Building a 40m Delta Loop Antenna


40m Delta Loop Antenna

40m Delta Loop Antenna

Several members of the Nashua Area Radio Club recently got together to help one of our members, Ralph N1UH, put up a 40m Delta Loop antenna. Delta loop antennas are some of the best performing wire antennas and have the advantage that they can be easily supported via a single elevated mounting point such as a mast or tall tree.

40m Delta Loop EZNEC Model

40m Delta Loop EZNEC Model

The location that Ralph choose for his 40m Delta Loop already had a radial field under it and we decided to take advantage of this to try to improve ground quality under the antenna. He built a detailed EZNEC model of the planned antenna and radial field under it to evaluate the best approach to the design. The antenna was modeled and build with its apex around 50 ft and designs resulting in Horizontal Polarization  (feed point in the center of the bottom leg) and Vertical Polarization (feed point 1/4 wavelength down a vertical leg) were considered.

40m Vertically Polarized Delta Loop Pattern

40m Vertically Polarized Delta Loop Pattern

The graphic above shows the EZNEC modeling result for the Vertically Polarized 40m Delta Loop. This design tends to concentrate the radiated energy at the lower takeoff angles which optimizes the antenna for long DX contacts.

40m Horizontally Polarized Delta Loop Pattern

40m Horizontally Polarized Delta Loop Pattern

This graphic shows the modeled pattern when the antenna is fed to create Horizontal Polarization. On first look, one might conclude that this version of the antenna would only be useful for short-range communications. The point to consider here is that the Horizontally Polarized version of the antenna has much higher overall gain.

40m Delta Loop Gain Comparison

40m Delta Loop Gain Comparisons

The table above helps to better understand the real difference in performance between the two versions of the 40m Delta Loop. Columns 2 – 4 compare the gain of the two versions of the antenna at various elevation angles. We can see that the Horizontally Polarized version of our 40m Delta Loop has higher gain down to elevation angles of about 20 degrees. At lower elevation angles, the Vertically Polarized version has an advantage. Also note that both antennas begin to exhibit less than -1.0 dBi of “gain” at angles below 10 degrees of elevation. The net of this is that the Vertically Polarized antenna does have an advantage for DX signals which arrive at low angles in the 20 – 10 degree range. Such low angles would be typical for very long DX contacts or in conditions of marginal propagation which might occur toward the bottom of the sunspot cycle. For many typical DX contacts (ex. DX contacts with Europe from here in New England) which would have arrival angles in the 20 – 30 degree range, the Horizontally Polarized version of the antenna will probably perform better. Ralph lives in a residential neighborhood with many potential noise sources close by; most of which will tend to be vertically polarized. The Horizontally Polarized version of the antenna will be less sensitive to the local noise sources which gives it a further advantage in this situation.

It’s also interesting to note the effect of the radial field under the antenna in the table above. The benefit of radials is pretty limited in the Vertically Polarized configuration averaging less that 0.5 dB. The gain from the radials is more significant in the Horizontal configuration averaging close to 1.5 dB. This is enough to expose an addition “layer” of weaker stations.

40m Horizontally Polarized Delta Loop Azimuth Pattern

40m Horizontally Polarized Delta Loop Azimuth Pattern

There is a common misconception that a Delta Loop Antenna is directional towards the open side of the loop. This is not the case at typical heights above ground. The plot above shows the pattern of the Horizontally Polarized version of the loop to be omnidirectional.

40m Vertically Polarized Delta Loop Azimuth Pattern

40m Vertically Polarized Delta Loop Azimuth Pattern

The graphic above shows the equivalent pattern for the Vertically Polarized version. Note that this antenna is actually slightly directional off the ends of the antenna, not towards to open side of the loop. This is a result of the fact that the two vertical legs of the Vertically Polarized Delta Loop antenna behave somewhat like two independent vertical antennas in a phased array.

The net of all of this analysis was that Ralph decided to build the Horizontally Polarized version of the 40m Delta Loop.

Finished Radial Field Under The Antenna

Finished Radial Field Under The Antenna

The first step in constructing the antenna system was to expand the existing radial field under the antenna.  We next put up a 50 ft guyed mast to support the apex of the loop. The result is shown above.

Feed Point and Balun on Mast

Feed Point and Balun on Mast

The antenna’s bottom wire element is about 10 ft above the ground and the bottom corners are anchored to the ground via Dacron guy ropes. After trimming the antenna to be resonant in the center of the 40m band, we found the final impedance to be around 80 ohms. We used a custom 1.5:1 Balun from Balun Designs to create a 50 ohm match at the Delta Loop’s feed point. The picture above shows the Balun mounted on the mast about 10 ft up from the ground. The antenna’s 2:1 SWR bandwidth with the Balun covers the entire 40m band. The antenna is fed with a relative short run of LMR-400UF coax inside underground conduit.

40m Delta Loop in use with FlexRadio-6700 SDR

40m Delta Loop in use with FlexRadio 6700 SDR

The final step of the project was to hook up the completed 40m Delta Loop system to Ralph’s FlexRadio 6700 SDR. We made several QSOs with the new antenna to verify that its performance across the band was as expected. Ralph has been receiving good signal reports with his new antenna further confirming that it is performing as expected. I have built several 40m Delta Loops at my home QTH at as part of our club’s 2015 Field Day Operation this past year. All have been good performers.

– Fred (AB1OC)

2015 Nashua Area Radio Club Field Day Recap


We had the opportunity to be part of the Nashua Area Radio Club’s 2015 Field Day Operation. Ed, K2TE was our incident commander and he helped to club to put together a great Field Day Operation. We operated under our club callsign, N1FD as 8A. John, W1MBG put together the video above which is a really nice recap of our operation.

Field Day Tower and Beams

Field Day Tower and Beams

The club was very active in WRTC 2014 and, as a result, was able to purchase several of the tower and station kits from the WRTC operation. The heart of our Field Day antenna system was built around two of these towers. One was used for CW and 6m and the other was used for SSB. Both towers had tri-band beams and we used Triplexers and Filters to allow our stations on 20m, 15m and 10m to share the beams on each tower. The towers got us a long way towards our status as an 8A operation.

Wire Antenna Construction

Wire Antenna Construction

My role in the setup part of our Field Day operation was to build our wire antennas. We began with a class covering how to build and tune Delta Loop antennas and we used the newly gained information from our class to build 40m and 80m delta loops at our Field Day site. We also put up a 75m inverted-V antenna in one of the tall trees at our site.

Operating Tents

Operating Tents

We made good use of our WRTC station kits and other gear that our members brought to setup comfortable tents to operate from as well as a public information tent and a food tent.

Operators For The Nashua Area Radio Club

Some Of Our Operators For The Nashua Area Radio Club

Despite the rainy weather on Saturday evening and Sunday, we all stayed comfortable and dry. Shown above is Dave, N1RF, Mike, K1WVO and Mike, K1HIF in our 40m SSB tent.

Field Day 20m SSB Station

Field Day 20m SSB Station

John, W1MBG and I shared a tent which we used for both 10m and 20m SSB operations. The picture above shows our 20m station which was built around an Elecraft KX3 with a PX3 Panadapter and 100w outboard amplifier.

Young Person Operating During field Day

Mikayla Operating With Her Dad During Field Day

Our club has been doing a great deal of work on bringing young people and other new HAMs into the hobby via license classes, outreach to schools and other activities. We carried this work into our Field Day operations with a GOTA station and lots of opportunities for new HAMs and young people to get on the air. Shown above is Wayne, AA9DY helping his daughter Mikayla to make some contacts on 20m SSB phone.

Field Day Feast

Field Day Feast

Anita, AB1QB made us great meals and snacks during our Field Day operation. The food provided all of us a great opportunity to take a break from operating and enjoy each other’s company. Anita and John, W1SMN organized our public information and outreach activities which were very successful. we had over 30 visitors from the general public during our operation this year.

We all had a great time during Field Day this year and we’re looking forward to doing it again next year.

– Fred (AB1OC)

 

 

 

Mobile HF And Station Building Presentations At The 2015 Boxboro Hamfest


Saturday Forum Schedule

2015 Boxboro Hamfest – Saturday Forum Schedule

It is once again time for the New England Regional Hamfest. The convention will be held in Boxboro, Massachusetts this weekend and will feature a great presentation and forum schedule, a large vendor exhibit area and a HAM Flea Market.

Sunday Forum Schedule

2015 Boxboro Hamfest – Sunday Forum Schedule

We will be doing presentations at Boxboro on two of the most popular topics that we write about here on our Blog – Mobile HF Station Building and Amateur Radio Station Design and Construction.

Mobile HF Presentation

Mobile HF  Station Building and Operation Presentation

Our articles on Mobile HF Station Building have become quite popular and we will be doing a presentation on this topic on Saturday at 11 am local time.

Mobile HF Car Installation

Mobile HF Car Installation

We continue to add new material to our presentations and the Mobile HF talk will include new material on a Dave, N1RF’s recent installation of a top-notch mobile HF station in a car.

Station Building Presentation

Amateur Radio Station Design and Construction Presentation

We will also be doing a talk on Amateur Radio Station Design and Construction at 4 pm on Saturday.

Remote Operation Preview

Remote Operation Preview

We constantly update the material in this presentation and this version will include a preview of a new project to enhance our station – a Remote Operating Gateway based upon a FlexRadio 6000 Series SDR.

We hope to see many of our friends and readers in the region at Boxboro this year. If you have a minute, stop by the forums and say hello.

– Fred (AB1OC)

2015 13 Colonies Special Event Operations Summary


Summary of K2K NH 2015 Operations

Summary of K2K NH 2015 Operations

Well, the 2015 Thirteen Colonies Special Event is history and K2K New Hampshire had another record year making 10,292 contacts during the event. We had a great team of operators this year – Layne AE1N, Ed K2TE, Dennis K1LGQ, Dave KM3T, Anita AB1QB and myself.

K2K NH Contact Details for 2015

K2K NH Contact Details for 2015

We improved our contribution to the event in almost every area this year. We had a great balance between SSB and CW with some 28% of our contacts using CW! We also had a better balance of contacts outside NA – 15% being DX. Another interesting stat is that we worked about 1/2 of all of the Counties in the United States.

Interesting K2K NH Contacts in 2015

Interesting K2K NH Contacts in 2015

Operating in a major Special Event like 13 Colonies always produces some interesting contacts. We worked some pretty interesting DX stations including a QRP to QRP CW contact between New Hampshire and Japan. You can see from the concentration of our contacts around the world in the map above (click to enlarge).

2015 Thirteen Colonies QSL Cards

2015 Thirteen Colonies QSL Cards

In addition to the really nice certificate for working the event, there is a very nice collection of QSL cards available for working each of the Thirteen Colonies and the two bonus stations. Many states, including New Hampshire, redesigned their QSL cards this year which adds to the fun of collecting them. You can find QSL information for the event here.

K2K New Hampshire QSL!

K2K New Hampshire QSL!

The QSLs are rolling in! We are using the DXLab Suite to automate the printing/QSL’ing for K2K New Hampshire this year and this allows us to keep up with the incoming QSL requests on a daily basis. We are also providing QSL’ing via LoTW, eQSL, and ClubLog.

I hope that everyone enjoyed the event! We certainly did. We’re looking forward to seeing everyone again next year!

– Fred (K2K/AB1OC)

The 2015 13 Colonies Special Event Begins Today!


2015 K2K QSL Card

2015 K2K QSL Card

The 2015 Thirteen Colonies Special Event begins today! There are stations in each of the states that grew from the original Thirteen Colonies plus two bonus stations – WM3PEN in Philadelphia, PA and a GB13COL in the United Kingdom. We have redesigned the K2K NH QSL card this year as part of the 2015 event theme – Patriots and Founders of the Republic. we have a great team of operators for the New Hampshire Colony this year. You can check them out here. You can find where the event stations are operating by using the 13 Colonies Spotting cluster.

2015 13 Colonies Special Event Certificate

2015 13 Colonies Special Event Certificate

In addition to collecting the QSL cards from each of the state and bonus special event stations, there is a very nice certificate available for working one or more of the 13 Colonies stations. See the event website for details.

I hope that our readers will take some time and participate in the 13 Colonies Special Event this year. Its great fun for all involved. Happy July 4th United States of America!

– Fred (AB1OC)

2015 Field Day Station Test


Field Day QTH

Field Day QTH

It’s almost time for the 2015 Field Day Event and we’ve been in high gear getting ready. Anita, AB1QB and I will be operating with the Nashua Area Radio Club, N1FD this year. The club was very active in WRT2014 and we were able to purchase several of the WRTC station and tower kits from that effort. I will be operating the 20m SSB station for Field Day and Anita and I decided to setup our station kit in our backyard last weekend to verify that all of our equipment was ready and in good working order. The first step was to pitch the wall tent from the WRTC kit. The tent and the associated tables/chairs can comfortably hold 3 – 4 people.

Field Data SSB Station Test

Field Data SSB Station Test

I will be using our Elecraft KX3 Transceiver again this year. We’ve added an outboard KXPA100 100w Amplifier to bring the station up to 100w and Elecraft’s very nice PX3 Panadapter. The combination makes a great 100W Field Day Station.

Elecraft KX3 Field Day Station

Elecraft KX3 Field Day Station

The picture above is a closer view of the setup. The KXPA100 Amplifier and the PX3 Panadapter are fully integrated with the KX3 and the combination creates a 100W transceiver with a useful Panadapter. The Panadapter should be helpful for Search and Pounce operation during Field Day. I’ve also added a Behringer HA400 four channel headphone amplifier (the unit on the right on top of the power supply) to the setup. This enables connection of a total of 4 sets of headphones to the station – one for the operator, one for a logger and two more pairs for folks to listen in on the fun. Our club has been doing a great deal of outreach to encourage new HAMs to join the hobby and I built this setup so that some of the new folks can listen in on our operation more easily. I will be using a Heil Pro 7 headset to operate and we will have 3 sets of Heil Pro Set 3 headphones for others to use. The Heil gear is very comfortable, light weight and sounds great over the air.

N1MM+ Logger

N1MM+ Logger

I will be using the excellent N1MM+ Logger for Field Day this year. It was very easy to setup N1MM+ to work with the KX3. I was also able to use it to trigger the KX3’s voice message memories for calling CQ and for calling in Search and Pounce mode. I am doing an N1MM+ clinic at our final Field Day prep meeting tonight to help others in our club to get going on the N1MM+ logger.

Generator Test

Generator Test

One of the many great aspects of Field Day is that it results in a test of one’s emergency equipment and operating skills each year. Our club has a large generator and power distribution system that we all share for Field Day so I used our station test session as a reason to get my smaller generators out for a test run. We have a pair of Honda EU2000 generators which can be used together to generate quite a bit of power. Here’s one of them in use during our station test.

Our club has quite a bit of antenna equipment and we will be putting up two 40 ft towers and tri-band beams with Triplexes and Filters for our 20m, 15m and 10m SSB and CW stations. I’ve built a 40m Delta Loop for our club to use for 40m SSB and we’ll be putting up 40m and 80m inverted-V and dipole antennas to cover those bands. I plan to do another post after Field Day is done on the setup of our antennas and the N1FD operation. I hope to work some of our readers on the air during Field Day this year.

– Fred (AB1OC)

An Introduction To Amateur Radio At The Academy For Science And Design


SPARK Day At The Academy For Science And Design

SPARK Day At The Academy For Science And Design

John Keslo, W1MBG and I (both members of the Nashua Area Radio Club) recently had the chance to visit the Academy for Science and Design (ASD) in Nashua, New Hampshire to provide an Introduction to Amateur Radio for the students there. ASD’s goal is to be a world-class school that specializes in science, engineering, mathematics and design for students in grades 6-12. ASD periodically holds SPARK (Symposium Promoting Advancement of Real-world Knowledge) conferences, which enable ASD students to learn about areas which might help them to develop careers in Science, Technology, Engineering and/or Math (STEM). The students at ASD are extremely bright and are highly motivated to develop STEM careers. We had about 45 students elect to attend the two sessions that John and I presented.

Introduction To Amateur Radio Video

Introduction To Amateur Radio Video

After some introductions and a little time spent by John and me to explain how Amateur Radio has led each of us to careers in Engineering, we showed the group a video entitled Discovering Amateur Radio. This video provides an excellent introduction to Amateur Radio and we have used it successfully in many settings include the Nashua Area Radio Club sponsored Technician License Training Classes that we have been doing.

Demonstration Station Setup

Demonstration Station Setup

John and I setup a portable HF Radio Station at the school to enable us to demonstrate Amateur Radio to the students. We used an Elecraft KX3 Transceiver with an outboard PX3 Pan Adapter and a KPA100 Amplifier (100W).

20m Vertical Antennas Using Buddi-pole Kit

20m Vertical Antennas Using Buddipole Kit

We also built a 20m Vertical Antenna with elevated radials outside the school. We used the Buddipole Antenna System to build this very effective antenna for the demonstration.

Amateur Radio Demonstration

Amateur Radio Demonstration

The students were very interested in the radio setup and antennas and asked quite a few questions about both the setup and how they could get involved in Amateur Radio. John and I were able to get on the air and make several contacts. The operators that we contacted spoke with some of the kids and shared their experiences with Amateur Radio which made the session great fun for everyone involved.

Maggie Hassan, NH State Governor, Visiting ASD SPARK

Maggie Hassan, NH State Governor, Visiting ASD SPARK

We were honored to have the Governor of the State of NH, Maggie Hassan visit our ASD SPARK session. The picture above shows John explaining  Amateur Radio and how we were using it to help forward the goals of ASD’s students.

It was very rewarding and a lot of fun for John and me to participate in SPARK day at the Nashua Academy for Science and Design. I hope the we’ll have a chance to do this again in the future.

– Fred (AB1OC)