Antenna decisions

A multiband rig requires multiband antennas

One of the reasons that I liked the Yaesu is that it is an all-rounder, spanning the most common amateur bands. But how do you get that into the air?

I think more is written about antennas then about everything else ham combined. The reason, of course, is that every antenna is some compromise, and that in turn means that you have to think really hard about what you want.

First of all is space. I rent a house, so big projects involving concrete, mounting stuff on the roof, etcetera, is out. I wanted something that doesn’t go too high, because the higher you go, the more likely you need to do permanent “damage” to your landlord’s property ;-).

Second, for me, is simplicity. The less hassle with antenna tuners (the FC-30 on my transceiver only goes to a 3:1 SWR) the better, and I certainly did not want to invest in an antenna tuner at this time. One of the ideas of this hobby is to learn about electronics so everything I’m doing with premade stuff is just a learning experience - the real work is going to be done later using a soldering iron and making the max of my advanced license (when I obtain it).

For VHF/UHF, it is actually quite simple - a trapped monopole will work fine for the most used bandwidths but then I saw on Radioworld’s website a Discone by MFJ and I decided to risk it. Once I have that up, I have a “good enough” transmission antenna for all high frequency bands and a very fine wideband receiving antenna. After all, worst case all I need to get to is the nearest repeater.

For HF, I looked at a lot of antennas. Given that I didn’t want to build big installations, verticals and beams were out so I concentrated on wire antennas. I started looking at G5RV, which is trivial to build but has mediocre SWR - certainly not good enough for my simple tuner.

Next, I looked at all sort of dipoles - multiband, trapped, etcetera. This was also the point where I started doing simulations (using cocoaNEC) and I quickly discovered that a dipole that isn’t high enough radiates mostly upward. I think that, over Toronto, the clouds are already warm enough :-)

After some more digging I landed on an interesting design by G7FEK. I have a small backyard (well, probably large for Toronto), and it fit mine perfectly. Also, it is quite simple to build and has decent SWR on most bands. However, it wants to be decently high, and - being basically a monopole - needs a good groundplane. My girlfriend maintains the backyard, and I had my doubt about installing radials everywhere.

I was about to give up and buy an antenna tuner when I re-opened an article I read months ago and then put away. It discusses the Balanced Termination Folded Dipole and it pretty much just what I wanted. More below.

So - plans. I’ll buy a fiberglass telescoping pole and tripod, mount the Discone on top, hang the T2FD off it, and then I should be able to cover pretty much all bands.

The T2FD

Some people will probably tell me that I rejected a cloudwarmer and decided upon a resistor warmer instead. However, I want to make some points about why I think it’s a decent option:

The T2FD requires a high-ratio balun (higher seems to be better) and a resistance that can dump a lot of power. I decided that building these items would be too cumbersome so I bought them from BuxComm ready-made. With shipping to Canada, the two parts are around $100 which I think is an ok investment for an antenna.

Needless to say, I’m eager to start building this stuff and get on the air!

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© 2014 Cees de Groot. Licensed under the MIT License.