Saturday, September 28, 2013

Matching the supply line to the antenna output of transmitter

The figures below show matching circuit transmitter output stage and power supply line connected to the antenna. Some of these schemes are seldom used because they have a weak filtering harmonics . Figure a) shows a matching circuit in which the antenna is connected directly to the output circuit of the transmitter. Matching is done by changing the capacitor C1, or change the point of connection to the antenna circuit ( change in the number of turns ) . As an indicator that will show the output matching circuit and antenna can be applied ammeter or a neon bulb. But the maximum ammeter or glow lamps can not always talk about the good coordination of the system. The current can reach its peak in the event of a standing wave in the supply line and the devices may not be current at the antinodes . This situation can occur when a wire is broken antenna SWR and has an infinite value . The following diagrams b) and c) are diagrams in which approval is best filtering harmonics of the transmitter. But because of the presence of inductive coupling between the coils L1 and L2 in the antenna section of the inductive reactance , an additional character. Sometimes when a large inductive coupling between the coils L1 and L2 can occur a substantial redistribution of the currents in the power supply line and the antenna. In order to compensate for the inductive coupling between the coils can be applied capacitance C3 - Figure d). But in this case, the circuit is interrupted by the DC that prevents run-off from the antenna electrostatic discharges. In the figure e) shows the matching circuit and the power line transmitter output stage transistor . Then use the usual resonance system , increasing resistance and the degree of transformation is the selection of the capacitors C1 and C2. In the VHF band can apply an agreement in Figure f). In order to reduce the level of higher harmonics can apply a Faraday shield (all circuits except a)). As this screen, you can use the shell coaxial cable - figure h). This screen can be used when a particularly high level of harmonics . Loop cable is closer to the edge of the grounded coil output stage . Even more harmonic filtering can be applied if the agreement scheme on the image i). In this circuit, an antenna circuit is divided by filtering and matching circuit . As the coil connection can be used here as a coaxial cable as shown in the previous figures . Circuit performing the role of filtering and matching can be taken away from the transmitter output stage and place them in a more convenient location and the connection between these stages can be performed from any piece of cable with a characteristic impedance . Loss in this case is extremely small and can be neglected . The circuit in Figure i) is called a filter Collins.

Thursday, September 26, 2013

Amateur G5RV wire antenna

Amateur G5RV wire antenna in the picture with a size of 31 meters, it is the transition between the antenna option with long arms and a 54-meter antenna with an arm length of 27 meters. By wire antenna connected two-wire power supply with an impedance of 300 ohms (balun). Length of the power line should be 12.90 meters. This line acts as a power transformer. Towards the bottom of the feed point of the transformer is connected coaxial cable (Figure).

In the range of 28 MHz each half G5RV wire antenna has a length 3L / 2. Diagram of a shape of the antenna length 3L. In-phase excitation power gain compared to a conventional dipole is 1.8. In this range, the antenna G5RV works well. Since the length of the line is transforming 5L / 4, the wire antenna is in excellent agreement with the coaxial cable. At the points of "BB" impedance of about 60 ohms.

In the range of 21 MHz antenna length is slightly longer wavelength (L) of the range and reach the transformer is also a little longer than 3L / 4 matching any worse. Sizes do not allow you to work in a resonant mode, in spite of this antenna has a gain over a dipole is 1.8 dB, due to the fact that half the vibrator excited in phase. Diagram of the wire antenna in the same range as the two wave vibrator.

In the range of 14 MHz antenna matching is even worse than 21 MHz. At the points of "AA" very little resistance from the fact that the antenna has a size of 1.5L and is approximately 70 ohms. At these points there is a maximum current. Transforming line transforms the antenna impedance (70 ohms) to 200 ohms at points "BB". It is clear that such resistance is not suitable for connecting a coaxial cable with an impedance of 50 ohms ... 75. Reinforcement wire antenna in the range of about 2 - 2.2 dB.

In the range of 7 MHz G5RV wire antenna has a length 3L / 4 and the input impedance of 600 ohms. Length of transforming the line has 300 ohms resistance and the length of the 0.3L, as a result of the partial transformation of the 600 ohm resistance at the points of "AA" to the point "BB" is obtained impedance 150 ohm. Since the directional properties of the antenna wire in this range are similar pattern in a half-wave dipole and the win is no gain.

In the range of 3.6 MHz is a resonance antenna of its length in this range is 0.36 ... 0.47L. Antenna impedance is 150 ohms, the length of the transformer is equal to 0.15 ... 0.16L at points "BB" resistance is 100 ohm. In this range, the directional properties of even worse and the winning wire antenna gain, however.

From the above it follows that the written wire antenna (classical) English G5RV amateur radio should be used in conjunction with the tuner (for the transceiver). Changing the length of the line transformer and its impedance leads to improved coordination in some ranges and a deterioration in others.

wire antenna g5rv

wire antenna g5rv

A Practical Antenna for 160 Metres


Antenna for 160 meters band

Original article published by G3YCC

"This aerial is one I have used for top band (160 metres) - it was suggested to me by Alan G4ERZ, also of Hull.

It consists of 140 feet of insulated wire, the first half of which (70 feet) is space wound on an insulated tube.

  • I used glass fibre tubing which was to hand, but PVC may be used also.
  • My tube is 1 1/2 inches in diameter and about 5 feet 6 inches long.
  • The turns are about 0.5 inches apart.
  • The other 70 feet of wire acts as a loading wire and slope down from the top of the coil to near ground level.
  • The system is coax fed to the base of the coil, with the shield or braiding going to earth.

It appears to work very well, apparently giving some horizontal and vertical polarisation.

One great advantage is the system can be tuned without having to lower the mast - by pruning the loading wire to resonate on the required part of the band.

Bandwidth is also good - mine is about 30 kHz either side of resonance.

I found the MFJ Antenna Analyzer MFJ-259 invaluable for this project, as well as many other experimental systems. Ensuring an efficient earth system will add to the effectiveness of the aerial I still have to improve my earth system, currently it consists of two 140 ft radials and connections to some buried guys stays.

Alan, G4ERZ, has a far more elaborate and efficient ground and his results prove what we all know - the ground (or earth system) is all important. He is a tremendous signal on 160 DX wise. He still gets the same band width as I do, though. I have worked a few DX stations with it since erecting it only a short while ago, and I think it has a lot to offer, especially for those of us blessed with relatively small gardens."

A short dipole for 80 meters


The antenna above has been described by Nadisha, 4S7NR and may be of interest to anyone wishing to get on 80M (3.5MHz) that have limited space available.


L1 is 12 feet. L2 also is 12 feet and the overall length is 48 feet.

The two loading coils are described as 67.83uH and can consist of 104 turns of insulated wire, wound over 3.5 inches. The coil diameter is not stated however. Maybe it will be a case for experimentation here.

An Inverted L for stealth with low(ish) visual impact

With a small back garden there is no way that I could accommodate an aerial for the 160m band that would be anything approaching full size. A full size dipole would be about 65 metres long and would need to be mounted at a very good height to be at its most effective. A full size vertical 1/4 wave would be about 37.5 meters tall. Impossible! Bending a 1/4 wave wire into an inverted L would still result in a very long wire - say 10 metres vertically and 27.5 metres horizontally. Still too large.

Full size top band antennas are big, far too big for my small plot, so I have tried a few different shortened 160m aerials. I really would prefer to use a balanced dipole not only for the radiation efficiency, but just as importantly for the lower noise on receive - like a ground mounted vertical aerial an inverted L can be rather noisy on RX. However I have to settle for a compromise, so shown in the drawings and photographs below is my current top band aerial, along with some previous experiments and ideas further down the page.
This incarnation of my Top Band aerial takes two forms. A compact Inverted L and, in its lower position, a less conspicuous sloping wire, shown below:


General layout of Top Band Aerial with fibreglass pole retracted to a height of 2 metres
Wire lengths are approximate: Inductor 5cm dia with approx 40 turns of 0.9mm e.c.w.

Building a 2m quarter-wave ground-plane antenna


The first antenna that you should consider building is the quarter-wave ground-plane antenna for the 2m band. They are very easy to build and will perform better than the antennas that come with most handhelds.

The quarter-wavelength, ground plane antenna is made up of one vertical element, called the driven element, and four radials. The radials make up the ground plane. An easy way to make this antenna is to use an SO-239 coax connector. The driven element is soldered directly to the center conductor, while the four radials are connected to the four holes in the connector’s flange. See the figure at right.

2m ground plane antenna

A simple 2m antenna can be made with an SO-239 connector and four short pieces of stiff wire.

Now, let’s calculate how long the elements should be. Since the wavelength of a radio wave is equal to 300/f (MHz), one quarter wavelength will be equal to 75/f (MHz). At 146 MHz, therefore, the length of the driven element is:

75/146 = .51 m

In practice, we have to make one more adjustment. Because a radio wave travels more slowly in a wire than it does in free space, the wavelength will actually be about 5% less in a wire than in free space. So, we multiply the wavelength in free space by .95 to get the length of the driven element:

.51m x .95 = .49m = 19.25 inches

The radials should be about 5% longer than the driven element. This isn’t really very critical, so if you make them 20.25 inches long, the antenna will work just fine.

You should make the elements out of a stiff wire. 12 AWG copper wire will work for experimentation purposes. Welding rod might be better for a more permanent antenna.

You need to solder the 19.25-in. driven element to the solder cup of the center conductor of the SO-239 connector. Attach the radials to the holes in the flange of the SO-239 connector with nuts and bolts. You can also use these nuts and bolts to mount the antenna to some kind of bracket. Bend the radials out to a 45-degree angle, connect a coax cable to it, and start having fun!

VHF antenna 144-146 mhz


The antenna in the figure is for the radio amateur band 144 - 146 MHz. Despite the fact that the antenna has five elements, it is not large, decent gain of 4 - 6 dB. This antenna for the 144 - 146 MHz is sufficient broadband and covers the entire two-meter amateur band. The antenna does not need a matching device, coaxial cable is connected directly to the vibrator. Antenna for the 144 - 146 can be made of wire with a diameter of 5 mm or pipes traverse can be wooden or made of the same material as the antenna elements. It is not advisable to use materials in combination aluminum / copper. The antenna does not need to set up, small inaccuracies sizes have virtually no effect on its performance. Who figured this antenna I do not know, but in this town it is used a lot of amateurs, dignity is a compact size. Easily fits in your car, can be used as a marching variant. Unfortunately more information about this antenna for the 144 - 146 MHz is not. Often use this antenna in a vertical polarization.




If one is interested mostly only on 40 meter working, he can think of a loop antenna. It is simple and at the same time very effective. For best results, it should be made as square as possible. It should not be made more rectangular as the efficiency will suffer. The overall length of the antenna in feet can be found out by the formula 1005/f MHz. For a resonant frequency of 7.05 MHz the total length of the wire will be 142 feet 6 inches. For antenna wire 16 or 14 SWG wire can be used. Use 75 Ohms co-axial cable for the transmission line. The antenna should be kept at a hight of about 6 feet from the ground level.

If vertical polarisation is desired, feed the loop in the center of the vertical sides. This will give low angle radiation. If one desires horizontal polarisation, feed either to the horizontal sides.

The directivity of the loop antenna is broadside from the loop. So the antenna may be hung in such a way for maximum direction. This loop antenna has 2 DB gain over the dipole. It works well on 20 and 15 meter also with compromising results. For an experimenter, it is an antenna worth giving a trial.

Hentenna - An ADR Antenna


N. S. Harisankar / VU3NSH
Tel : +91 491 2576102, 9895741932

Hentenna is designed in 1970s by Tadashi Okubo JH1FCZ, Someya JE1DEU. They are 6 meter hams in Japan. In Japan, the word HEN means 'interesting, unusual, strange' etc. Ofcourse, it is a strange antenna and it is an Asymmetrical Double Rectangle (ADR) Loop Antenna. This system has more gain than an ordinary square loop and has the less impedance (nearby 70 ohms). It has two loop sections L1 and L2. The L1 section is the radiator part and the L2 is forming for matching and it helps the low angle radiation (10 to 13 degrees). Refer QST-1982 Feb (by JJ1UMS) and ARRL Antenna compendium vol. 5.

It was described for the first time in QST magazine in February 1982 by Koji Sugihara JJ1UMS (Page No. 16 -17). This antenna will produce a 5.1 dBd gain and with a 1.3:1 SWR with an amazing band width of 6.5 MHz. It can be upto 10 MHz bandwidth with 2:1 SWR. I started this antenna project, for VHF operation, using 3/8th aluminium tube and with a fine feed point movable plate section. The plate I have taken was a plexi glass of 15" x 2" and of 6 mm thickness. A SO239 socket was fixed at the centre of this plate for the cable connectivity (Refer photographs). Both ends of the feeds are connected with the 12 mm x 12 mm and 20mm long aluminium solid blocks with screw fixing holes. A 1 mm brass road is used to connect the above block sections to the SO239 socket, as a feed line.

The Hentenna Asymmetric size combinations are ‘lambda by 2’, ‘lambda by 6’ rectangle and feed point is ‘lambda by 10’ approximately. This antenna is not an omni and it is a bidirectional type. The HEN Part (Strange or Interesting) is as follows; If this antenna is fixed horizontally then it will produce a vertical polarisation !!! If it is fixed vertically the polarisation will be in horizontal. This character is explained by F.C.Judd (G2BCX) in 2 m antenna handbook in the ‘stacked skeleton slot array’ (page number 89-92). i.e., “The vertical slot is horizontally polarised and vice versa”. The skeleton slot system was developed by B Sykes - G2HCG of J-Beams Ltd. The radiation pattern is just like peanut shell.

Hentenna - Horizontally mounted vertically polarized
Fig. 1. Hentenna - Horizontally mounted vertically polarized

Fig. 2. Feed point section of hentenna

When firing the antenna for the first time with the SWR meter, I fixed the movable section to ‘lambda by 10’ approximately, then I moved it up and down and took the readings (see the SWR graph given below). Then I changed the feed point to get a very low SWR with low and high power. I got a beautiful match at 25 cm from inner surface of the right side tube (element - loop 2) and this point gives a 6.5 MHz bandwidth with a low SWR of 1.2:1 !!! at a low height of 4 feet inside my QTH, I got VU2KOD repeater as 5 5 and 5 6 and all local stations around 10 kms. as 5 9 plus 20 dB. I done this project three months back with a search of unusual antennas. For testing and assembling this antenna my SWL Rejeesh also helped a lot. Make this bi-directional asymmetric double rectangle loop antenna and enjoy...

Fig. 3. Hentenna - SWR analysed chart

Fig. 4. Hentenna - SWR analysed chart

Fig. 5. Bidirectional radiation pattern of vertically polarised 145 MHz hentenna

Saturday, September 21, 2013

vhf antenna 5 * 5

To increase the gain of the antenna needs to increase its size. Maximum gain depends on its construction . But if there is no possibility to install antennas with larger sizes in the UHF band can apply another method , you can place already with the existing VHF antenna has one just like it. Thus obtained one antenna system consisting of two separate VHF antennas. In this antenna system to produce phasing power and antenna impedance transformation and selection of the distance between them. This principle of the antenna system can be used to further increase the gain. Merging the two antennas in a single antenna system stacked designated - " 5 * 5 " . Such arrangement of the two VHF antenna narrows the directivity pattern in the vertical plane and this allows an increase of gain. Gain antenna system also depends on the distance between the antennas themselves . Generally omnibus two identical VHF antennas to one antenna system leads to an increase in gain of about 3 dB. Below is the diagram of the antenna system of two antennas for VHF 144 MHz . One of the antenna gain of about 6 dB and the antenna system of the two antennas about 9 dB. This antenna system is 5 * 5 and has enough broadband directional. Figure A) shows an antenna system with conventional cutting vibrators (2) , the input impedance of each of the antennas of 37.5 ohms, is used to align coaxial cable ( two segments ) long 3L / 4 and impedance of 75 ohms. As a result, the input impedance of each antenna at the point of connection of the power line is 150 ohms (the transformation of resistance) , and with two antennas , it is reduced to 75 ohms. In Figure B) an example of folded dipole antenna for VHF system. In this case, the antenna impedance is 150 ohms as line segments used matching wiring line length L / 2 . These segments do not transform the input impedance , while merging the two antennas in the input impedance at 75 ohms.
Dimensions of antennas in the antenna system :
Reflector (1): 1028 mm . Vibrator (2): 995 mm . Director (3,4,5) : 927 , 914 , 914 mm .
Distances: Reflector - Vibrator(6-7) : 380 mm . Vibrator - Director(6-7): 508mm . The distance between the other directors ( 7-8-9 ) 508 mm .
The distance between the antennas of 1220 mm .

Saturday, September 14, 2013

vertical antenna for the 144-146 MHz range with 5.6 dB gain

As is known usual vertical dipole is omnidirectional in a vertical plane. A simple antenna with omni-directional (vertical dipole) , for all its simplicity of design has a significant drawback - low gain . In order to overcome this drawback has been developed vertical collinear antenna has more gain than conventional vertical antenna with gain 5.4 dB. Image vertical antenna gain is due to the restriction pattern in the vertical plane, the radiation pattern in the horizontal plane of the antenna remains the same round. Vertical antenna with omni-directional gain 5.4 dB and its dimensions in millimeters shown in the figure. The antenna is designed to operate in the 144-146 MHz amateur band . The vertical antenna can be performed on the wooden pole or the other insulating material. Since the connection point of the power line vertical antenna has a high input resistance of about ( 500 ohm ) , you need to connect a coaxial cable to a transformer or a quarter-wave impedance transformer is made ​​of an air line with its own impedance Z = 330 ... 390 ohms. The right figure shows how to perform phasing line segments , the turns around the mast antenna diameter of 160 mm .

vertical antenna

Sunday, September 8, 2013

Control System For A Small Industries With Low Budget & High Performance

For Examlpe :-

GUI Based Temperature & Level Indicator And Controller Using  Internet Connectivity To Control From Any Where 

Hello Friends Now here we design a one control system for a small industries,so that automation can also be possible in the small low budget  industries with Automatic Control loop with Control Panel &  Internet control panel so that they can observe & control sys  from any where in the world. 

Right Now basically cover only Two Close Loop  1 )  Temperature
                                                                               2)  Level

Here is the block diagram of the concept which we had design system.

In our control system is mainly divide in to 4 part
1.  The sensor and transmitter at the Plant Field
2. The Heart of the system 89V51RD2 Controller + ADC0808
3. Graphical  User-Interface At Control Room or Internet Panel.
4. Actuator And Display of the system   ( Feed pumps, Buzzer Alarms,LCD Display)  

Part 1   The sensor and transmitter at the Plant Field

We have used IR-Sensor for Level measurement of the fluid.Which consist of the pair of  one Transmitter and one receiver. So that by reflection of the IR-wave will give the information of the level of the fluid. See the basic concept of it in the figure  

The Output of the Receiver is changed according to the distance of the liquid form it. It is Directly proportional to Voltage generated at output.

For Temperature Measurement 

We had used LM35  temperature sensor, Which will give output accordance to the Current temperature and then it is calibrated in the Celsius or Fahrenheit as our requirement.  It is Directly proportional to Voltage generated at output 10mV/'C.   

The output of the sensror are ANALOG so they are  Given to the ADC0808 to convert it into the DIGITEL form as our controller is DIGITEL CONTROLLER 

2. The Heart of the system 89V51RD2 Controller + ADC0808

We Have used 89V51RD2 Micro-controller for the controlling of the our system because of some Features like it
  1. ISP  system so that we can load our program easily into this and its.   
  2.  5 V operating voltage from 0 MHz to 40 MHz
  3. 16/32/64 kB of on-chip flash user code memory with ISP and IAP
  4. Supports 12-clock (default) or 6-clock mode selection via software or ISP
  5. SPI and enhanced UART
  6. PCA with PWM and capture/compare functions
  7. Four 8-bit I/O ports with three high-current port 1 pins (16 mA each)
  8. Three 16-bit timers/counters
  9. Programmable watchdog timer
  10. Eight interrupt sources with four priority levels
  11. Second DPTR register
  12. Low EMI mode (ALE inhibit)
  13. TTL- and CMOS-compatible logic levels.


We had selected 0808 for the more Analog input can be added to it, as 0804 has 1 input analog input channel but 0808 has 8 analog input channels. Right now we had used 2 input only but for future expansion can also be considered here. that why we used ADC0808. 

Here is the basic Circuit of 89V51RD2 + ADC0808 Design in PROTEUS

3. Graphical  User-Interface At Control Room or Internet Panel.

We Basically Two Control panel are their : 1) SERVER CONTROL PANEL
                                                                 2) INTERNET CONTROL PANEL  


Here i have uploaded some control panel picture in below so you can understand the concept of it GUI + CONTROL of the sys.

Server Control Panel

Internet Panel Basically Design for the multi-control of the one System From any where in the world . 

This Internet Control Panel can be operated form any where from the world so the owner can see the Live status of their company . And also they have option to change the limits and set points. Maximum 254 Internet panels are see and control the panel.

4.Actuator And Display of the system   ( Feed pumps, Buzzer Alarms,LCD Display,Actuator )

Now if any system is their then controlling variable is controlled by the final control element which can be a Pump,switch,motor , valve any type of the actuator according to their system it is their . 

Now here i used the Pump as final controlling element . Two pump are their one is in flow and out flow. if the level is to low the in flow will automatically start and fill the water and if the level is to high then out flow will start and take out the water from the tank and maintain the level in the tank.

12 V DC Pump

This as Actuator for the system , it can also be Switch of control valve.

Now for Local Display  

Here i used JHD 16x2 LCD 



This will show the status of the parameter locally at the near the instrument so the worker can see the parameter that that place .

Critical situation Alarm 

For the Critical situation a alarm is place, which will give a voice alarm to the operator or worker the site of the instrument for inform them about the critical action so they can take required step about it clear that. 

Here i used the Small 4-20V DC volt Which give a beep on getting volts.

Description Of System To The Final To Industrial Site

We all know that the Automation of the industry always going to have good profit and More safety to our worker and also for large costly instrument ,  But For a small industrialist it is very costly to use PLC ,SCADA , DCS in small industry,So my Business Concept is to provide a Full-automation to small industry within their budget By design a their controlling Instrument using High frequency Controller and GUI software like Visual basic ,lab-view, Mat-labe,& GUI softwares. So That the small industry can also get a automation with according to their low budget + high reliable their industry  system with low man power & high profit output. In this system if they want we can also add the new feature  internet view or internet  control panel, so that the small industrialist can also see their company status form home or outside as we know  industrialist don't have manager in their company by have Android software + computer software for observation of status . so they have all type of function in low Budget More Profit. I would like to give a automation to low budget company with their requirement and output criteria. 

Here i had Maid one Live  system which is Analogous to the industrial process .  So we can easily get idea about the live real industrial system by this small model. The model is operating live so we can get real idea of function and working . We can also add PID Tunning in this System by adding much more function as per the required of the Client and function.

Blog writing is in progress please wait .........  Thank you