3 Elements Yagi optimized for 2m 146Mhz. The design is very similar to 3 Elements Yagi for 145Mhz for the boom and elements spacing. The only difference is on the cutting of the elements. Check the design for 145Mhz Yagi here.
Like most of my design this is an end mount type yagi which is more efficient than a mid mount type yagi as the mounting will not introduce a pattern distortion.
Similar materials are used in the construction:
3 Elements Yagi Antenna Materials List
1″ X 0.5″ Rectangular Aluminum tubing for the boom
3/8″ Aluminum tubing for antenna elements
1cm Outside diameter antenna tubing for elements holder
1pc SO239 connector
Pop rivets / Rivet tool
#12 AWG Copper wire with insulation (12″for Gamma match)
6pcs Stainless steel nuts and bolts 20mm length 3mm diameter
1, Butterfly nut and 1 bolt 18mm length 3mm diameter
Aluminum plate 0.5mm thickness
Collapsible tube (shrinkable tubes)
To check the antenna pattern and expected gain if the antenna will perform similarly on other bands these are the results with both slight increased in SWR and little decreased in gain on 144Mhz and 148Mhz respectively but the expected pattern are generally the same. I’m using 4NEC2 for antenna simulation and analysis.
Predicted Antenna Pattern for 146Mhz
Predicted Antenna Pattern for 144Mhz
Predicted Antenna Pattern for 148Mhz
For SWR curve this antenna exhibits a pretty wide band performance on 4NEC2 simulation.
Sleeve Dipole Antenna
Build a 2m VHF lightweight sleeve dipole antenna. A compact portable antenna and easy for deployment. You can even operate the dipole while holding it. Building it is easy just follow the antenna plans below. The antenna specifications are below including the testing video.
Antenna Gain: 3dBi
Features: Lightweight and Portable easy deployment
Building a 15 Element Yagi for 2.4Ghz Wifi frequency. This antenna build is very useful for extending your wifi range indoor or outdoor. The approximate gain of this 15 element yagi is approximately 13dBi with a good front to back ratio of 20.6dB. Beamwith is 40° horizontal and 70° vertical.
1. 12mm x 8mm uPvc moulding (Boom)
2. #12AWg solid wire for elements
3. Measuring tool / precision cutter
4. 1 SMA female connector
5. Coaxial cable suitable for SMA connector
6. Sandpaper or file tool for removing rough edges of the elements
Gain and and antenna patterns are from 4NEC2 antenna modelling software.
Some direct measurements from neighbors WiFi access point:
This first screen shot reading is from a WiFi card with a 5dBi dipole antenna
The second screen shot is taken from 15 Element Yagi antenna build taken indoors
As we can see from the above screen shots the initial measurement from a dipole yields -88dBm our reading from the yagi -76dBm direct calculation from the 2 values ( -88dBm – -76dBm = -12dBm) our yagi gain is almost equal to the theoretical gain of 13dBi. The above measurements are taken indoors the WiFi card is connected to a laptop.
So you follow the tutorial article on how to make the 3 Element Yagi on this page. You’ve even watched the tutorial video on how I build the 3 element yagi and wanted to duplicate it. You’re all set with all the materials at hand and most importantly you’ve got the perfect time to do it now. So you proceeded with the project, you cut the elements, marked the spacing, mounted the elements holder and things are looking good. Except for the last part the diagram seems too complicated to follow. So worry not this is the tutorial video on how I build the gamma match for my antenna build.
So to recap:
The gamma accomplishes 3 things:
1. Usually it’s a small diameter wire parallel and in close vicinity with the main radiating element, it will carry only a fraction of the main element current while being exposed to the same electrical field strength. This turns it in an effective up-transformer of the antenna input impedance. A sort of folded dipole performing an impedance step up.
2. It forms together with the main radiating element a closed wire stub, adding inductance to the antenna input impedance. If it is not required for matching, this additional inductance can be cancelled out with a lumped capacitor in series. A parallel shorted transmission line stub, adding shunt inductance.
3. The sheath of the coaxial feed-line (braid) is connected to the center of the main radiating element. When properly connected, a gamma-match also serves as a balanced to unbalanced converter or balun.
Here’s the how to video:
If you want a more in depth discussion and mathematics behind the gamma match read and download the gamma match document below.
A folded dipole is an antenna with the ends folded back forming a loop. The impedance of this antenna is around 300 Ω, so you may want to use a transformer or a λ/4 long piece of 120 Ω coaxial or 75 Ω cable to match this impedance to 50 Ω. Geometry is not that critical.
The Yagi-Uda antenna, commonly known as the Yagi, was invented in 1926 by by Dr. H. Yagi and Shintaro Uda. Its configuration normally consists of a number of directors and reflectors that enhance radiation in one direction when properly arranged on supporting structure.
The results of the measurements carried out in this study are presented in graphical form. They are intended to provide a simple means of designing a Yagi antenna of practical dimensions with maximum gain for the configuration under consideration. The purpose of these tests was to determine the following:
a. Effect of reflector spacing on the gain of a dipole antenna
b. Effect of different equal length directors, their spacing and number on realizable gain.
c. Effect of different diameters and lengths of directors on realizable gain.
d. Effect of the size of a supporting boom on the optimum length of parasitic elements.
e. Effect of spacing and stacking of antennas on gain.
f. Measured radiation patterns of different Yagi configurations
Building a high performance 3 Elements lightweight end mount Yagi antenna for 70cm UHF band centered at 435 Mhz. This Yagi build exhibits a gain of 7.66dBi at the center frequency 435Mhz for use in the Philippine UHF amateur band. Front to back ratio is 18.5dB, Vertical Beamwidth 106°, Horizontal Beamwidth 64°. Just like my previous design it uses direct coupling of feed point to boom and a gamma match to tune the antenna. This antenna will cover 430-445 Mhz UHF Amateur Band.
1. 1″ X 0.5″ Rectangular Aluminum tubing for the boom
2. 3/8″ Aluminum tubing for antenna elements
3. 1cm Outside diameter antenna tubing for elements holder
4. 1pc SO239 connector
5. Pop rivets / Rivet tool
6. #12 AWG Copper wire with insulation (12″for Gamma match)
7. Soldering iron
8. 6pcs Stainless steel nuts and bolts 20mm length 3mm diameter
9. 1, Butterfly nut and 1 bolt 18mm length 3mm diameter
10. Aluminum plate 0.5mm thickness
11. Collapsible tube (shrinkable tubes)
1. Boom Length 32 cm (Use rectangular aluminum tubing)
2. Reflector Element (length) = 34.00cm
3. Driven Element (length) = 32.50cm
4. Director Element length) = 29.50cm
Boom end to 1st U Bolt (hole) = 1.5cm
1st U Bolt to 2nd U Bolt (mounting holes) = 4.5cm
2nd U Bolt hole to Reflector = 3.81cm
Reflector to Driven = 12.60cm
Driven to Director = 5.40cm
Director to End of boom = 2.50cm
To increase the performance you may also configure the antenna in stack configuration by making two antenna’s and connect it with a phasing harness for increased performance.
Antenna Gain Simulation and Signal Pattern Using 4Nec2 antenna modeling.
Front to back ratio is 18.5dB
Vertical Beamwidth 106°
Horizontal Beamwidth 64°
Building the gamma match for 3 Elements Yagi UHF 70cm 435Mhz
Just like the gamma match for our 5 Elements Yagi the construction technique for building the gamma match for the 3 Elements UHF Yagi are similar (tolerance level of 3% to 5% on measurements for building the gamma match is fine). The gamma tube for the 5 Elements UHF Yagi is exactly 4.5 cm. Please refer to the diagram for actual measurements. This yagi will give you a good coverage from 430Mhz to 445Mhz on single configuration @ 1:1 SWR on center frequency 435Mhz and about 2:1 SWR on band edges.
Build a high gain 2meter vertical dipole array with this antenna plan. Ideal for repeater or base station setup.
Easy to follow build instruction by KG4JJH, with complete dimensions and diagram illustrations. Complete with antenna gain and pattern simulations and expected SWR response on the designed frequency.