"Residential" Off-Centre-Fed Dipole
The quintessential issue with having a QTH antenna is space. Most residential lots tend to be restrictive about what kind of antenna a person can install. So you want the most bang for your buck, so to speak. Or perhaps better said, the most bands for your buck. Enter the Off-Centre-Fed Dipole for residential use. There are other configurations of this that can go all the way up to 80m if you have the space to do it. But this one gives you 40m-10m.
This post was inspired by the following video by Ted Edwards, W3TB. It is an excellent video for highlighting the advantages of an OCFD. In the video, he makes mention of an article that was published in the November 2018 edition of CQ Magazine. I wrote to Ted and he was kind enough to pass it along to me. Click here for the PDF version of that article.
The OCFD antenna needs a 4:1 balun/transformer to knock the ~200ohm impedance down for the rig. Ted recommended to me to use the grey 4:1 LDG instead of the green as 'a current balun is a better answer than a voltage balun' for the OCFD.
What makes this a "residential" antenna is the shorter overall length. And, it differs a bit from other OCFDs in that it isn't exactly the typical 1/3 2/3 split. This antenna uses 27' and 41' measurements. The article and video goes into full detail about the design considerations as well as the SWR readings - all of which are manageable with an onboard or external tuner. This convenience with low trade offs, as well as gain and the directional nature of this antenna make it an awesome choice for a home setup or for portable use.
In my testing at home, I paired the 4:1 with a 1:1 choke to clean up the common mode current. This resulted in very flat SWR readings across the bands. I also added a bit of strain relief in the form of a piece of dollar store cutting board to ease the wire tension.
I ran a WSPR test on this antenna on 30m and this map was the result. As you can gather, the antenna has awesome coverage of North America, Western Europe, and South America! The added perk is you can aim this antenna wherever you want to work more as Ted does for contesting. If you're looking for a slick antenna for your QTH or portable, look no further than the Off-Centre-Fed Dipole!
Thanks for checking out this build!
VE5REV 73!