antenna technology biquad, in form from "8", is also known under " butterfly "in the antennas known as of interior or apartment. These antennas are often followed of an electronic part of amplification (or amplifier with profit variable by potentiometer) and supplemented of one or two telescopic bits for the band VHF I, II and III. The operation as of the these antennas of interior is often random in the difficult zones and field heterogeneous.
Easy way: Near transmitters TNT-TAT, therefore in rather strong field, it is enough to take a standard coaxial cable, adapted length, to build an antenna of the type groups channels UHF, a quizaine consecutive, but which can exploit +/- bands IV and V.
One separates, strips, the heart of the braid on 24 cm (+/- 4 cm), then one joins together these 2 ends in order to form a square framework. The plan of this last is placed perpendicularly with the axis of the radiation. You have an adapted antenna monoquad now, with optimum profit for this type of modest realization, but which profits from essential qualities of resonance.