The owner of CB radio when installing the antenna on the roof of the house, not only spends that is a significant amount, sometimes comparable to the cost of the station, but also listens to the complaints of many, not always friendly people. In some extent, the issues here are off of a balcony antenna "boomerang". But there is another way: below described construction is simple to manufacture full size CB antenna, so-called "Polany" set on the window of the apartment.

As an antenna it is recommended to use telescopic fiberglass the bait, which is fixed to a segment of flexible wire. An example of placing such the antenna shown in Fig. 1.

CB antenna on the window

Fasten the bait on the box in different ways. One option attachment depicted in Fig. 2. Here: 1 - sliding glass-plastic rod length 6 m; 2 - thrust bearing (Fig. 2, b), attached to the vertical post window frames; 3 - hard or soft sling that secures the antenna in the desired position; 4 - vibrator length 5,24 m, made of wire type or MAR Mgshv scenium of 0.2...1 mm2, 5 - matching device in the waterproof case; 6 - coaxial cable brand RK50-2-16; 7 - 5-10 ferrite rings (permeability 50...2000) over coaxial cable.

Schematic diagram of the matching device, the step-down high active resistance "Polany" to 50 Ohms as shown in Fig. 3,and. Coil L1 Is frameless, wound on a mandrel of diameter 8 mm wire sew-2 to 1.5.The number of turns - 9, the winding length of 19 mm. Capacitors - type CSR-1.

The matching device is assembled on the PCB of unilateral foil fiberglass 2 mm thick (Fig. 3,b ). It's placed in protective cover made from high impact polystyrene (Fig. 3, in).

The vibrator is laid along the rod, locking it at the end of each tribe with electrical tape. In the window casing and the window sash round file diameter 4...5 mm make the mating notches for the passage of the coaxial cable. It allows, setting the antenna firmly to lock the window.

The antenna set up in the usual way: clenching-unclenching the turns of the coil L1, achieve minimum SWR in the middle of the range of operating frequencies. To achieve the CWS equal to 1, it may be necessary, in very small range (2...3%) change the length of the vibrator and / or the capacitance of the capacitor C2.

As experience has shown, the antenna is not inferior to "range" full-size "The boomerang". Strip its operating frequency (VSWR less than 1.5) - 300-400 kHz.

Author: Yu. Vinogradov, Moscow

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