When I began construction of a dedicated 8-Circle Receive Array antenna system for the low bands (160m – 40m) some time ago (see part one in this series for details), I knew that I’d have to use good Ham Radio grounding practices…
This is an article about Ham Radio grounding that I wrote some time ago when I added a second ground and entry point for my shack for some additional antennas. The ground system used was a simple one that would make a good system for a new HAM’s first station. The copper bracket on the rod can mount the feed line arrestors needed for feed lines before they enter your house. All one needs is the ground rod, the bracket, arrestors for your feed lines and a 12 gauge wire into your shack to ground your radio and you’re ready to get on the air. You can also use the arrester as a place to disconnect your feed line(s) when you’re not using the station to protect your QTH from lightning.
Living in a community that expressly prohibits ham radio towers often means enduring constant frustration trying to work DX with wire antennas or a multi-band vertical with what is always an inadequate radial field (read: less than 200 radials) over the “worse soil in the world”. My mantra of “work ’em on all bands and all modes” that I pursued for many years from my NH QTH has morphed to “hope I can hear them and they can hear me”. My lot can support a 40-foot tower that would be great for a small beam like the Cycle 24 used during the World Radiosport Team Championship a couple of years ago. Unfortunately, I would never get past a permit for the tower base if I ever tried to put one up.
Ah, but there is hope. The frustrations wrought by CC&R limitations often bring out the ingenuity in hams. Thanks to Layne, AE1N, I visited the website of Jeff, AC0C (see AC0C.com). Jeff lived in a condo with the no-tower restrictions. He looked over the attic where he lived and set about figuring out how to build an array of beams using the roof support structure. In a triangular volume measuring 16 feet at the apex, 20 feet long, and 40 feet wide, he managed to cram in a 22-element array that covers 160 – 6 meters! A scan of Jeff’s website is a testament to a ham’s perseverance to build an antenna farm where common sense says you cannot. Jeff used the popular EZNEC modeling program developed and maintained by Roy, W7EL. The overall configuration of the project shown on Jeff’s website looks like the proverbial rat’s nest. Somewhere on his site he mentions using over 1000 feet of coax, hundreds of ferrite cores, dozens of relays, and numerous switching boards to select the desired antenna while holding the RFI beast at bay.
Intrigued by Jeff’s work, I decided to take a look at my garage attic and see what I could do. My attic measures about 17.5 feet long, 19 feet wide, and 5 feet at the center above the floor. There is usable space beyond the garage over the remainder of the house that runs to the back, providing more depth. Unfortunately, my attic runs N-S so that any fixed antenna would have to be situated to favor a pattern to the E/NE direction for DX. I studied Jeff’s design for his 2-element 40 meter Yagi and decided to scale it for 30 meters. Each element resembles an inverted-V with the lower half of the ends bent at right angles to run horizontally along the floor of the attic. The horizontal portions of each element run toward each other so that the antenna resembles a modified “bent” Moxon antenna. (The Moxon antenna owes its design to Les Moxon, G3XN (SK). It is a 2-element beam that resembles a rectangle, is easy to build, and is forgiving in dimensions for a given band.)
I modeled the antenna with a separation of 19 feet between the elements and inserted loading coils in the driven element to shorten them. The apex height of the antenna is only about 14 feet above the ground so I was not expecting spectacular gain in the primary direction (North). The resulting pattern resembled a low dipole with maximum gain of 4.5 dB North and South, dropping to 3.4 dB at 45 degrees. While this may seem respectable, it occurs for an elevation angle of 45 degrees which means it would not work very well for typical DX angles. Indeed, when I looked at the gain performance at 24 degrees elevation, I had less than a dB. (The astute DX’er will notice that good DX performance occurs for elevation angles of 15 – 20 degrees. When limited to a height of 14 feet, the gain profile at 15 degrees is over 8 dB down from its peak.) Figure 1 shows the layout of the antenna. I realized that I’d be better off with a 30-meter inverted-V dipole off the back of the house.
Not to be deterred, I then modeled a 17-meter 2-element beam using relays to disconnect the 30-meter element at its coils and inserting an inverted-V element between the 30-meter elements to act as a director for 17. Figure 2 shows the results where the driven element is on the right and the director is at the center.
The performance for 17 meters was similar to 30 meters with a modified dipole pattern. The gain was a little better at a 24-degree elevation angle but still less than 2 dB. Again, better to stay with my inverted-V that boasts a 3.8 dB gain toward NE.
While I pondered my next move, it occurred to me that what worked for Jeff might not be the best idea for me. All that coax and those ferrite cores pointed to a lot of blood, sweat, and tears to get rid of RFI gremlins that such close quarters tend to foster. I considered using relays to change bands by lengthening or shortening the antenna elements. However, this would mean control cable wires from the shack to the antennas, themselves inadvertent antennas when transmitting. There has to be a better way.
Then, the long-dormant light bulb in my head came on. Why not try a 2-element wire beam? I looked at a model for such a beam for 17 and 15 meters, 2 elements for each band on the same “boom” and each fed separately. The results showed 17 meters behaves as expected with a gain of 6.2 dBi and a F/B of 21.6 dB. However, the 15-meter portion had a peanut-shaped pattern that was reversed from the intended direction with a F/B of less than 5 dB. I adjusted the height of the 15-meter elements within the available limits but to no avail.
Now what? I looked at the Moxon design again for its space-saving feature to see if I could get more isolation between the beams. I pulled up the file for the 2-element 17-meter beam and another file for a 15-meter Moxon beam. I merged the two antennas and juggled the positions so that the Moxon was a foot above the wire beam. Figure 3 shows the EZNEC model.
Figure 4 shows the azimuth gain pattern for the 17-meter beam.
Changing antennas for the 15-meter Moxon antenna produces the pattern shown in Figure 5.
As the model plots suggest, both antennas have nearly identical performance. Success at last! At least on paper minus any interactions and interfering structures such as air conditioning ducts and electrical wiring. Installing two antennas with separate feeds is easy to control with a remote antenna switch. I avoided the need for relays to shorten elements on 17 meters in order to work on 15 meters. I did not want to use relays because of the prospect of RFI causing them to trip, and the need for extra wires from my shack plus ferrite cores for RFI suppression. Now on to the fun part – BUILD IT.
On July 10, N1FD members gathered in Cornish, NH to activate the Saint-Gaudens National Historical Site as part of the ARRL’s year-long National Parks On The Air (NPOTA) event which is celebrating the 100th anniversary of the National Park Service. We almost canceled it due to a prediction of thunderstorms, but the weather changed to merely intermittent showers, which we didn’t let get in our way.
While the rain was still very light, the advance crew was able to set up the canopy that was last used as the food tent during our recent Field Day operation. It was more than adequate to keep the 100W station and a handful of club members dry throughout the day. The site was on the edge of the meadow (a/k/a the reserve parking area) near the entrance to the Ravine Trail which was furthest from the buildings.
With the next carload of club members and a pneumatic launcher, we were able to put a line over the branch of a tree along the edge of the meadow and use it to hoist up a 20m dipole in an inverted “V” configuration. It only had to be lowered and raised a couple of times to tune it, and we got it right on the mark using an antenna analyzer.
A small, quiet generator was also set up on the edge of the field to provide power. This 20m antenna and generator were used on the 100W station, an IC-7300.
A second station, Fred AB1OC’s 500W mobile station, was parked midway across the field towards the road and operated on 40m. I don’t know how many NPOTA activations have had multiple stations running at once, but a number of hams worked us on both bands.
Unlike our visits earlier in the year, park operations were in full swing for the season. All of the buildings were open to visitors. The park’s Resident Artist for this summer was working on a clay original to later be cast in bronze, and he paused to talk to us about his work. Club members were able to explore other modern sculpture, and also the sculpture by Augustus Saint-Gaudens, that is on exhibit throughout the grounds. A number of members walked the Ravine Trail, which descended into a deep ravine (what did you expect?) to a stream and a swimming hole used by Augustus Saint-Gaudens and his family and others who worked at the studios. People were also able to enjoy a bit of the Sunday afternoon concert.
Not too far from where our 20-meter station was, Mike K1WVO spotted a tiny salamander, a Red Eft, crawling across the forest floor. I’m not sure, but I suspect that a few Pokémon were also spotted in the park!
We also had some special visitors: a ham from California whose daughter worked at the Marsh-Billings-Rockefeller National Historical Park across the river in Vermont, and a local ham who worked us and then drove over for an eyeball QSO.
The rain continued off and on throughout the day, but it was never heavy — certainly not heavy enough to dampen the spirits of the Nashua ARC members who were too busy making or helping to log QSOs to notice it. The group logged a total of 528 QSOs in a little over 4 hours! At the end of the day, the equipment was quickly broken down and packed up, just in time for the rain to completely stop and the skies to clear for a pleasant drive home.
We’re hoping that you and your family can join us for the next activation of this park on August 7!
We took turns operating as two person teams with an operator and a logger. The IC-7000 radio which we use in our Mobile HF station is easily accessible for connection and we brought a laptop running N1MM+ which we connected to the radio. This made logging accurate and easy. We made a little over 210 QSOs in about 2 1/2 hours in Marsh-Billings-Rockefeller on Saturday.
We arrived early on Sunday and began our operation by setting up and tuning a 20m Inverted-V antenna for our portable station. We were able to get the feed point of this antenna up higher (about 35 feet) this time and the antenna performed better as a result.
We setup our 20m portable station in a shady spot at the bottom of the park’s meadow. This gave us a nice view while operating.
We used our 20m portable setup which is based upon the 100w Icom IC-7300 again for our second activation and it worked very well. We had a laptop computer running N1MM+ for logging.
The 20m portable station tent was our main “hang out” during our NPOTA activation on Sunday.
We also had our Mobile HF station at Saint-Gaudens and we operated it on 40m. We were QRO at 500w from the Mobile.
We used the new bandpass filters from DXEngineering on both the 40m Mobile HF and 20m Portable stations. These filters have very low passband loss and very good filtering characteristics. We had no problems with interference between our 20m and 40m stations during our activations.
The park staff rolled out the red carpet for us during both of our NPOTA activations. They displayed our signage and shared the information that we provided about the NPOTA program and our club. They really made us feel at home in the park.
There was a large crowd of visitors at the park during our activation. The combination of great weather and live music was a huge draw for folks. This gave our club and our NPOTA activation some nice public exposure.
Saint-Gaudens was a renowned culture in his time and there are many impressive pieces of sculpture on the park grounds. The park recently commissioned this impressive sculpture of Abraham Lincoln which has become one of their centerpiece works in the park.
The park has many beautiful gardens and they offer a wonderful set of surroundings for the sculptures in the park.
This is my personal favorite spot in the park – a Birch tree-lined walkway!
Our NPOTA operations kept us pretty busy all afternoon on Sunday. We operated as two person teams – an operator and a logger. This gave more of us a chance to operate and the teamwork made it easier to handle the steady stream of callers.
I got a chance to operate both the mobile and portable stations. It was great fun handling our contacts with NS60!
It seems that every Amateur Radio operation that I have the pleasure to be part of manages to hand our a nice surprise or two. This one was not an exception. I worked a local HAM, Jeff Katchen WB2NWR, in Cornish, NH which is very near the park. He came by afterward to visit and share his QSL card and a nice eyeball QSO!
Our operation was a lot of fun – a success by all measures. We made a total of 570+ QSOs between our activations on Friday and Saturday.
There was some discussion at the end of the day on Sunday about doing one more NPOTA activation this year. Our final one would be a high-power operation with both stations running QRO 500w! We will discuss this at an upcoming club meeting and we’ll certainly do a third activation if there are enough interest and support.
We took a lot of nice pictures between this last and our previous activations. You can look at them in the gallery which follows.