Antenna Plans

Build the 3 x 5 Elements 2m/70cm Dualband Yagi

Build your own 2m/70cm 3 Elements VHF by 5 Elements UHF Yagi antenna with excellent gain for both VHF and UHF operation. This antenna is designed for amateur band frequency for both VHF (2m) and UHF (70cm). The antenna has good reflection coefficient and VSWR ratio @ 1.2:1 at center frequency and 1.7:1 at band edge.

Antenna Specs from 4Nec2

VHF Gain: 7.25dBi @ 145Mhz
Beamwidth: 114° degrees
Front to Back Ratio: 14.1dB
VSWR: 1.0:1

Expected pattern VHF

UHF Gain: 10dBi @ 440Mhz
Beamwidth: 60° degrees
Front to Back Ratio: 14.4dB
VSWR: 1.2:1

Expected pattern UHF

Building Video 3 Elements by 5 Elements 2m/70cm Dual band Yagi including Tuning

Material list for 3×5 Elements Dualband 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. 2pc SO239 connector
5. Pop rivets / Rivet tool
6. #12 AWG Copper wire with insulation (12″for Gamma match)
7. Soldering iron
8. 10pcs 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. 4 X 2″ Aluminum tube for bracket
12. Collapsible tube (shrinkable tubes)

Gamma Match for Dualband Yagi

24 replies on “Build the 3 x 5 Elements 2m/70cm Dualband Yagi”

sir, if sell it “Build the 3 x 5 Elements 2m/70cm Dualband Yagi” baka puwede mo akong pag bigyan, bahala padala mo lng, pre-fubricated ako nalang ako nalang mag rebits. puwede email mo ang presyo, new hoby po sir 73

hi. i like your antenna . I am new on ham world , i have a question : any form to calculate Phasing harness for your yagi antenna ,
thanks from MEXICO XE2MBJ .

Good day sir,pwede ba makahingi ng sample para sa computation ng phasing harness?d ko kasi maintindihan.maraming salamat.

To compute for the phasing harness, it’s 1/4 wavelength of the center frequency * VF (Coax Velocity Factor * odd number multiple, i.e (Antenna Center Frequency is 145Mhz get the 1/4 wavelength of 145Mhz, its equal to 19.4 inches or 49.276cm multiplied by coax velocity factor taken from coaxial cable datasheet of 75ohms RG59, (Phasing harness are usually constructed from 75ohms coax) example here >>> with 85% velocity factor multiplied by odd number multiple ( this is to cover distance separation if you are stacking antenna) so to continue 49.276cm * 0.85 * 1 = 41.88cm (length of phasing harness you can extend the length by multiplying it with any odd number 3,5,7 etc. to cover your desired length.

Thanks for the comment, but you are free to look for any resource you need outside of this website. I don’t receive any contribution to run this page from anyone, so that helps in maintaining the servers and continue sharing the content for free. Have a wonderful day cheers 73!

love your videos and your designs on your yagi antennas
please fwd info on some plans if you could love to design some of your antennas you have made for my own uses thanks so much…
my wife is from the Phippines from Clarin Misamis Occidental,
do you operate on the repeaters there in the Phippines allstarlink System

Hi Ted, the measurements antenna plans are available here on the website under the Resources menu >>> Amateur Radio >>> Antenna plans. Occasionally I’m using echo link but not too active. Thanks for looking around.

Hi all…Can you use two of these antennas with a
rhcp phasing harness with one feed line?If so what is the calculation for the harness?

Hi Noel, that is a dualband antenna – circular polarized antenna uses same band mounted in X or cross configuration ( better configure your antennas that way rather than using two of these). You need a phasing harness 1/4 wavelength * Velocity factor in odd order multiple to combine use 75ohms coax and use a phase delay stub 50ohms coax to achieve the phase angle delay. This video can help you in computing your phasing harness, excel calculator also included in the description >>> for the phase delay also a 1/4 wavelength * Velocity factor, piece of 50ohms coax connected at the end of the phasing harness connected to the antenna feed point of one antenna in X configuration.

Thank you very much sir Ephraim. Your video is very educational, i will try to Compute my phasing harness. Again, thank you and been very greatful for your support.

Do you really need a gamma components if you are using a diplexer/duplexer to split the signals? I’m trying to built a dualband as suggested with these plans but leave out the gamma components and adding a diplexer/duplexer.

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