Satellite dish pointing indicator

In order to monitor the signal received by the antenna of the satellite system at its installation site, the device described below is very useful. It will allow you to accurately orient the antenna to the satellite and get good reception quality.

When installing equipment for receiving satellite television or the Internet, one of the problems is the exact orientation of the antenna to the satellite. It can be easily solved using the indicator, the appearance of which is shown in Fig. 1. It is equipped with a microammeter, the deviation of the arrow of which depends on the level of the received signal. The indicator is connected between the drop cable and the high-frequency irradiator-converter (the so-called LNB unit) of the satellite system.

The scheme of the device is shown in fig. 2. It contains two identical RF amplifiers on DA1, DA2 chips, a detector on a VT1 transistor and a voltage regulator on a DA3 chip. Each of the amplifiers consumes a current of 8...10 mA, has a gain of 22...25 dB up to a frequency of 2 GHz and an upper cutoff frequency of 2.5 GHz in terms of -3dB. The overall gain in the frequency range of 0.7 ... 2.2 GHz reaches 45 dB.

To suppress signals with a frequency of less than 700 MHz, a C2L2C3 high-pass filter is installed at the input. The sensitivity of the indicator is regulated by a variable resistor R10. The variable resistor R4 sets the DC mode of the transistor VT1, which serves as an amplitude detector. Power is supplied to the indicator via a drop cable from the receiver through the low-pass filter L1C1 and the protective diode VD1.

After connecting the drop cable and the converter to the sockets XW1, XW2 and turning on the device with a variable resistor R4, the operation of the transistor VT1 is set in such a way that the PA1 microammeter shows a current close to zero. The output signal of the converter (including noise) passes through the high-pass filter, the first, then the second RF amplifiers and enters the base of the transistor VT1.

With an increase in the amplitude of the RF signal, the collector current through the transistor VT1 increases, and the voltage across it decreases. As a result, a current will flow through the PA1 microammeter. The higher the signal level, the more the arrow deviates. With its small or large deviation, the sensitivity of the device is increased or decreased by a variable resistor R10, respectively.

With a slow change in the spatial orientation of the antenna and approaching the exact direction to the satellite, the indicator arrow deviates more. According to the maximum of its deviation, the antenna is oriented exactly to the satellite. In this case, the signal is sent to the receiver and you can observe the results of the settings on the TV or monitor screen.

In the device, in addition to those indicated in the diagram, you can use other small-sized parts for surface mounting: the INA03170 chip (DA1, DA2), any integrated voltage regulator in the SOT-89 package with a stabilization voltage of 8 ... 9 V (DA3), transistors - AT41411 , AT41435, AT41486 (VT1), fixed resistors RN1-12 of size 1206, variables of the SP4, SPO series, K10-17V capacitors or similar imported ones.

Coils L1, L2 are wound with wire PEV-2 0.2 on a mandrel with a diameter of 2 mm. Coil L1 contains 10 turns, winding - turn to turn, coil L2 - 3 turns with a step of 1 mm. Connectors - type F. Power switch - any small-sized. Microammeter - with total deflection current of 1OO...2OOmkA and resistance from several hundred ohms to several units of kiloohms.

Most of the parts are placed on a printed circuit board made of double-sided foil fiberglass, a sketch of which is shown in Fig. 3. The metallization of both sides is interconnected by a foil soldered along the edge of the board and through holes (by pieces of tinned wire). The board is soldered along the edges to the metal case cover, to which the connectors are also soldered, as seen in Fig. 4. Variable resistors, a microammeter and a switch are placed on the body (preferably also metal) of the device.

The current consumed by the indicator is approximately 30 mA. To power the indicator, as well as the converter, you can use an autonomous source, for example, a battery of galvanic cells or batteries with a voltage of 12 V. In this case, additional sockets for connecting the battery should be installed on the indicator case, connecting them to the terminals of the capacitor C1.

The updated measuring device Booox SF-01T (Ver.2.0) is designed for the most accurate tuning of digital terrestrial (DVB-T / T2) antennas, using a visual arrow scale synchronized with an audible buzzer. The device has high sensitivity to weak signals, and when receiving strong signals, you can use the sensitivity control.

First of all, it is intended for general users who do not have special measuring equipment at their disposal, but who want to independently install the on-air antenna correctly in order to save money. This device is very easy to use and suitable for all users (a handy instruction manual in Russian is attached to the device).

If you use this device, you will not regret it!

Suffice it to say that in most cases the direction of the antenna to the TV center does not coincide with the real direction of maximum power distribution (in relation to DVB-T2 channels). As the practice of alignment (correct orientation) of antennas shows, its deviation even by 10-15 degrees entails a decrease in the signal level by 3-8 dB, which is equivalent to installing not a long-range, but a balcony version of the antenna. Therefore, you spent money on an expensive antenna in vain and did not get the effect you needed !!! But your antenna should very confidently receive useful signals in all weather conditions at any time of the day and year!

Using the appliance

1. Passive antenna

The device, together with the LTE filter (see Fig. 1), is connected to the antenna drop cable (it is desirable that the length of the cable from the antenna to the device does not exceed 1-2 meters). The connection is carried out according to the available inscriptions on the device: "ANT" - antenna, "PWR" - battery pack (for rental conditions, 2 "Krona" batteries of 9 Volts are applied, which creates ease of use).

1. The connection diagram of the device is shown on If any amplifier is connected to the antenna, then it should be removed. The exception is the Rhombus active antenna (Fagor, Spain), because it works remarkably well in both active and passive (i.e. without power supply) modes. The LTE filter is used to exclude (suppress) possible interference to the input of the device from nearby cell towers (LTE) and allows you to very accurately align the antenna.
2. Make connections according to Fig.1. Connect an RG-6/SAT-703 class connecting cable (supplied complete with F-connectors already installed) from the antenna to the input connector of the LTE filter (the LTE filter itself is directly screwed onto the "ANT" connector on the device).
3. Connect the battery pack to the "PWR12-24 V" connector. When the power supply is connected, the backlight of the scale immediately flashes, which is very convenient in practice (power supply indication) when working at night (excellent visibility of the scale and arrow).
4. Direct the antenna in the intended direction of receiving DVB-T2 signals and using the sensitivity regulator (the knob is located under the "PWR12-24 V" connector), set the deviation of the reading arrow to about half the scale (4-5 divisions).
5. Slowly rotate the antenna in azimuth, achieving the maximum deviation of the instrument needle. If the arrow goes off scale (high signal level), then you should reduce the sensitivity of the device with the sensitivity regulator, returning the arrow to approximately the middle of the reference scale.
6. Continue tuning the antenna until the maximum deviation of the instrument pointer is reached. For a more accurate orientation of the receiving antenna, it is useful to change it and the elevation position (as a rule, slightly raising the conditional reception direction by 10-20 degrees upwards). It is most convenient to complete the final adjustment of the elevation position of the antenna by the maximum sound signal (the volume of the sound squeak of the device is proportional to the deviation of the device pointer).
7. Rigidly fix the antenna on the bracket or mast, following the indication of the device.
8. If a mast amplifier was used at your disposal (which was previously disconnected for proper setup), then it can now be returned to its original place.

2. Active antenna

1. The connection diagram of the device is shown in Fig. 1. The difference from the diagram in Fig. 1 is the connection of a directional coupler with a crosstalk attenuation of 15 dB, which makes it possible to attenuate the signal level supplied to the indicator device and at the same time provide a transit current to the amplifier built into the active antenna. A coupler (complete with a short connecting cable) with transit current is included in the scope of delivery.
2. When aligning the antenna, do not forget to supply voltage to your antenna according to your standard installation scheme for the receiving system (5 V or 12 V). The remaining steps for using the device are identical to subsection 1 (setting up a passive antenna).

Attention!

This device responds to obstacles near the antenna being tuned, so when tuning the antenna, do not stand in the direction of the antenna and do not point it at nearby obstacles (trees, walls, etc.). Tuning antennas indoors due to strong reflections from the walls with this device is impossible!

Key Features:

• The antenna is tuned to the maximum power of all received channels (DVB-T/T2).
• Very accurate tuning of the receiving antenna due to the presence of a sound signal.
• Light weight and small dimensions.
• Power supply via a drop cable along the central core or an external battery pack.
• Sound and visual indication of the received signal simultaneously.
• High sensitivity (the device works even with indoor antennas at very low electromagnetic field strengths).
• Easy operation and high reliability.

Contents of delivery:

Reliably align your antenna and you will reliably receive digital broadcasting regardless of weather conditions, season and time of day!!!

Happy viewing.

Often there is a need to make a simple check of the health of the RC transmitter, whether it and its antenna are working, whether the transmitter emits electromagnetic waves on the air. In this case, the simplest indicator of the electromagnetic field will be of great help. With it, you can check the operation of the output stage of any transmitter used in modeling in the range from several MHz to 2.5 GHz. They can also check the operation of a cell phone for transmission.

The device is based on a detector with voltage doubling on microwave diodes of the KD514 type of Soviet production. The principle of operation is clear from the circuit diagram. An antenna with a length of 20 ..... 25 cm is connected to the connection point of the diodes from a wire with a diameter of . 1.....2 mm. A filtering capacitor (tubular, ceramic) with a capacity of approximately 2200 pF is connected to the diodes. Diodes with a capacitor are soldered to the terminals of a microammeter, which is a device for indicating the presence of an electromagnetic field. The cathode of the right according to the diode scheme is soldered to the "+" terminal, and the anode of the left according to the diode scheme is soldered to the "-" terminal. The indicator antenna can be located at a distance from a few centimeters (2.4 GHz transmitter or cell phone) to 1 meter,
if the transmitter operates in the range of 27 ......... 40 MHz. Such transmitters have a telescopic antenna.
All details are located on a piece of textolite. The filter capacitor is located at the bottom of the scarf and is not visible in the photo.

circuit diagram

Photos.

A self-constructed antenna will only give good results when it is finely tuned and its parameters are measured with appropriate measuring instruments.

Antenna tuning basically consists of tuning the antenna in the appropriate frequency range, matching the output stage of the transmitter to the transmission line and matching the transmission line to the antenna, and finally, tuning the antenna to maximum radiation and, if possible, taking the antenna pattern.

For antennas powered by tuned transmission lines (provided that there are no gross errors in the dimensions of the transmission line), the measurement of the antenna resonance can be omitted. In this case, the communication device, usually placed at the beginning of the transmission line, allows you to tune the transmission line and the antenna to the operating frequency of the transmitter, and the tuning should be carried out until the maximum current in the antenna is obtained.

To measure the absolute value of the current in the antenna, you can use a thermocouple in combination with a sensitive device of the magnetoelectric system or a thermal device. However, such current meters are quite expensive and, moreover, very sensitive to overloads.

Usually, when tuning an antenna, a radio amateur does not need to know the exact value of the current, but it is quite enough when tuning an antenna to have a means to indicate its maximum.

In the simplest case, an incandescent lamp (for example, a scale illumination lamp) is switched on between the transmitter output and the transmission line, and the maximum current in the antenna is determined by its maximum glow (Fig. 14-1, a and b). A shunt resistance is connected in parallel with the incandescent bulb, preventing it from burning out.

On fig. 14-2 shows a simple and reliable device for indicating the maximum current in the antenna, which has the additional advantage that it consumes almost no power and yet serves as a fairly accurate indicator of the current in the antenna.

Shown in fig. 14-2 indicators of antenna current differ only in the type of connection with the transmission line. Any germanium diode can be used as a rectifier.

Sometimes it becomes necessary to have a high frequency voltage indicator. For this, a neon lamp is used, connected to the transmission line through a container, as shown in fig. 14-3.

A more sensitive circuit for measuring high frequency voltage with a germanium diode and a magnetoelectric system meter is shown in fig. 14-4.

The additional resistance R W depends on the internal resistance of the measuring device and on the desired sensitivity of the circuit. The capacitors used in the circuit are ceramic. In general, the use of diodes in the antenna circuit is undesirable, since when the high frequency voltage applied to it is rectified, higher harmonics arise due to the non-linear characteristic, which can enter the antenna and thus cause unwanted interference to television.

Antennas with tuned transmission lines can be tuned for maximum radiation using a transmission line tuning device (for example, a U-shaped filter) for the maximum current in the antenna. At the same time, the value of the maximum current itself does not determine the magnitude of the radiated power from the antenna: with current matching, the maximum can have a very large absolute value, and with voltage coupling, it can be very small, but the radiated power is the same in both cases.

If the antenna is powered by an untuned transmission line (matched line), then first of all, you should tune the antenna to the operating frequency of the transmitter and only after that proceed with matching the transmission line with the antenna. If this sequence is not observed in the antenna tuning, there will always be residual standing waves in the transmission line and an exact match will not be achieved.