Yagi Questions & Gallery


Questions from Visitors

Many people have tried this DIY antenna project with great success in Australia, USA, Colombia, Uruguay and the Philippines, and I thank them for the feedback.



Q:...is it necessary to include a balun?
A:... NO it's NOT necessary for this antenna because you are generally Receiving and not Transmitting.
Want to know more... I did make a balun for this antenna by winding 6 rounds of coax around a 2" PVC pipe.
Held it with electrical tape and slid the PVC out. I bound this 'roll' with electrical tape to create my 'ugly balun'.
It's not a separate piece of coax! The "roll" is made from the longer transmission line coax and is placed close to the Driven Element.

Q:...My USB dongle has a cable with a large plug on the other end. I assume I need to also buy a large plug to connect the coax to this little lead?
A:... Yes. It sounds like you have a patch lead so use whatever fittings or adaptors YOU need to achieve a "join". Each time you introduce another adapter you degrade your signal a little more, so try to keep them to a minimum.

Q:...Can you clarify where you put the lugs onto the end of the Coax RG58. I presume that one lug goes onto the single middle wire and the other onto the multiple shield wires. Am I correct?
A:... Correct. Cut away about 25mm of the black coax outer plastic and pull some braided shield mesh to form it into single thick wire. Then carefully remove the white plastic dielectric to expose the centre wires and twist them into a single wire. It's a fiddly process but now you have 2 separate tails to work with and each tail is soldered to a lug.
The lengths you need will vary depending on where you drilled your Coax entry hole and the 'angle' you need to achieve.

Q:... You suggest cutting the beam through the hole for the driven element. Is there a reason that the cable ends need to be attached to the very inside ends of the driven element - could I attach the coax to either side of the driven element outside the riser?
A:... Where you attach the coax alters the electrical length of the Driven Element. (I know the physical length remains the same). To maintain the required electrical length of the Driven Element we need to have coax tails connected as close to the centre as possible.
In practical terms try for a 1mm gap between the two halves of the driven element then put the two holes/lugs as close to the ends as practicable but don't allow the two lugs to touch.

Q:... I could only get 12mm Aluminium tubing not the 10mm mentioned. Do I need to adjust the spacing to allow for the extra 2mm in width of each element?
A:... The technical answer is Yes... when you alter the diameter of the material it will change the specs but the alteration would be fraction of a millimetre. Most people wont be anywhere near that accurate in their building to begin with so I personally wouldn't worry about it. Just go with the measurements above.

Q:... You suggest 900mm length, yet the spacings of the elements from the reflector add up to 2,361mm. I must be missing something!
A:... Yep. You missed the keywords Element spacings: from Reflector. Those measurements are not ADDITIONS.

You take the centre of your Reflector and each one is measured from that point. So Driven Element is 74mmm out from the Reflector: Director #1 is 124mm out from the Reflector and so on... Until finally Director #6 is 670mm out from the Reflector
Your boom can be anywhere from about 700 mm onwards depending on how you're going to mount it. In my case a 900mm riser was a convenient length, with enough sticking out the back end to mount it.

Q:... Coax Question - Is RG213 better than the RG58? I read that it has a lower loss per metre. Even better than that is the LMR400 which has roughly half the loss of RG58?
A:... RG213 is better than the "cheap" RG58 coax and good to see you researching. RG213 is a thick coax and more difficult to work with as you have to finally connect to the tiny FME antenna fitting on the modem and the more adapters and patch leads you add will degrade your signal, so it's a trade off.
Working with a thinner coax gives more flexibility and there are high quality RG58's on the market but you have to search around for them. Jaycar generally sell the cheap coax with markings like /R or /CU on them.
My Coax is Cellfoam Low Loss RG58 Type RFI CAT. No 9001 which is rated as good as RG213 and if you're serious about finding this quality look for the "Installer" in your town who puts radios in Ambulances, Fire Trucks etc... They should have high quality stuff as it's a required spec for emergency vehicles. They may sell you 20 or 30metres, it's worth a try.

Q:... Can the Driven Element have wood inside? I realised that a standard wooden pencil fits perfectly inside the aluminium tube and makes the D.E. strong.
Another question; To change the polarity to vertical I only have to put the antenna with the directors in vertical position.

A:... A wooden pencil to keep the two halves apart and strengthen the whole thing is a brilliant idea as wood is also an insulator.
And, yes you are correct. If your nearest tower is Vertical you place your antenna so the aluminium cross pieces are pointing up and down. If your tower is Horizontal you place them crossways, just like looking at the horizon.

Q:... I'm asking about a Yagi antenna covering 850mhz to 2100mhz frequencies used in the Philippines. Some telecoms here use 850/2100MHz. I made your Yagi design, its 100% success to my broadband connection, could you pls give me the design so I would try?
A:... I don't build 2100MHz antennas so I can't recommend anything but.. If you check this Whirlpool.net.au page there is a list of Yagi's for various frequencies. Once you find the Yagi specifications you have my basic design/build ideas and should be able to make something just for the 2100mhz signal.

Q:... Do you have to tweak the Elite Modem so it knows you have an external antenna.
A:... There was no option to tell the modem I was using an external antenna until I upgraded the firmware for the modem. WOW an option then appeared asking if I was using an external antenna.. that was a surprise hahaha.

Q:... The 'telcoantennas' website says a Yagi provides upwards of 12db gain. What gain would you expect from this design? A:... Correct a Yagi = about 12dB gain (improvement) over a dipole antenna.
Don't worry too much about it, there are some basic rules like; the more Directors you have out the front of your antenna increases Gain but it narrows the bandwidth of the antenna... too technical for this project.
Want to know more... a simplistic explanation of how a Yagi works: Imagine a Vertical antenna, your signal is going out in all directions... a lot of your 'energy' is wasted if you didn't want it to go up, and out those other directions.
Professor Yagi & Shintaro Uda discovered they could harness all those outward radiating radio waves into one direction. The Yagi beam doesn't allow the signal to go out the back or to the sides but rather it goes in an elongated egg shaped 'lobe' in the direction that the beam is pointed.
And it works in reverse, the forward directors pick up a signal and effectively amplify it they pass it backwards from director to director until it strikes the driven element and it becomes of use to us.
The reflector at the back simply halts the process and bounces anything that hits it back to the driven element as well.

Q:... Would that NextG yagi antenna be suitable for mobile phone (next g 850 band) as well as NextG USB broadband? Both my phone and the elite usb modem have external sockets and I'm able to order the patch cables for both so everything should work fine hopefully A:... Yes, the frequency is the important thing and if your devices will accept an external antenna you can connect the Yagi to capture NextG/3G Frequency. USB dongle modems sometimes have external antenna ports but some do not.

Q:... looking at the photos of the Yagi it appears that the directional bars are the ones to be either horizontal or vertical. Is that correct?
A:... Yes, when we talk about the "plane" of the antenna being either horizontal or vertical we are talking about the cross pieces of aluminium - the elements.
Telstra/Bigpond mount their antennas either Vertical or SLANT on their towers..... you check your nearest tower (from the ACMA records) and position your antenna to match the tower they are pointing at.

Remark: This is an email from "M" regarding his search for NextG Antennas... made me smile
Below is a reply that I sent to a Retail outlet this morning after inquiring how much for their 16.5Db Yagi & good cable, delivered to Mullaley NSW. Answer $194.70
Thank you for the speedy reply. While I was looking on the net for antennas I came across vk4ion.au/nextg_yagi.html which details a home made yagi antenna with instructions. I had nothing to loose so in under an hour I was replacing my store bought 12Db with this PVC & aluminium tubing nightmare. Previously I was getting low signal strength @ 0.36 to 0.640KbS linespeed, and now 2.34MbS. Well I couldn't be happier. Total Cost about $6. But once again thanks for the reply. Your faithfully M.

In all fairness I must admit that my effort looks like a shower of s#*t but it works a treat for the 76Km straight line. I didn't have 10mm tubing for the elements, I used 12mm and the riser was 3x offcuts of 50mm PVC. The cable was supposed the be the best (Industry Standard) I was told, thin RG58. All I did was take the U-Beaut shop Yagi antenna down and put up the hours labour. I think I will go back to the drawing board and this time do a professional job on it, including replacing the RG58.

Reply:... Hello M. Thanks for the contact which made me smile.
Yes, we are trained to believe that retailers know best and we do need them to help those who can't clamber on the roof. But having said that, I want the Commercial guys to learn their craft and don't just take people's money. Your funny anecdote may inspire others and btw GREAT speedtest results too, thanks again for sharing.

Msg from James: I've now built a few of them! My biggest advice to those building it would be to get good coax, I ended up using RG213 as I was having trouble sourcing good quality low loss RG58 coax, this was a great improvement over the cheap RG58 that I originally got from jaycar although it is tricky to work with such large cable. James, Stanthorpe Qld

Reply:... Hi James, Thanks for feedback. Yes... there is no substitute for quality coax and it's annoying when a salesman says... "they're all the same mate" haha
When people take this leap of faith to build my antenna it's understandable they'll user cheaper coax to keep the cost down in case it doesn't work.
But if it does work replacing the coax will give that boost as you've outlined.

Update 2020

Telstra Australia has published the following...

" Telstra will be switching off 3G in 2024. Before switch off, you can use handsets supporting 3G on 850MHz... After switch off you will still be able to access the Telstra Network on 700MHz." Find out more at: Telstra 3G is Closing

  • 3G telecommunications is being retired in Australia in 2024 but I will leave this page live on the internet
  • The 3G mode [and 850MHz frequency] is still used in other parts of the world
  • With contacts from remote USA, Colombia & Philippines, people are building this antenna to suit local conditionss. So it is still a relevant resource.
  • I even had enquiries from Africa on how to use it to track lions (with their safety collar transmitters).
  • It is still a relevant resource

Personal Projects

Never stop learning, sharing knowledge or travelling

Each of these images will link to a dedicated webage where I share my Amateur Radio projects or travel pages.

ENVIS Dipole


Emergency HF antenna for 40 & 80mtrs



Building portable emergency cases



Find specifications & technical data

Digital TV Antenna


Facts about improving Digital TV

To New Zealand


Driving both islands in search of beer

Time Travel in Wales


Enjoying Wales & remembering the past

Scotland & city of York


Coast and Highlands travelling in 2022

Then to the USA


In search of good craft beers

Learning to make Cheese


Yumbo, delicious homemade cheese

Next up......................


To be sure..

Contact Me

Please email me if I can assist with information about my projects (or if you notice a broken link).