If you liked the 3 elements yagi, this antenna build is very close to the performance of that antenna. This VHF antenna is for 144Mhz with 10Mhz bandwith from 140Mhz to 150Mhz. The antenna measurements are computed and then simulated on 4Nec2 antenna modelling software.
Materials
1×1/2″ rectangular aluminum tubing for the boom 1/2″ aluminum tubing for the elements holder cut in half 3/8″ aluminum tubing for the antenna elements 1pc SO239 connector Pop rivets / Rivet tool #10 or #12 AWG copper wire with insulation for the gamma insert 3.5cm 3/8″ aluminum tube for the gamma tube 1 Butteryfly nut and 1bolt 18mm length 3mm diameter 4pcs Stainless steel nuts and bolts 20mm length 3mm diameter Aluminum plate 0.5mm thickness for the tuning stun Collapsible tubes different sizes. U bolt with mounting for the antenna mount
Construction
The antenna measurements is provided here for reference. Building it is straightforward you just need to follow the diagram and assemble your contraption. If in doubt you may watch the DIY video of me building a 3 elements yagi without power tools except for the drill.
I usually used a gamma match for my build, there is nothing special about this impedance matching system but since I’m using a grounded design, (grounded elements to boom) this is I think, the most logical impedance matching system to use, but that is just on me. The reason behind is that the boom is on the zero potential during transition period between the sinusoidal signal therefore elements can be grounded on the boom. In practice there isn’t a noticeable difference between the performance of a grounded elements and an isolated one (debatable). The caveats yagi’s driven element, should be isolated from the boom when using a different matching system. When using a gamma match the center conductor is just capacitively coupled to the driven element via the tuning stub, so it is not electrically grounded.
4Nec2 Data
2 Elements Yagi – free space antenna pattern, front to back ratio, beam width and approximate gain
2 Elements Yagi – antenna pattern considering ground effec, approximate antenna gain, front to back ratio and beam width
3D pattern and approximate gain considering ground effect and antenna currents
Approximate VSWR/S11 (Antenna reflection coefficient) from 4Nec2
Antenna frequency response/tuning
Antenna frequency response from antenna analyzer is very much similar to the modelling results from 4Nec2.
This 2 elements yagi antenna is intended for the 70cm UHF band center frequency is 410Mhz with 10Mhz bandwidth. The antenna measurements are computed and then simulated on 4Nec2 antenna modelling software.
Materials
1×1/2″ rectangular aluminum tubing for the boom
1/2″ aluminum tubing for the elements holder cut in half
3/8″ aluminum tubing for the antenna elements
1pc SO239 connector
Pop rivets / Rivet tool
#10 or #12 AWG copper wire with insulation for the gamma insert
3.5cm 3/8″ aluminum tube for the gamma tube
1 Butteryfly nut and 1bolt 18mm length 3mm diameter
4pcs Stainless steel nuts and bolts 20mm length 3mm diameter
Aluminum plate 0.5mm thickness for the tuning stun
Collapsible tubes different sizes.
U bolt with mounting for the antenna mount
Construction
Measure and cut the boom according to the diagram and assemble the antenna following the antenna construction technique here. Of course you may improvised and follow your own construction technique the goal of the video is to help you visualize the technique I’ve used to build this antenna successfully – but everything is not set in stone.
Note: You may have downloaded a wrong copy of the diagram that sets the spacing to 30.2cm – that is incorrect sorry my mistake I uploaded a wrong version of the diagram when I initially uploaded the article. It has now been corrected with the diagram below.
2 Elements Yagi – dimensions for 410Mhz with 10Mhz bandwidth. You may download the PDF Document here of the measurements. For the gamma match dimensions, you may use the measurements here this will work on this build.
Antenna Pattern from 4Nec2
Free space pattern analysis on 4Nec2
Antenna pattern and gain with respect to ground.
3D diagram gain, antenna current and antenna pattern with respect to ground
Antenna Tuning
Here’s the antenna frequency response and tuning video on my Youtube Channel
For yagi’s the longer the yagi’s the better the gain until you reached the point of diminishing returns – the point in which adding additional directors no longer produced a substantial gain or improving the front-to-back ratio. So worry not this 7 elements yagi is not there yet. The yagi design here is simulated using 4Nec2 antenna modeler, the measurements may not be your typical yagi, but I want it that way ;).
Thank you for the people that keeps the site afloat by asking me to design antenna for them, thereby buying the end product and testing the end result. Shout out to Mr. Jonathan Mendoza thanks to your generosity.
Here’s a quick look to the antenna that I built for him, he sent me the picture and I asked him if I can post it on my antenna facebook page he obliged, not knowing that I will also post it here. Bro, thanks a lot for the support!
Owner: Mr. Jonathan Mendoza – DY3BSW (Blackshadow), QTH: Marilao, Bulacan
To those people following my facebook page, this website and sending me a private message asking for the measurements, as promised – though it took a while, the diagram is finally out. Similar build instructions and materials are used same as my previous antenna builds.
Material list for building a 7 Elements 2m VHF Yagi
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. 14pcs Stainless steel nuts and bolts 20mm length 3mm diameter 9. 1pc, Butterfly nut and 1 bolt 18mm length 3mm diameter 10. Aluminum plate 0.5mm thickness 11. Collapsible tube (shrinkable tubes)
Cut the materials according the the measurements here:
This is the cutting chart for G7 antenna for those looking. I just uploaded it here for reference for those people that want to adjust their G7 antenna to other frequencies as stated in the manual.
This antenna built is similar to the 2×3 Compact Cross Yagi antenna with the addition of additional element on the UHF side. We have similar measurements for all the elements.
1″ X 1″ Rectangular Aluminum tubing for the boom (cut to length) 3/8″ Aluminum tubing for antenna elements (cut to length) 2pc SO239 connector #12 AWG Copper wire with insulation (12″for Gamma match) Soldering iron 6pcs Stainless steel nuts and bolts 30mm length 3mm diameter 6pcs Stainless steel nuts and bolts 30mm length 3mm diameter 1, Butterfly nut and 1 bolt 18mm length 3mm diameter Aluminum plate 0.5mm thickness Collapsible tube (shrinkable tubes)
4Nec2 data analysis
Antenna gain, beam width and predicted pattern spit out by 4Nec2 antenna modelling software
Antenna pattern for the VHF side
Antenna pattern for the VHF Side
Antenna pattern for the UHF side
Antenna pattern for the UHF side
Vector impedance analyzer frequency response data
This is the result of impedance analyzer testing for 2×3 elements cross yagi. Obtainable SWR is around 1.2:1 at the center frequency antenna reflection coefficient is at -24dB at VHF and -19dB at UHF. Pretty usable antenna, as you can see as well, the data spit out by 4Nec2 with regards to SWR on VHF side is close enough, I just directly cut the elements and assemble it with respect to the antenna measurement for the UHF side it was compensated with the use of gamma matching and correct length of the phasing harness.
Actual testing of the antenna
This is actual testing of the antenna see the video for SO-50 satellite
2 Elements Yagi Build for FM Broadcast Band 104-110Mhz
This antenna build is for FM broadcast band, the center frequency of this antenna is on 107Mhz as measured from 104 to 110Mhz with less than 1.5:1 SWR across those frequencies.
Materials
The materials required to successfully build the antenna are:
1″ x 1″ aluminum square tube 3/8″ anodized aluminum tubing #12 AWG solid wire for the gamma match (Watch building the Gamma Match video here) Suitable screws and nuts Different sizes of shrinkable tubes
The antenna placement and mounting are cut through the 1″x1″ aluminum square boom. The elements are inserted through the boom and secured by a mounting screw at the center. A gamma match bracket is made from a piece of aluminum scrap to form L and cut at the center to hold the gamma match in place. See antenna measurements.
Antenna Measurements
Antenna Pattern and Gain from 4Nec2
Expected pattern and SWR
Horizontal Pattern beamwidth / gain and front to back ratio
Vertical Pattern beamwidth / gain and front to back ratio
Build the gamma match for this yagi here. Although the gamma match is originally for 3 elements yagi antenna UHF this will also work with this 4 elements UHF yagi antenna.
Expected antenna pattern generated using 4NEC2
Antenna combined pattern
Horizontal pattern
4 Elements Yagi 70cm 409Mhz horizontal pattern
Vertical Pattern
4 Elements Yagi 70cm 409Mhz vertical pattern
Antenna Pattern on the low band 406Mhz
No skewing detected on the antenna pattern as generated by 4NEC2
4 Elements Yagi pattern @ 406Mhz
Antenna Pattern on the high band 412Mhz
Minimal skewing on the 412Mhz antenna pattern as generated by 4NEC2
4 Elements Yagi pattern @ 412Mhz minimal skewing on the pattern generated by 4NEC2
Complete Antenna Analysis using NanoVNA and N1201SA antenna analyzer
4 Elements Yagiat 157.000 Mhz measurements and spacing.
4 Elements Yagi for 157.000 Mhz
This antenna is 4 elements yagi built for the frequency 157.000 Mhz, in the Philippines most of the users of this frequency bands are Government Organizations, LGU’s, Civic Groups, Fire volunteers and the like. Although most of the requested antenna designs fall on the Amateur Band (144.000 Mhz to 146.000 Mhz) frequency. I decided to published the details of this antenna although not frequently requested. The details of the build is similar to building the 4 Elements Yagi for Amateur Frequency. Elements measurements and spacing are of course adjusted to resonate properly on the 157.000 Mhz band.
Antenna Specifications
Antenna Center frequency 157.000 Mhz Lowest usable band 152.000 Mhz Highest usable band 160.000 Mhz Antenna Gain: 9.52dBi F/B ratio: 9.87dB Beamwidth: 60° Vertical / 24° Horizontal
Expected Antenna Pattern Generated by 4NEC2
4 Elements Yagi expected antenna pattern at 157.000 Mhz. Generated by 4NEC2
Antenna Pattern Vertical
4 Elements Yagi expected antenna pattern vertical at 157.000 Mhz. Generated by 4NEC2
Horizontal Antenna Pattern
4 Elements Yagi expected antenna pattern horizontal at 157.000 Mhz. Generated by 4NEC2
Antenna Measurements
4 Elements Yagi at 157.000 Mhz measurements and spacing.
If you’re a fan of satellite monitoring (hunting for birds) as they call it, you probably want a bigger antenna with lots of elements for good contacts. Long antennas are good for satellite contacts with low elevation angle now the downside of those antennas are the lengths and they are cumbersome to work with specially if you’re home brewing and the materials available are not light enough. Each element will add up to the weight and will easily become unwieldy for hand operations holding the antenna on one hand and on the other the radio unless you are muscular then that would be easy. For casual contacts and mobility a compact antenna will get you where you want to go and still hunt for satellite with high elevation passes if you’re a fan of long distance and low elevation then this may not be for you.
1″ X 1″ Rectangular Aluminum tubing for the boom (cut to length) 3/8″ Aluminum tubing for antenna elements (cut to length) 2pc SO239 connector #12 AWG Copper wire with insulation (12″for Gamma match) Soldering iron 5pcs Stainless steel nuts and bolts 30mm length 3mm diameter 6pcs Stainless steel nuts and bolts 30mm length 3mm diameter 1, Butterfly nut and 1 bolt 18mm length 3mm diameter Aluminum plate 0.5mm thickness Collapsible tube (shrinkable tubes)
4Nec2 data analysis
Antenna gain, beamwith and predicted pattern spit out by 4Nec2 antenna modelling software
2×3 Cross Yagi VHF side – VHF side data was optimized using 4Nec2 antenna modelling optimization option SWR is spot on at 1.1:1
2×3 Elements cross yagi UHF side – don’t worry with the SWR data being spit out by 4Nec as you still need to match the UHF antenna for optimum SWR. The gamma matching can bring it down as you will see on the vector impedance analyzer.
Vector impedance analyzer frequency response data
This is the result of impedance analyzer testing for 2×3 elements cross yagi. Obtainable SWR is around 1.2:1 at the center frequency antenna reflection coefficient is at -23dB at VHF and -19dB at UHF. Pretty usable antenna, as you can see as well, the data spit out by 4Nec2 with regards to SWR on VHF side is close enough, I just directly cut the elements and assemble it with respect to the antenna measurement for the UHF side it was compensated with the use of gamma matching and correct length of the phasing harness. The capacitance of the gamma match when un-attached to the antenna assembly is around 10nf (0.01uf) and 20nf (0.02uf) respectively for UHF and the VHF side as measured using capacitance meter.
Actual testing of the antenna
This is actual testing of the antenna see the video around 2:30-2:38 I called out DV2JHA unfortunately we didn’t manage to confirm a successful QSO until the satellite signal started to fade out. Over all it’s a successful build.
This is the actual measurements of the cross yagi antenna I’ve used for satellite work, though the inline version of this yagi in which the VHF and UHF side are mounted inline but on the opposite side of the boom will also work for satellite communication. Inline version is here.
I have optimized this antenna for 145Mhz and 435Mhz painfully adjusting the exact length of the phasing harness to obtain lowest possible SWR/S11 curve on the antenna analyzer (measurements taken while actually holding the antenna). I just use 1/4λ length of the phasing harness, factoring the velocity factor of the coax for the actual length of the cable. VHF 145Mhz and UHF 435Mhz are complimentary harmonics frequency by design, actual length of the phasing harness are equal and using PL259 connector at both ends of the coaxial cable this connects to T-connector SO239. Patch cable is RG58 coax connector at the end is PL259 which will connect to the T-connector SO239, the opposite end of the RG58 coax is an SMA male connector which connect to my Vector Impedance Analyzer and also double as a patch cable for the radio which is about 65cm.
4Nec2 data shows beamwidth, expected pattern and predicted gain.
145Mhz 4NEC2 Data
435Mhz 4NEC2 Data
Antenna analyzer measurements and actual video footage
Measurements are taken while holding the antenna and the analyzer since we know that yagi interacts with the actual measurements if it’s too close to an object. This is to simulate the actual use case when using the antenna aiming it to the satellites.
Actual build, measure, cut and drill
These are some photos I took when building the antenna.
Preparing the materials 3×5 cross yagi and drilling holes.
Mounting the elements of the 3×5 cross yagi. Elements are fastened at the center with the screw, chosen so that it just touches the wall of the boom.
Preparing the feed point. Dual feed point which will connect to the T-connector via phasing harness
Gamma match preparation which will serve as our feed point for our yagi
Gamma Match final look and feel. The tuning stub are now properly connected to the antenna.
Initial testing of this antenna
I initially test this antenna using a phasing harness of 75ohms at 1/4λ x 3 for the actual length of the harness considering the velocity factor of the coax. The final use case testing, uses 1/4λ x velocity factor for the actual length of the phasing harness.
The fun part programming the radio before the hunt
Programming the radio with the satellite frequencies before the actual bird hunting. Since I work on a budget a Baofeng radio will suffice. I used a CIGNUS radio a rebranded radio that uses Baofeng internally ;). I encoded the frequency on the radio using CHIRP taking note of the CTCSS tone for each satellite and marking the channel name as name of the satellite and U for uplink D for downlink and A for arm to trigger some satellite timers before use.
Programming the satellite frequencies before actual hunt. This setup will work on cheap radios for the budget concious ;).
Cignus UV85 a rebranded Baofeng radio which I uses for satellite work. Who say’s you need too expensive gear to work satellites?
Aside from programming the frequencies on your radio you also need a satellite tracker to predict the passes of the satellite you’re hunting. I uses Gpredict which works on both Windows and Linux machines, for Android you may use AmsatDroid Free version and tons of other satellites tracking apps on both Android and IOS.
I use Gpredict for satellite tracking which work on both Windows and Linux machines, because of a very useful interface for predicting satellite passes. You may also use apps on both Android and IOS smart phones
The fun part really start when you begin the hunt and successfully received a very readable reception on your radio coupled with your homebrew antenna. If you’re not familiar with the actual satellite operations listen first until you feel comfortable pressing the PTT on your radio. Satellite resource hog are always frown upon so be courteous every time. Have fun!, and if you feel this will help someone feel free to share, thanks again!
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