4G LTE Yagi antenna for ATT

Build out of my Yagi-Uda antenna tuned for the ATT 4G LTE B17 band. 15db theoretical plus a mast for a real world gain of 21db!

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I was getting 1 bar of signal and the corresponding dropouts, poor performance, and general frustration that goes with it. Given I spend most of my day on VPN, the dropouts were getting really annoying. This antenna, and a temporary ~24ft mast made from a telescoping painting handle, solved that. We had a storm the same day I put it up and it barely moved in the wind.

This was attempt number 2. Turns out brazing aluminum distorts it way too much to be worth it, and I built the first one for the wrong frequency. The Verizon 4G LTE frequency I designed that one for is centered at ~10% higher which would have dropped my theoretical gain to something like 4db. The first attempt was a MIMO cross polarized version, but upon testing, gave no appreciable gain at ground level.

This one was riveted and went together much faster. This one gave me 11db at ground level, and 21db once I raised it up to get over some of the trees and hills between me and the tower... ~9 miles away.

This is the output you will get from the from the Yagi Calculator. 

These measurements are only valid for a 3/4 in (19 mm) boom and 1/4 in (6.35 mm) elements.


Yagi design frequency =725.00 MHz

Wavelength = 414 mm

Parasitic elements contacting a round section metal boom 19 mm across.

Folded dipole fully insulated from boom

Director/reflector diam = 6.35 mm

Radiator diam = 6.35 mm


212.4 mm long at boom position = 30 mm (IT = 96.5 mm)


Single dipole 190.8 mm tip to tip, spaced 83 mm from reflector at boom posn 113 mm (IT = 86.0 mm)

Folded dipole 194.6 mm tip to tip, spaced 83 mm from reflector at boom posn 113 mm (IT = 88.0 mm)




The abbreviation "IT" means "Insert To", it is the construction distance from the element tip to the edge of the boom for through boom mounting

Spacings measured centre to centre from previous element

Tolerance for element lengths is +/- 1 mm

Boom position is the mounting point for each element as measured from the rear of the boom and includes the 30 mm overhang. The total boom length is 1238 mm including two overhangs of 30 mm

The beam's estimated 3dB beamwidth is 37 deg

A half wave 4:1 balun uses 0.75 velocity factor RG-6 (foam PE) and is 155 mm long plus leads


Measurements are taken from the inside of bends

Folded dipole length measured tip to tip = 195mm

Total rod length =422mm

Centre of rod=211mm

Distance BC=CD=80mm

Distance HI=GF=77mm

Distance HA=GE=104mm

Distance HB=GD=131mm

Distance HC=GC=211mm

Gap at HG=6mm

Bend diameter BI=DF=34mm

If the folded dipole is considered as a flat plane (see ARRL Antenna Handbook) then its resonant frequency is less than the flat plane algorithm's range of 10:1

  • 48 × in x 3/4in Aluminum tubing Bought 12 feet for $20 to avoid the cut charge.
  • 10 × ft x 1/4in Aluminum Rod 12 feet was $6.
  • 1 × 3/8in x 2in x 1.5in scrap of polycarbonate (Lexan) Used to mount the driven element neatly
  • 25 × ft RG-6 cable 6 inches for a Balun, and remainder to connect it to my hotspot. Yes, I know it's 75 ohm impedance does not match the 50 ohms the hotspot wants, but I read at 700 mhz it doesn't matter much anyway and it was low loss.
  • 1 × RG-6 connector

View all 7 components

  • 1
    Step 1

    Print out the measurements table.

  • 2
    Step 2

    Cut your elements to length, adding 1 mm, starting with the longest ones.  As I don't own a band saw, I found my scroll saw worked well for this.

    Sand each until it hits the target length, squaring up the ends.  If you over-shoot, cut it down to be the next smaller element.  You need to be accurate to within 1 mm for good performance.

  • 3
    Step 3

    Cut your 3/4 in tube to length.  Square up the ends as you'll be making a lot of precise measurements from one end.

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