There is no shortage of end fed half wave antennas on the market. Over the years I’ve tried many variations and one of my personal favorites is the Spooltenna, both for it’s ease of deployment and very good performance. Their new Ultra model is my top pick and last week I put it on the air at one of my favorite local POTA locations.
That’s the subject of this week’s video: This End Fed Half Wave DELIVERS! Spooltenna Ultra POTA Setup https://youtu.be/7AyMLkW1Yh8
The battle of Smokey Hill: https://www.geocaching.com/geocache/GC82BKP_the-battle-of-smokey-hill
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Chameleon CFM-34 Carbon Fiber Mast: https://chameleonantenna.com/products/cha-cfm?bg_ref=ok7Ky4088r
RigExpert Stick 230 Antenna Analyzer: https://dxengineering.pxf.io/rEQxKD
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My antenna choices when band conditions have you up against the wall
Let’s face it. HF propagation hasn’t been very good lately. With a declining solar cycle full of geomagnetic activity, and summer propagation duldrums being of no help, it’s easy to become disheartened and discouraged.
I’m not saying the days of wine and roses are over, but it is certainly going to get a lot worse before propagation gets better.
There are a couple of things to be hopeful of, though. While the summer doldrums are a real thing; that is, our long days this time of year in the northern hemisphere disproportionately energizes the F2 layer, leaving little time for it to settle back down, that effect is temporary and will see marked improvement after the equinox.
But the general downward trend of Cycle 25 will continue, so here are some antenna styles that I will focus on to help get a good signal out during marginal conditions.
The Dipole
There is no dismissing the effectiveness of a dipole antenna. It is lean, mean, and gets the job done. The most fundamental of antenna designs does well to efficiently turn electromagnetic energy into radio frequency waves. But it does have limitations, such as requiring antenna supports or trees to properly deploy it, and for the most part you are limited to one band. Still, expect a good signal with a minimal investment.
Off Center Fed Dipole
A variation of the simple dipole is the Off Center Fed Antenna. By moving the feed point from the center of the antenna to an off center point so that 2/3 of the radiator is on one end and 1/3 on the other, you gain a multiband effect. A 4:1 transformer is required at the feed point for impedance matching, so there is a bit of a performance hit, But not enough to dismiss this antenna.
End Fed Half Wave
Again, a multi band antenna, but with a 49:1 transformer at the end of the wire element. On the fundamental frequency, that is the half wave length the wire is cut for, you will find very good performance. There is a hit on the harmonics and the transformer eats a bit of power. Still, wire in the air is a good thing and can provide surprisingly good performance.
Elevated 1/4 wave Vertical
This is a resonant vertical antenna tuned to a single band or frequency. Theoretically performance should be as good as a dipole, but ground effects do sap a bit of its power. I still have no reservations in putting one on the air, though.
Non resonant wire or vertical antenna
Some people believe that a non resonant antenna is highly inefficient, but in reality a 9:1 transformer is no worse than a well performing 49:1 transformer. It’s the mismatch in feed line impedance that sucks your power. A bit of care in selecting a wire length that is truly ‘random’ or non resonant to any target frequency and using a good quality coax to minimize losses will go a long way to improving these antenna’s performance.
I found all of these antenna styles very useful as were were slowly climbing out of the basement at the start of Cycle 25 years ago, and they will continue to be relevant as we decline in solar activity today.
Finishing Thoughts
This week hasn’t been a good one for getting outdoors. We’ve been under a heat dome with highs in the mid 90’s and today wildfire smoke from Canada and Northern Minnesota has come to make matters worse. There is a weather change forecast for the weekend, so I’m looking forward to cooler weather.
Speaking of this weekend, we’ll be out and out, camping in the Door County Peninsula. I hope to catch you on the air as I activate a few parks Friday-Sunday. Otherwise stay cool.
I hope to catch you on the air soon
Michael
KB9VBR
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