3 Elements Yagi 70cm (Lightweight End Mount) Compact

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.



3 Element UHF Compact

Download yagi dimensions here

3 Elements Yagi 70cm UHF Antenna Materials List

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)



Measurements

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

Spacing:

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.

Combined Pattern

Combined UHF 435Mhz

Gain 7.66dBi
Front to back ratio is 18.5dB
Vertical Beamwidth 106°
Horizontal Beamwidth 64°

Vertical Pattern



Horizontal Pattern

Real Ground



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