Simple 2 metre dipole* for a 7m squid pole
This antenna comes to you from the home-brew shack of VK1NAM. No it doesn’t have a brand name, doesn’t claim to be a miracle device and doesn’t come with a 1 year warranty or a 2 year extended warranty. You will be pleased to know it works by radiating RF energy with 2 broadside lobes. How does it do that? Well it sits on the 5th section of a squid pole about 5 meters above the ground.
Yes it’s a simple 2m half wave antenna made from wire and a couple of adapters. Some of you may have similar adapters in your junk box. What does it cost? You will be surprised to know it’s not $$$$ hundreds and not even $20.00 The adapters are a few dollars each from an Ebay supplier and the wire was salvaged from a motor winding. The cable tie is from a bag of 50 purchased from a nearby hardware store at $4.00 per bag. For the home-brew champion you can build this antenna yourself and without the guidance of assembly instructions written in half Chinglish. Fear not, if you don’t have the exact adapters you can improvise, think of another way to support two pieces of wire only 497 mm long. My inspiration for home-brewing this antenna is from the joint-activations with Al VK1RX and the Mt Kosciuszko expedition. *I will take this opportunity to acknowledge Al’s 2m dipole design as the basis for my home-brew attempt, the difference is the center support. I will take a guess and assume his wire elements are similar in length. 😉
Why a simple dipole for Bimberi Peak you ask?
Bimberi Peak VK1/AC-001 is 1913 metres ASL a stone throw shorter the Mt Kosciuszko. When Andrew VK1DA and I activated SM-001 we estimated we would require a 5el 2 metre yagi, separate squid pole to support the antenna and 40 to 50 watts into the driven element. Haha wrong! But yes we did slug all that gear to the summit of SM-001 and spend 30 minutes in difficult conditions assembling the boom and elements then fighting the wind while trying to guy the squid pole. So what happened?
I worked Peter VK3PF, Ron VK3AFW and Allen VK3HRA (and Marshall) on their respective summits using the FT-857 and 45 watts into the 5el yagi. The furthest away being Ron on Mt Buller 180 km south-west. Yes signal reports were awesome 5-9 each way, even from Ron. What happened next? Not only was the squid pole supporting the 5el yagi (only just in 50 km/h winds) we had placed the 2m Slim Jim on the same pole. Next Andrew fires up the FT-817 (5 watts) and makes a call to Ron, Ron replied with a solid 5-5 contact, good grief, working Ron with the Slim Jim and yes 5 watts. That Slim Jim rocks! What was remarkable is the polarisation of each antenna was at 90 degrees to each other, Ron using a horizontal yagi and Andrew using the omni vertical. Andrew went on to work other VHF DX on the Slim Jim.
So at altitude you may work stations over the horizon say 150 to 200 km on 144 USB with only 5 watts into a simple antenna. Okay what’s that got to do with Bimberi Peak? I plan to be on Bimberi Peak 10 Jan 14 staying Friday night then early Saturday morning around 8 am I hope to work a few VHF DX stations, the kind of stations that run 400 watts into 16 – 20 elements muti-stack arrays. If anyone can sniff out 5 watts from a horizontal antenna at 1918 metres ASL, the VHF DX gurus can with their monster arrays and multi stage pre-amps. Working the local VK1 chasers should be a pinch.
The plan for Bimberi Peak is to undertake a ‘light’ activation using the FT817, a VHF and HF dipole supported by a 7m squid pole. Has this style of ‘light’ activation been proven? Well yes it has, Al VK1RX and I activated Mt Gingera in March last year. Al was using his version of a 2m dipole taped to the squid pole with 100 mile/hour tape and successfully worked Rhett VK3GHZ in Bairnsdale 273 km on 144.200 USB running 5 watts. Given the example at SM-001 and Al’s experience, my plan is to try it out on Bimberi Peak.
P.S. I forgot to mention you can store the copper wire elements inside the squid pole, rather than bending them to fit in your backpack.
Below are pictures of the antenna components, go for it, enjoy making your own 2m dipole for your next 2m activation. Simplicity is the key. 🙂
Update to this post. I have replaced the 1.6 mm elements, now using 3 mm enamelled copper wire. See the post dated 7 January 2014.