CODE DESCRIPTION
DL
2595
ANTENNA TRAINER – didactic equipment
The trainer must be designed to introduce students to the comprehension of the antennas operation mode.
The trainer must include:
1. Basic Panel with generator, Lecher line, RF detector
2. Mobile receiver
3. Joint for fixing to the base
4. Supporting base for receiver
5. Reflector
6. Locking knob
7. Shielded connecting cable between the Lecher line and the detector with banana plugs, diam. 2 mm (length = 60 cm)
8. Set of cables for measuring and connections
9. Coaxial support for antenna (mast) with turning base
10. ‘T’BNC
11. Set of 5 monopoles with banana terminations, different lengths
12. Ground-plane antenna
13. Yagi antenna
14. Folded dipole antenna
15. Simple dipole antenna
16. Coaxial cable RG59 with F/F BNC, length = 60 cm complete of M/M and F/F adapters.
Frequency: from 860 to 950 MHz.
Power supply: - 15 Vdc, 200 mA
The basic unit must be composed of a base in varnished aluminium containing the RF generator, the Lecher line and the RF detector/meter.
The generator frequency must be between 860 and 950 MHz, higher than the band used for the TV broadcast and lower than the
frequencies used for the cellular radio transmissions. Any-how, the power of the transmitter must be such that no disturbances to the two
above mentioned systems are possible.
The choice of a frequency in this field must be determined by the possibility to reduce the dimensions of the antennas, hence to use the
trainer indoor, in a school laboratory.
The generator must be provided with a manual control of the output power, with graduated scale from 0 to 100 %. The generator output
must be a BNC mounted on the front of the panel, centered to a graduated disk.
On the BNC must be directly inserted the support for the power supply of the antennas, while the graduated disk shall be used for orienting
the antenna with respect to an initial reference point, as required during the experiments.
The generator must be designed with particular criteria in order to operate in potentially difficult conditions that can be found in a school
laboratory: it shall operate with no damage with large load variations, antennas with very different characteristic impedances, or even
without load.
The generator must be provided with two settings which shall be regulated by removing the metal lower side of the panel. The two settings
must be identified by the letters U and F. F must be a capacitive trimmer which shall determine the working frequency of the oscillator; U
QTY
must be a second trimmer which shall determine the working load impedence interval of the generator.
In other words, It must maximize the output power for a given load.
The Lecher line must be a transmission line with cylindrical parallel conductors in air, length about 36 cm.
One terminal of the line shall be connected to the generator output through the coaxial cable (included).
The Lecher line must be different from a standard line because it shall be provided with a cursor composed of a coil which, from the
transmission point of view, shall be considered a mobile short circuit.
The position of the cursor with respect to the origin must determine the length of the short circuited line and this system must allow the
measurement of the generator frequency, the study of the stationary waves along the line and the possibility to perform other experiments
concerning the adaptation of the antennas to the load.
On the same basic panel must be mounted the RF detector/meter to be coupled with the Lecher line cursor through the two wire cable
(included).
The RF detector must be composed of: a real detector at maximum value, an attenuator controlled by a knob in the front panel with
graduated scale from 0 to 100 % (100% = maximum attenuation, i.e. minimum signal), and a linear scale micro ammeter.
The trainer shall include also a radiation mobile detector composed of a plastic case with a folded pole, with adjustable reflector.
The front must include a pointer instrument for the indication of the received signal intensity, an attenuator which shall allow the adjustment
of the scale of the instrument and two output bushes to which to connect external instrumentation (if needed).
The instrument shall be held in one hand or mounted on the given support. In the latter case it shall be mounted vertically (so that the
dipole shall be on a horizontal plane), or turned by 90° in order to operate with the antennas with vertical polarization.
The trainer must be composed also of a series of antennas, some of which are made of mobile components so that it shall be possible to
create different configurations.
With this trainer it must be possible to perform the following experiments:
•
The Lecher line
•
Polarization
•
The elementary dipole
•
The folded dipole
•
The Yagi antenna
•
The ground plane antenna
•
The matching stub
The trainer must be supplied with relevant manual in English language.