antenna

My Daughter Hijacked Our ARRL 2024 Field Day!

Each year on the 4th weekend of June, thousands of Amateur Radio operators operate during a 24 hour period primarily to simulate some sort of emergency scenario. Field Day can take many different forms. From a club setting up in a field with generators, to home stations running on grid power. For us, Field Day is somewhere in between these two scenarios.

. Since my daughter, KC8GRS, has moved back into the area, we have been running Field Day from my house using emergency power for the past few years. We both look forward to it and have a great time. To some Field Day purists, operating from a home station is frowned upon. Since Field Day, and the primary purpose of amateur radio is to provide emergency communications in times when traditional methods aren’t working. I ask the question, what is the most likely scenario in a grid-down situation? Going out in the middle of a cow pasture and setting up your gear (yes I have done that on Field Day) or staying home.

To me, the more likely scenario is to stay home. A great example of this is two years ago there were two tornadoes that ripped through our area. Large portions of our area were without power. I was without power for 4 days yet I stayed home, cooked my meals, helped my neighbors, and yes, was able to provide communications via my off-grid amateur radio station.

When we do Field Day, we operate class 1E battery. By running 5 watts we get a multiplier of 5. Since Laura likes to run digital, and I like to run CW, both of these modes get 2 points per QSO. With the 5 multiplier, we get 10 points per QSO – I like it! To make up for the low power, my main antenna is a 430 foot horizontal loop up 50 feet. This antenna seems to make up the difference when we are running QRP on Field Day.

Pages: 1 2 3

My DIY Drive-On Antenna Mast For POTA Activations

I have been doing POTA activations for a few years now, and I have been using an antenna mast that attaches on to my Reese hitch. It which works well. It doesn’t go straight out like most mast mounts do for Reese hitches but rather off to the side of my Jeep. One of my goals for a POTA activation is to have everything in my Jeep without loading anything. However, I have been known to forget my antenna mast mount for the Reese hitch.

Also as one of my POTA goals, I want to have everything I need for an activation in my Jeep ready to go. This way I don’t have to load anything, or forget anything. Since it is already in the Jeep.

My Mast Mount Off Of A Reese Hitch

I have had several people on ask about my mast mount using a Reese Hitch. So I have added a photo below. However this is for reference. This post isn’t about this mast mount. This is about a drive-on antenna mast mount that I can always carry with me in the Jeep.

DIY drive on antenna mast for POTA with a Reese hitch — My Old antenna mast mount using a Reese Hitch

This antenna mast mount uses two Reese hitch extensions that are welded on to a piece of 2″ square tube. It comes apart in two pieces. The vertical pipe on the left is welded on to a 2″ piece of square tube that fits into the Reese hitch extension. It works very well. The best part is that I can drive to a park and open the hatchback as if the antenna mount wasn’t there.

But like I said earlier, I have been known to forget to attach this antenna mount. Thankfully I also carry an End Fed Half Wave antenna as a spare antenna. The EFHW antenna seems to be a little better performer than the vertical wires I use. But it takes a lot longer to set up my EFHW than it does the Spiderbeam mast.

My vertical wire antennaa works quite well. And I will continue to use them as my main POTA antennas. For me the time it takes to set up an EFHW vs the Spiderbeam mast, the trade-off between a longer more difficult setup vs speed and ease isn’t worth it. I know a lot of you will disagree and that is fine. that’s just how I have chosen to run my activations.

Pages: 1 2 3 4

Can You POTA on 160 Meters? Lets Find Out!

Several months ago, someone on the Parks On The Air POTA Facebook page posed the question “Has anyone made a POTA activation on 160 Meters?” To be honest, I really haven’t given 160 Meters much thought, let alone for a POTA activation. So this got the wheels of thought churning in my head.

160 Meters is a unique band that covers the frequencies of 1800 – 2000 kHz. Its often referred to as the Top Band, not sure why, but it is. The biggest problem for me is the size of the antennas required. A classic Dipole antenna for 160 meters is approximately 246 feet. A full sized vertical is approximately 123 Feet. For most hams this is hardly practical – let alone for a POTA Activation.

Since my main POTA setup is with a 40 ft. Spiderbeam mast and a 35 foot wire hung from the top, I figured that would be my starting point. So obviously I would have to come up with some sort of shortened vertical antenna for 160 Meters. This made sense to me as I have had success building other shortened vertical antennas for my POTA activations.

My POTA station has an LDG Autotuner and all it needs is to have some sort of ground to work against, and a wire at least 1/4 wavelength long. What I do for POTA on 80 meters is have a coil that adds enough inductance to my 35 foot wire so that the autotuner “thinks” its tuning into a long enough wire. This works well for me, so I thought I would do the same for 160 Meters.

Pages: 1 2 3 4

How To DIY A Shortened 20 thru 40 Meter Vertical For POTA

There is something exciting doing a POTA activation where you hike in with all your gear in a pack and activating a park running QRP power. Since my original post about my first QCX-mini QRP transceiver, I now have additional QCX-mini’s that allow me to work my POTA QRP activations on 40, 30, and 20 meters. This meant I needed to build a portable shortened vertical for these bands. This particular vertical antenna build is based on my original Shortened 40 Meter Vertical but with the addition of being able to short the loading coil at the proper tap point for resonance on the 30 and 20 meter bands.

One problem I had with the original 40 meter vertical antenna, was that I used two 1/4 wave radials, which conventional wisdom says you should use with vertical antennas. On 40 meters, they are approximately 33 feet long. Which makes it more difficult to deploy the radials when in a heavily wooded POTA activation.

1/8 Wave Radials?

In doing some internet searches I discovered that it is possible to use radials that are 1/8 wavelength long — Yeah it sounds crazy to me too, but if its true, then it would greatly help the radial deployment issue on 40 meters. Granted at reduced efficiency, but I figured it was worth a shot. More on this later.

Since I already had a 20 foot collapsible fishing pole for my 40 meter shortened vertical, that is what I used for this multiband antenna. Since this was going to be for 3 bands, I wanted the loading coil low enough so that I could easily make a band change without lowering the vertical. Again, I went over to the coil shortened vertical antenna calculator page which gave me my starting points for the loading coil. Tuning this antenna for all 3 bands seemed trickier than normal. My guess is that I am using only two 1/8 wave radials.

The diagram below are my final dimensions. Your mileage may vary, but this is what I ended up with.

shortened 20 thru 40 meter vertical for pota sota activations WB8ERJ

For the loading coil form I decided to use an In Sink Tailpiece. My reasoning is this, typically people use standard PVC pipe for the coil form, which is fine, but the wall thickness of the pipe seems unnecessarily thick for my application. My main concern here was to put less stress on the wire that is the vertical part of the antenna. A toilet overflow tube is much thinner and lighter and works just fine. The outside diameter of my overflow tube is 1.5 inches. I am assuming that is a typical outside diameter. I cut the Sink Tailpiece 3 1/2 inches long, but 2 1/2″ would have worked just fine.

I used the coil shortened vertical antenna calculator based on where the coil is to be located in the above diagram and came up with a total number of turns of 33 with a tap at 13 turns from the top of the coil. If you have a different gage wire, put that in the coil shortened vertical antenna calculator instead.

Initially I built the loading coil with the calculated number of turns. As it turned out, I needed more inductance. In the photo on the next page you can see at the top of the last turn I added more wire. Lesson learned, wind more wire on to the coil than calculated.

Pages: 1 2 3 4 5 6

Build A Shortened 40 Meter Vertical For POTA / SOTA Activations

Recently I went on vacation to Virginia and wanted to do some POTA activations using my new QCX-mini transceiver. On this trip I wanted to hike up to the summits of various mountains that are in various national parks. Since my QCX-mini is the 40 meter version, I obviously needed an antenna for it. My personal preference for portable antennas is to use vertical antennas as opposed to a dipole or other horizontally based antenna. Since my QCX-mini is 40 meters, a full sized vertical, being approximately 33 feet high, is a bit impractical.

UPDATE: I have built a new version of this antenna that covers 40 through 20 meters. If you are interested in building a 3 band version of this shortened vertical, click here.

I have seen others using collapsible fishing poles for antenna masts, so I figured I would give it a try. I found on Amazon.com a 20 ft. Crappie Fishing pole that collapses down to just 4 feet. I also found a web site that calculates what is needed for a coil shortened vertical antenna – perfect!

From what I have read, a base loaded vertical is less efficient than one that has the loading coil that is more near the top. The downside of placing the loading coil higher is that it needs to be larger, which will add to the weight, as well as additional stress on the pole in windy conditions. What I decided on was placing the loading coil slightly higher than the center of the vertical antenna.

Given my design constraints and using the coil shortened vertical antenna calculator, I settled on my shortened vertical antenna design. The diagram below is what I came up with:

build shortened 40 meter vertical antenna for pota sota acvitations

I used the coil shortened vertical antenna calculator based on where the coil is to be located in the above diagram and came up with 23 1/2 turns of # 24 enamel wire. I used 24 gage wire because I had it on hand. If you have a different gage wire, put that in the coil shortened vertical antenna calculator instead.

Pages: 1 2 3 4 5 6

How to DIY an NVIS Antenna AKA Cloud Burner Antenna Using a Mag Mount

Part of being a ham radio operator is to provide communications in times of emergencies. With the upcoming Ohio NVIS Antenna Day, I decided to look into NVIS antennas. NVIS antennas, also known as Near Incident Vertical Skywave antennas have a high angle of radiation. Something on the order of 60 degrees, to straight up to 90 degrees. Unlike UHF and VHF signals, which typically have a 50 mile range with a yagi antenna up high, a NVIS antenna is designed for communication in the 75 – 500 mile range. Sometimes an NVIS antenna is referred to as a “cloud burner” since is directs most of its radiation more upward than a typical antenna.

The idea with a NVIS antenna is to radiate as much power as possible at a high angle and have it be reflected off the ionosphere. From a practical standpoint, NVIS communications occurs at 10 mHz and below. Another part of the NVIS antenna is the fact that it is quite low to the ground. This helps radiate the signal at a high angle, as well as make it easy to deploy. There ar many opinions as to the best height of an NVIS antenna, but everyone seems to agree on aprox. 1/8 wavelength above ground and sometimes less.

I wanted a NVIS antenna that was portable, easy to set up, and cheap (of course). As it turns out, I had practically everything on hand. For my NVIS antenna, I started out with my 2 meter mag mount for my car. Then it was just a matter of attaching a quarter wave wire to the mag mount, then just string the wire horizontally from the mag mount to a tree, or a pole of some sort.

Pages: 1 2 3