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