Log-periodic antennas belong to the class of directional devices. Models, as a rule, work on short waves. Most devices are equipped with a highly conductive reflector. Some modifications are made with a panel vibrator. They have one or more amplifiers. It should also be noted that there are devices with channel transmitters.
What are the main parameters of log-periodic antennas? First of all, it is important to consider the frequency of devices. Also, specialists consider the directivity and gain. The input impedance also affects the parameters of the antenna.
Calculation of the model
The antenna is calculated based on the length of the rack. If we consider models with one vibrator, then the reflector is of the dipole type. With a length of 20 cm, the width of the panel should be 30 cm. When increasing the size of the rack, the panel is selected with the appropriate dimensions.
DIY device
Do-it-yourself log-periodic antenna is folded with a simple reflector, and it is more expedient to use a vibrator with an extension cord. First of all, the mast is placed directly. Racks are fixed with a welding machine. Experts advise to immediately install the amplifier.
Wiring should only be used with grounding. Different types of expanders are used to reduce the frequency. Most models work from contact adapters. Upper racks should be used with a small diameter. It is also necessary to pay attention to the lower adapter from which the wire departs. Depending on the calculation of the model, the dimensions of the log-periodic antennas depend.
Model for a simple receiver
Logo-periodic antennas for simple receivers are made with small masts. The most common modifications are considered to be three racks. If we consider an antenna with one adapter, then the reflector is used with a capacitor. It should also be noted that the mast is fixed on the rack. The horn in this case is very rare. Adapters at the antenna are attached through the holders. Experts say that models with dipole adapters are considered the most popular. They can operate on shortwave.
Single Stand Unit
Single pole antenna is not highly conductive. There are devices with reverse vibrators on the market. They have a fairly wide base. In this case, the holders are installed with a small width. If we consider a standard log-periodic antenna, it has one reflector. Racks are established on a fixing support. Antennas are often sold withoutholders. They have a stand with a wide base. The highest quality is considered to be devices with reinforced adapters. Vibrators can also be installed without an adapter. Racks in this case are of small length.
Two Post Model
A log-periodic UHF antenna with two racks is made with a reflector for three channels. Experts say that the models have different conductivity. When choosing a modification, one should pay attention to the support of the modification. Holders can be installed L-shaped. Quite often, antennas of this type are installed on the roof.
Devices are well suited for receiving a TV channel. However, they are not capable of operating at all frequencies. In this case, much depends on the shape of the reflector. Modern modifications of log-periodic antennas are used with output amplifiers. Only open adapters are installed under them. In this case, the vibrators are mounted in the central part of the rack. Masts vary in length. A lot depends on the width of the racks. The conductivity of the modification depends on the reflector. The wire from the antenna must come off the expander.
Horizontal antennas
The horizontal log-periodic type TV antenna stands out with a wide stand. Many models use a long mast, and the supports are made only of aluminum alloy. If desired, such an antenna of a log-periodic type can be made independently. It is well suited for a receiver of low power. Experts say that the firstthe holder is queued. Only then can the mast be installed. The next step is a reflector. If we consider store modifications, they have two vibrators.
Most models are made without stops. Racks are in a horizontal position. To install a log-periodic antenna, wide metal fasteners are used. It should also be noted that there are high-frequency modifications in which an amplifier is installed. Expanders for devices are selected only for high conductivity. Quite often on the market there are devices with negative polarity. First of all, experts note that they have no problems with short waves, and a very high gain. The dimensions of log-periodic antennas directly depend on the model calculations.
Vertical modifications
Vertical log-periodic antenna is often found in shops. The calculation of the model is carried out based on the dimensions of the rack. Log-periodic vertical antennas are produced with reflectors of different conductivity. Most models are made on contact adapters.
Also in stores you can find devices without amplifiers. As a rule, they use short reflectors, and the vibrators are installed of the short-wave type. The minimum allowable antenna frequency depends on many factors. In this case, the user must take into account the resistance of the reflector. Additionally, you need to know the type of expander. Most models are sold with regular controllers.
144 MHz device
Logo-periodic antennas of this type are made with long racks, and vibrators are used with supports. The standard model includes one connector. Amplifiers for these log-periodic antennas are installed with different powers. Additionally, it is important to remember that modifications differ in conductivity. Some devices are made with one rack. They have low input impedance. As a rule, they are produced with an output vibrator. The holders are installed at a low height. If desired, such an antenna of a log-periodic type can be made by anyone. In this case, it is important to calculate the height of the rack.
Modification to 145 MHz
Antenna for TV of this type is made only with a dipole reflector. In this case, vibrators are used with medium conductivity. Experts say that modifications with wired adapters are quite common on the market. Their reflectors are mounted on racks. Side supports can be very large. Also noteworthy is the high resistance level of these log-periodic antennas.
If desired, the model can be assembled at home. For this, specialists use metal racks that are interconnected using a welding inverter. The vibrator is used with one output. The wire from the antenna is fixed on the expander. As a rule, it is mounted at the bottom of the mast.
Model with copper mast
Logo-periodic antenna for T2 with coppermast works great at different frequencies. The standard model includes a contact adapter that snaps into place at the bottom of the stand. Vibrators for models are used only with an expander. It should also be noted that there are antennas with wide reflectors in stores. Most of them can work at low frequencies. Experts say that there are reverse polarization devices. For them, expanders are used with contact reflectors. Some models are equipped with amplifiers that connect to subs.
Devices with steel mast
Logo-periodic antennas with a steel mast can be made by yourself. For this, experts recommend preparing wide supports. Most models are highly conductive and are well suited for signal reception. Vibrators for models are used with different sensitivities. In this case, amplifiers are usually installed at the bottom of the masts. Experts say that the adapter must be fixed only through the transistor and the power supply.
Additionally, it is important to note that when assembling the model, problems may arise precisely with the racks. If we consider store antennas, then they have a wide holder. In this case, the front supports are securely fixed directly on the mast of the device.
