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The topic of this article is inspired by the Delta H311-01A antenna (active with an amplifier) received for repair. The design of the antenna is such that if you remove the vibrators to receive the meter range (which will significantly reduce its dimensions), then it can only be used as an antenna for the decimeter range.
Delta H311-01A is a version of the Delta 311-01 antenna without an amplifier. All-wave TV antenna, with a broadband amplifier, is used in conditions of poor reception in the MW and UHF bands. Receives signals of analog and digital TV broadcasting, in the frequency range 48.5-890 MHz and consisting of decimeter antenna and a vibrator of the meter range. The antenna has a uniform gain over the entire frequency range.
The antenna design is quite simple and therefore it is quite accessible for repetition. The main elements of which the antenna consists are: decimeter part; vibrator MV; matching board and signal amplifier. The complex elements include: a matching board and an amplifier, but you can do without them by installing a SWA type amplifier.
The decimeter part is a log-periodic antenna with 20 vibrators.
A log-periodic antenna (LPA) consists of two pipes located one above the other, to which the arms of the vibrators are attached alternately through one.
The cable is connected to the LPA without a special matching device as follows. A 75 ohm cable is inserted into the bottom pipe at one end and exits at the other. The braid of the cable is soldered to the end of the lower pipe and the center conductor to the end of the upper pipe.
Depending on the wavelength of the received signal, several vibrators are excited in the antenna structure, the dimensions of which are closest to half the signal wavelength. At a given signal wavelength, only one triple of vibrators is excited, and the rest are out of tune and do not affect the operation of the antenna. The antenna gain drops slightly, but the bandwidth is much wider.
It is useful to know that the smoother the surface of the conductors from which the antenna is made, the higher its quality indicators (higher quality factor).
The MV range antenna is designed very simply - these are two vibrators 110 cm long, attached to the protective case of the amplifier.
The matching board and amplifier are hidden in a sealed case.
The balun is used to match VHF and UHF antennas with an amplifier.
Dimensions (edit)
For those who want to make a copy, here are the dimensions. UHF antennas and MV.
All antenna dimensions are in millimeters. The diameter of the tubes is 12 mm, the diameter of the vibrators is 4 mm, the size of the gap between the tubes is 6 mm. At the beginning of the antenna, the tubes are fixed with plastic; at the point of attachment to the mast, the tubes are soldered.
The antenna gain can be further increased by adding a reflector behind the antenna mount.
Among radio amateurs, a loop antenna with a perimeter of 84M is very popular. It is generally tuned to the 80M band and with little compromise it can be used on all amateur bands. Such a compromise can be accepted if we work with a tube power amplifier, but if we have a more modern transceiver, it will not work there. We need a matching device that sets the SWR on each band corresponding to normal work transceiver. HA5AG told me about a simple matching device and sent me a short description (see picture). The device is designed for loop antennas almost any shape (delta, square, trapezoid, etc.)Matching device HA5AG
Click on the diagram to enlarge
Short description:
The author tested the matching device on an antenna, the shape of which is almost square, installed at a height of 13M in horizontal position... The input impedance of this QUAD antenna on the 80M range is 85 Ohm, and on harmonics 150 - 180 Ohm. The characteristic impedance of the supply cable is 50 Ohm. The task was to match this cable with the antenna input impedance of 85 - 180 Ohm. For matching, a transformer Tr1 and a coil L1 were used.
In the 80M range, using the P1 relay, short-circuit the n3 coil. In the cable circuit, the n2 coil remains switched on, which, with its inductance, sets the antenna input impedance to 50 Ohm. On other bands, P1 is disabled. Coils n2 + n3 (6 turns) are included in the cable circuit and the antenna matches 180Ω to 50Ω.
L1 is an extension coil. It will find its use on the 30M band. The point is that the third harmonic of the 80M range does not coincide with the permitted frequency range of the 30M range. (3 x 3600KHz = 10800KHz). The T1 transformer will match the antenna at 10500KHz, but this is still not enough, you need to turn on the L1 coil and in this turn on the antenna will already resonate at a frequency of 10100KHz. To do this, using K1, turn on the P2 relay, which at the same time opens its normally closed contacts... L1 can also serve in the 80M range when we want to work in the telegraph section. On the 80M band, the antenna resonance band is about 120KHz. To shift the resonance frequency, you can turn on L1. The switched on L1 coil noticeably reduces the SWR at 24MHz frequency, as well as at 10M range.
The matching device has three functions:
1. Provides symmetrical power supply to the antenna, since the antenna web is isolated by HF from "ground" through the transformer coils Tr1 and L1.
2. Matches the impedance described higher way.
3. With the help of coils n2 and n3 of the transformer Tr1 puts the resonance of the antenna in the appropriate, allowed frequency bands across the ranges. About this in a little more detail: If the antenna is initially tuned to a frequency of 3600 kHz (without turning on the matching device), then on the 40M ohm band it will resonate at 7200KHz, on the 20M band at 14400KHz, and on the 10M band already at 28800KHz. This means that the antenna must be lengthened in each range, and at the same time higher frequency range, the more lengthening is required. Now, just such a coincidence is used to match the antenna. The coils of the transformer n2 and n3, T1 with a certain inductance, the more the antenna lengthens, the higher the frequency of the range. In this way, on the 40M band, the coils are lengthened to a very small extent, and on the 10M band already to a large extent. A correctly tuned antenna is put into resonance by the matching device on each band in the region of the first 100KHz frequency.
Positions of switches K1 and K2 by ranges are shown in the table:
If the input impedance of the antenna on the 80M range is set not within 80 - 90 Ohm, but within 100 - 120 Ohm, then the number of turns of the coil n2 of the transformer T1 must be increased by 3, and if the resistance is even more so by 4. The parameters of the remaining coils remain unchanged ...
Photo: Matching device HA5AG
Click on the photo to enlarge
73! de HA5AG
Translation: UT1DA
source - (http://ut1da.narod.ru)
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Networks are now widespread wireless access to the Internet of the 3G generation. If in the city special problems if there is no signal reception, then outside the city (at the dacha), it is far from always possible to get a high-speed, stable connection. To increase the efficiency of reception, manufacturers produce various equipment, - antennas, repeaters, etc.
After communicating with users, some difficulties emerged when installing antennas outside the city, up to the impossibility of determining the base station to which the antenna must be tuned. Our experts decided to carry out the customization and develop a methodology and recommendations for ordinary users. The tuning was carried out in the village. Naziya (station Zhikharevo) of Kirovsky district Leningrad region... The equipment used was an MTS modem E171, a TOSHIBA laptop (Satellite M20) and an APS antenna Delta 16 / 1800-2170 (manufactured by NPP OST CJSC) with a Delta 1.8-2.17 adapter
Antenna brief description: 16-element wave channel with vertical polarization, Ku - from 12.5 to 16 dB, operating frequency band 1800-2170 MHz, VSWR no more than 1.5, KZD - 12 dB, completed with a 9.4 m RG58U cable with FME socket. Adapter - fractal irradiator with a bandwidth of 1800-2170 MHz with an FME plug. At the test site, a modem was activated to determine the signal strength in the house and the data rate without increasing the antenna reception efficiency. The testing site 2ip.ru was used to measure the download speed. The result is a signal level of 30-40%, the download speed in 3G is 200-500 kbps.
By placing on open area laptop and antenna, there was an attempt to locate base station MTS. By turning the antenna, we achieved the most effective reception, controlling it by the signal level indicator in the MDMA program.
As it turned out, the transmission tower of the MTS was not at all where it was supposed earlier. We installed the antenna on the mast and tuned it to the tower, knowing its preliminary location. As a result, we came into direct visibility of the tower, it turned out to be about 5 km to it. The height of the antenna's suspension above the ground was about 10 m. The drop cable was lowered into the house and connected to a laptop. The signal level has clearly "stood up" 100%. When measuring, we got the incoming connection speed from 3.7 Mbit / s to 4.1 Mbit / s. This speed allows you to watch movies online in decent quality without any "braking". To check, they disconnected the antenna from the modem and measured the speed several times, got 164-200 kbps.
As it turned out, the use of the antenna improves the reception quality of the modem several times.
If the 3G modem has a slot for external antenna CRC9 or TS9, it is better to use a CRC9-FME or TS9-FME adapter. Advantage this connection is to minimize signal loss when connecting a modem to an antenna, compared to a wireless connection.
V. DAVYDOV (UW9WR), Ufa The disadvantage of the previously described electronic switches antennas is a significant attenuation in the receive mode, reaching 45-50% (especially in the 21 and 28 MHz bands). Switch, scheme which is shown in the figure, provides an attenuation of no more than 10%. When manufacturing the switch, it is necessary to isolate the case of the output capacitor of the P-circuit (in the diagram - C4) from the chassis with a fluoroplastic or polystyrene gasket 5 mm thick. The antenna is connected to the Gn1 socket, the receiver input to socket GN2.RADIO No. 7, 1975 p.15 ...
For the "MINIATURE DIRECTIONAL ANTENNA FOR THE RANGE 144-146 MHZ"
For the scheme "ALL-METAL DELTA-ANTENNA"
For the diagram "Double square antenna design"
For the scheme "DUAL-WAY ANTENNA UHF"
For the "VERTICAL ANTENNA AT 144 MHz"
For the diagram "Antenna amplifier for radio transmitter"
RF power amplifiers Antenna amplifier for radio transmitter Scheme antenna amplifier does not require special explanation. The amplifier is mounted in a 1 mm thick galvanized metal casing, dimensions - 120x60x30 mm. An aluminum plate of the same size, 10 mm thick, is screwed to the bottom of the body. Design printed circuit board the same as in [З]. The drawing is not shown here, because the configuration of the board is highly dependent on the type of parts used. It is only important that all connections are as short as possible and that a reliable thermal contact of the transistor VT1 with the radiator plate is ensured. Details Relay K1, K2 - RES-15 (002). Connectors XW1, XW2 - CP-50-73F. Resistors - MLT. Capacitors - KT, KM; S16.C17- KPK-MP. Inductors: LI - choke DPMZ-3 10 μH; L2 - 14 turns on a resistor MLT-0.5 150 Ohm PEV-2 0.35 turn to turn. L9, L11 -DPM1-0.1 56 μH. The rest of the coils are frameless, wound with a PEV-2 0.8 wire on a 5.5 mm mandrel. The number of turns depending on the range is shown in the table. In the same table, capacitances SZ ... C15 (pF) are indicated. Range L3L4L516L718L1C3X4X5X7X8X9X10X11X12X14X1527. ..29 MHz346999856047011068470200 ... 27027027011Q682750 Hz23577763302706839270120 ... 150150150683915 The tuning of the antenna unit is contained in the tuning using C16, C17 of the input circuit of the antenna amplifier according to the maximum sensitivity of the radio station receiver. By connecting an RF generator to input A5 ...
