Software Defined Radio/Remote Operating Gateway Part 3 – On The Air Remote!


Remote Operating Setup In Our Home Office

Remote Operating Setup In Our Home Office

In the previous articles is this series, we explained how we integrated a FlexRadio-6700 Software Defined Radio (SDR) into our station and how we used it as a platform to build the Remote Operating Gateway for our station. The project has turned out to be somewhat involved so we will be providing a series of articles to explain what we did:

With all of the hardware and software installed and the integration steps complete, we will  show some examples of using our remote operating setup on the air in this article. The first set of operating examples were made using the Remote Operating Client PC in our Home Office. This system is shown in the picture above.

Working The VK9WA DXpedition - Left Monitor

Working The VK9WA DXpedition – Left Monitor

We were able to make several contacts with the VK9WA DXpedition to Willis Island using our remote operating setup. The picture above provides a closer look at how we setup our Remote Client PC to work VK9WA (you can click on the pictures here to see a larger view). We just completed a CW contact with the VK9WA DXpedition on 40m and you can see that we have the QSO logged in DXLab’s DXKeeper. We used CW Skimmer to help determine where the operator was listening (more on this in a bit). We also used our Elecraft KPA500 Amplifier to make it a little easier to break through the pileup.

Working The VK9WA DXpedition - Right Monitor

Working The VK9WA DXpedition – Right Monitor

The picture above shows a better view of the second monitor on our Remote Client PC. SmartSDR is running to control our FlexRadio-6700 SDR and it is set up for split operation in CW mode on the 40m band. We also have DXLab’s DXView running and we used it to point our antennas to the short path heading for the VK9WA DXpedition. Finally, we used DXLab’s WinWarbler to remotely key the Winkeyer connected to our SDR in the shack to make the actual contact.

VK9WA DXpedition 30m Pileup Viewed From CW Skimmer

The video above shows the VK9WA DXpedition operating split in CW mode on the 30m band. Note how CW Skimmer allows us to see exactly where  the operator is listening (the VK9WA operator’s signal is the green bar at the bottom and the stations being worked can be seen sending a “599” near the top). You can see many of the folks trying to work the VK9WA DXpedition move near the last station that is worked in the pileup video.

VK9WA DXpedition 30m Pileup  Viewed From SmartSDR

The next video shows the VK9WA pileup in the SmartSDR application which controls the radio. This video provides a closer look at how SmartSDR is set up for split operation. Can you find the station that the VK9WA operator worked?  It is not quite in Slice Receiver B’s passband.

Laptop Remote Operating Client

Laptop Remote Operating Client

We also configured our Laptop PC to be a Remote Operating Client for our station. Our Bose SoundLink Bluetooth Headset is used to as both a wireless microphone and headphones with this system. Our Laptop Client PC can be used from any location on our property via the WiFi Wireless extension of our Home Network.

Window Arrangement For remote Operating From Laptop

Window Arrangement For remote Operating From Laptop

Since our Laptop PC has limited screen space, we created a configuration of overlapping windows to provide access to SmartSDR, key elements of the DXLab Suite and the applications which control/monitor our KPA500 Amplifier and Antennas. Each window is arranged so that a portion of it is always visible so that we can click on any required window to bring it forward when we need to use it.

Operating From Our Remote Laptop Client – A 20m SSB QSO

The video above shows a QSO that we made with AD0PY, David and his friend Daniel in Missouri, USA. We used the FlexRadio-6700 SDR/SmartSDR combination in VOX mode to make transmit keying simpler. At the beginning of the QSO, we  turned out antennas to point to AD0PY. Also note the operation of the KPA500 Amplifier when we transmit in the video. The QSO is logged in DXLab’s DXKeeper at the end of the contact in the usual way. Its fun to make casual contacts this way!

As you can see from this post, there is very little difference when we operate our station remotely or from our shack. This was an important goal that shaped the design of our Remote Operating Gateway and Client PC setup. Our next post will provide some details on how we setup the CW Skimmer and Digital Mode (RTTY, PSK and JT65/JT9) software to work on our Remote PC Clients.

– Fred (AB1OC)

Software Defined Radio/Remote Operating Gateway Part 2 – Client/Server Setup And Software


 

Remote Operating Gateway Client/Server Architecture

Remote Operating Gateway Client/Server Architecture

The next step in our Software Defined Radio/Remote Operating Project was to build a Remote Operating Gateway System in our shack and setup Client PCs to operate our station remotely. In a previous article, we explained how we integrated a FlexRadio 6700 Software Defined Radio (SDR) into our station to create a platform to build our remote operating project around. The project has turned out to be somewhat involved so we will be providing a series of articles to explain what we did:

In this article, we will explain the additional hardware and software that we used to enable remote operating as well as some additional equipment we added to our Client PCs that we use to operate our station remotely. The reader may want to refer to the picture above as you browse this article to better understand how the parts in our remote operating setup fit together. You can click on any of the pictures here on our blog to see a larger, easier to read version of them.

SmartSDR Software

SmartSDR Software Operating With A FlexRadio 6700 SDR

FlexRadio’s SmartSDR Software handles operating the SDR remotely. At the present state of maturity, SmartSDR can operate over a wired or wireless Ethernet LAN connection. At present, both SmartSDR and the FlexRadio-6xxx hardware must be on the same sub-network to function properly. FlexRadio has indicated that they plan to enable SmartSDR operation over wide-area broadband internet connections in the future. The design that we chose for our Remote Operating Gateway and Client PCs will allow operation of our entire station over the internet when SmartSDR is capable of fully supporting this. SmartSDR handles remoting of audio (microphone and speakers/headphones) as well as CW keying over our Home Network (more on this later) as well as control of the radio. With these key functions taken care of, we need to also remote the following functions of our station to fully support remote operation:

Remote control of equipment power is particularly important to provide a means to reset/restart equipment remotely as well as a means to shut down the Transmitter remotely.

Remote GW Control Stack - Antenna, Power and Monitoring

Remote Gateway Control Stack – Antenna, Power and Monitoring

Remote control of power for the components in our Remote Operating Setup is handled by a RIGRunner 4005i power control device. This unit provides remote power control over a network for up to 5 separate groups of devices. It also provides voltage/current monitoring and solid state over-current protection as well.

RIGRunner Remote Power Control Setup

RIGRunner Remote Power Control Setup

The figure above shows how we setup our RIGRunner 4005i. The device is controlled over our Home Network via a standard Web Browser. As you can see from the picture above, this devices lets us remotely control power to all of the devices in our Remote Operating Setup.

Remote Control Relay Unit

Remote Control Relay Unit

The FlexRadio-6700 SDR requires some additional power control handling. Simply removing and applying power to the FlexRadio-6700 SDR will reset the radio and leave it in a power off state. The FlexRadio-6700 SDR does have a remote power control input which can be controlled via a relay closure. We used a microbit Webswitch 1216H device to provide a remotely controlled relay closure to control the power off/on for the FlexRadio-6700 SDR.

Flex-6700 On/Off Control Via microbit Webswitch

Flex-6700 On/Off Control Via microbit Webswitch

The microbit Webswitch 1216H relay unit is also controlled over our Home Network via a standard Web Browser.

SmartSDR Setup - Tx Keying, Tx Interlock and Remote Power Control

SmartSDR Setup – Remote On/Off Control

The FlexRadio-6700 SDR is configured for remote on/off operation via the Radio Setup dialog in SmartSDR as shown above. A cable is run between the remote power on/off port on the FlexRadio-6700 SDR and the microbit Webswitch 1216H relay unit to complete this part of our Remote Control System.

Beams On Our Tower

Beams On Our Tower

It is also important to have full remote control of our Antennas and Rotators to effectively use our station from outside our shack. Control of our Rotators is accomplished by software which remotes serial COM ports over our Home Network.

Network Serial Port Kit

Network Serial Port Kit

We used the Fabulatech’s Network Serial Port Kit package to remote the serial COM ports used to control the microHAM Station Master Deluxe Antenna Controller, the associated antenna Rotators and the WinKeyer associated with our FlexRadio-6700 SDR. This software runs on both the local Server computer in our shack which hosts the Remote Operating Setup and any Client PCs which are used to operate our station remotely.

microHAM Station Master Deluxe Antenna Control via Teamviewer and Development App

microHAM Station Master Deluxe Development Application Via TeamViewer

There is not currently a production software tool to enable remote control of the microHAM Station Master Deluxe Antenna Controllers which we use in our shack. I am planning to develop our own application to do this in the future. The folks at microHAM have been so kind to provide me with the interface specifications needed to control the Station Master Deluxe Antenna Controller remotely along with a Developer Only test application (shown above) which can be used to understand the microHAM Device Protocol. In the interim, I have been using the microHAM Developer Only application along with the TeamViewer Remote Control Software to control antenna selection remotely and to monitor the position of the current selected rotators.

Shack Remote Operating Gateway Server PC Applications

Shack Remote Operating Gateway Server PC Applications

The remaining software required for remote control of our station is provided by the Elecraft applications which control the KPA500 Amplifier, KAT500 Auto-Tuner, and W2 Wattmeter which are used in our Remote Operating Gateway setup. All of these applications along with the microHAM Developer Only Application for Station Master Deluxe control and the DDUtil Program which interworks the FlexRadio-6700 SDR CAT interface with the Station Master Deluxe (see the previous article in this series) are shown above running on our Shack Server PC. This PC is on at all times and is protected by a Uninterruptible Power System (UPS) to ensure that it runs trouble-free.

Remote Operating PC Client Software Applications

Remote Operating PC Client Software Applications

In addition to FlexRadio SmartSDR, each of the Server Side PC applications has a corresponding Client Side application which is used on the Remote Operating Client PC. Shown above are the three Elecraft Client applications for Amplifier, Auto-Tuner and Wattmeter control and monitoring. The client side Network Serial Port Kit application which replicates the WinKeyer, microHAM Station Master Deluxe and Rotator Control COM ports is also shown.

Heil Microphone And USBQ Adapter

Heil Microphone And USBQ Adapter

The PC in our home office will be a primary remote operating location for our station. Audio quality is important to us and we wanted to ensure that the quality of our audio was just as good operating remotely as it is when we operate from our Shack. To accomplish this, we installed a Heil PR781 Microphone, PL2T Boom and USBQ Adapter/Pre-Amp on our home office PC. The Heil USBQ is a USB sound card and microphone pre-amplifier which connects directly to the PR781 microphone to create a high-quality phone audio source which can be used with the FlexRadio-6700 SDR when operating remotely.

Bose SoundLink BluTooth Headset

Bose SoundLink Bluetooth Headset

The speakers our my home office PC are quite good but there are often times when a set of headphones are needed to hear weak signals. We choose a quality Bluetooth Headset from Bose for this purpose. The Bose SoundLink Headset is light weight, is wireless, has excellent fidelity and includes a very good microphone which can be used as an alternative to the Heil PR781. This headset is also very useful when operating from our Laptop Client PC from noisy locations outside our home (more on this in a future article).

SmartSDR DAX Control Panel

SmartSDR DAX Control Panel

The last pieces of the remote operating system are provided two applications which are part of the SmartSDR software package. The SmartSDR’s DAX Control panel provides remote audio connections for Digital Mode Software and the CW Skimmer decoder. Audio is provided by software “audio cables” for each of the FlexRadio SDR’s Slice Receivers and the active Tx Slice. SmartSDR DAX Audio IQ interfaces are also provided for each of the SDR’s Panadapters which permits software like CW Skimmer to monitor and decode a wide range of frequencies simultaneously.

SmartSDR CAT

SmartSDR CAT

The SmartSDR CAT application provides CAT interfaces on both our Client and Server PCs for applications which need to control or monitor what the FlexRadio-6700 SDR is doing. Many loggers and other applications are beginning to implement direct IP interfaces to the CAT channel of the FlexRadio 6xxx Series SDRs. This approach simplifies interworking between the software and the radio and appears to be more reliable than virtual COM-based CAT interfaces.

Client PC Running SmartSDR And The DXLab Suite

Client PC Running SmartSDR And The DXLab Suite (Home Office)

With all of the above elements in place, any client PC that can access our Home Network can be used to operate our station. The picture above shows SmartSDR and the DXLab Suite running on our Home Office PC. The remote emulations of the Rotator, CAT and Winkeyer interfaces are such that DXLab’s applications can fully operate our station as if they we running in our shack.

Client PC Running SmartSDR And The DXLab Suite - Right Monitor

Client PC Running SmartSDR And The DXLab Suite – Right Monitor

The picture above shows a closer view of my Home Office PC’s Right monitor (click on the picture to enlarge it). SmartSDR is running the upper left corner and I am listening to folks operate in the 2015 CQ WW DX CW Contest. The SDR is set on the 20m band and I have the CW Keyer which is built into SmartSDR running. The DAX Control Panel is running on the lower right corner of the screen and its setup for use with the CW Skimmer decoder. DXLab’s WinWarbler is running (top-center) which enables me to use the WinKeyer in the shack to send CW as well via the remote COM port associated with the WinKeyer. Below WinWarbler is the microHAM Developer Only application (accessed remotely via a TeamViewer connection to the Shack Server PC) which shows that I have both of our SteppIR DB36 Yagis are selected as a stack and pointed towards Europe. DXLab’s DXView Rotator Control application is running in the center-bottom of the screen so that we can turn our Yagis towards other parts of the world (rotators are controlled via another remote COM port). Finally, the client KPA500 Amplifier control application is running in the lower left corner to control the amplifier and to monitor the power out and SWR seen by the amplifier being used to operate remotely.

Client PC Running SmartSDR And The DXLab Suite - Left Monitor

Client PC Running SmartSDR And The DXLab Suite – Left Monitor

The picture above shows a closer view of the left monitor. DXLab’s logger, DXKeeper is running at the top/center of the screen. Below it is DXLab’s SpotCollector application which is monitoring spots of the many CW stations around the world that are operating in the contest. DXLab’s Commander applications is running in the lower-right corner of the screen and is monitoring the FlexRadio-6700 SDR’s slice Tx/Rx frequency as well as providing a control interface of the SDR to the rest of the DXLab Suite (via SmartSDR CAT). The Elecraft W2 Wattmeter client control application is just above commander. The W2 Wattmeter client application provides higher resolution power out and SWR monitoring for the remote setup. Bottom-center is DXLab’s Launcher application and just to the left of that is the KAT500 Auto-Tuner Client Control application. Finally, CW Skimmer is running on the left side of the screen.

CW Skimmer Operating Remotely

CW Skimmer Operating Remotely

As you can see, CW Skimmer is decoding a wide range of frequencies in the 20m CW sub-band. It is receiving its audio in IQ format via the SmartSDR DAX application. It is great fun to operate CW this way and I am finding myself making a lot more CW contacts now that I have the remote operating setup in my office.

The next post will provide some samples of remote operation in the form of videos. I will also share some information on setting up a Remote Operating Client on a laptop where screen space is more limited. We plan to take a trip outside our house to operate our station over the Internet and we plan to share information on how that is done. We will also provide future articles on how to setup CW Skimmer and Digital Modes (RTTY, PSK and JT65/JT9) on the HF Bands and use them remotely.

For now, we are really enjoying the freedom to operate our station remotely!

– Fred (AB1OC)

Software Defined Radio/Remote Operating Gateway Part 1 – System Design And Hardware Installation


Flex-6700 Software Defined Radio Stack

Flex-6700 Software Defined Radio And Remote Operating Gateway

We’ve been planning to add a remote operating capability to our station for some time now. We also did some previous work with a FlexRadio Software Defined Radio (SDR) in our station and we felt that an SDR would be a good platform to build a remote operating project around. We decided to combine our remote operating goals with a next generation SDR upgrade (a FlexRadio-6700) for our station. This project has turned out to be somewhat involved so we will be providing a series of articles to explain what we did:

We will be tackling our goals of building a Remote Operating Gateway (GW) in two stages. Stage 1 will focus on operating our station from other rooms in our house (our Home Offices are prime locations for this). Stage 2 will involve operating our station “On The Go” from anywhere in the world that has sufficient Internet Access is available. We also want to enable full control of our station when operating remotely including:

  • Use of our Amplifier
  • Antenna Selection
  • Rotator Control
  • Equipment Power Monitoring and Management

We also use a microHAM station control system and contesting equipment and we want to fully integrate our new Flex-6700 SDR with this gear. Our Flex-6700 uses a dedicated Microphone to avoid some audio integration issues that we encountered between the Flex-6700 and the microHAM MK2R+ that we use in our station.

SDR/Remote Operating Gateway Architecture

Flex-6700 SDR/Remote Operating Gateway Architecture

The first step in this project was to develop a system design (pictured above). We opted for an architecture which uses the Flex SDR as a third radio in Anita’s Operating Position. Her position is now an SO2R setup with a Yaesu FTdx5000 as the primary radio and a choice of either an Icom IC-7600 or the Flex-6700 SDR as the second active radio.

Elecraft KPA500 Amplifier and KAT500 Auto Tuner

Elecraft KPA500 Amplifier and KAT500 Auto Tuner

Elecraft W2 Watt Meter

Elecraft W2 Watt Meter

FilterMax IV Automated Band Pass Filter

FilterMax IV Automated Band Pass Filter

The Flex-6700 SDR has an associated Elecraft KPA-500W Amplifier/KAT500 Auto Tuner combination, an Elecraft W2 Wattmeter, an automated band pass filtering via an Array Solutions FilterMax IV and a dedicated microHAM Station Master Deluxe (SMD) Antenna Controller. The Elecraft components are good choices for our remote operating project because they all have applications which enable them to be controlled and monitored over a network (more on this later in this series of articles).

Station Antenna System

Out Station’s Antenna System

The additional microHAM SMD allows the Flex-6700 SDR to have full access to and control over our entire antenna system and associated rotators.

K1EL WinKeyer

K1EL WinKeyer

Our setup also includes a K1EL WinKeyer to enable computer controlled CW keying of the Flex-6700 SDR. This device is relatively inexpensive in kit form and was fun to put together. We have a Bencher Iambic Paddle connected to the WinKeyer for in-shack CW operation.

SDR microHAM Integration

SDR microHAM Integration

The diagram above shows the details of the device interconnections which make up the SDR Radio System. The microHAM SMD Antenna Controller requires a serial CAT interface to its host Flex-6700 SDR to determine what band and frequency the SDR is on. The Flex-6700 SDR does not provide such an interface directly but it does create CAT control virtual ports on a host Personal Computer (PC).

DDUtil Setup - SDR Virtual CAT Access

DDUtil Setup – SDR Virtual CAT Access

DDUtil Setup - Bridging Physical Serial Port To SMD

DDUtil Setup – Bridging Physical Serial Port To SMD

To solve this problem, we used an application called DDUtil to bridge the derived CAT port associated with the SDR to a physical serial port on the PC. The PC’s physical port is then connected to the microHAM SMD associated with the Flex-6700 SDR. The pictures above show how DDUtil is set up to do this.

Station COM Port Configuration

Station COM Port Configuration

The microHAM gear, WinKeyer, Rotators, Radio CAT Interfaces, Amplifier/Auto Tuner Interfaces, etc. all use serial or COM ports on a host PC for control. It’s also true that many loggers have trouble with accessing serial ports above COM16. All of this requires a carefully developed COM port allocation plan for a complex station like ours. The figure above shows this part of our design.

A-B Switching Design For Radio Port 4

A-B Switching Design For Radio Port 4

microHAM Bus Expansion And Antenna Switching Gear

microHAM Bus Expansion And Antenna Switching Gear

The last part of the hardware puzzle required to integrate the SDR into our station was the installation of a second microHAM uLink Bus Hub, microHAM Relay 10 Control Box and an A/B antenna switch which is controlled by the microHAM SMDs. This allows the 4th radio port on our antenna switching matrix to be shared between the Icom IC-7600 and the Flex-6700 SDR.

microHAM Configuration For SDR Station Master Deluxe

microHAM Configuration For SDR Station Master Deluxe

The last step in the integration of the Flex-6700 SDR was to configure the microHAM system for the new equipment. This involves adding SMD #5 to the microHAM system and configuring it (and the rest of the system) to know about the Flex-6700 SDR, associated amplifier and its interconnections to the rest of the system.

SmartSDR Software

SmartSDR Software

The Flex-6700 SDR Hardware is controlled and operated via FlexRadio’s SmartSDR Application over a network. We have 1 Gbps wired and an 802.11 b/g/n Wireless Ethernet systems in our how and the SmartSDR/Flex-6700 SDR combination works well over either network. The software based approach used with most SDR allows new features to be added to the radio via software upgrades.

SmartSDR Setup - Tx Keying And Interlock

SmartSDR Setup – Tx Keying And Interlock

It is very important to prevent the Flex-6700 SDR and the associated Amplifier from keying up when the antennas in our station are being switched or are being tuned. The screenshot above shows the configuration of SmartSDR to enable the keying and interlock interfaces between the Flex-6700 SDR and its associated microHAM Station Master Deluxe Antenna Controller to implement these functions. This setup enables the Tx Keying and Tx Inhibit interfaces between the Flex-6700 SDR and the microHAM Station Master Deluxe to work properly to key all of the equipment in the setup (SDR, Amplifier, active Rx antennas, etc.) and to lock out keying when antennas are being switched or when one of our SteppIR antennas are tuning.

Flex-6700 SDR With CW Skimmer

We will cover some additional software and integration steps to realize our Remote Operating goals. For now, check out the above video to see how the system performs. This video was recorded using our Flex-6700 SDR and CW Skimmer during the 2015 ARRL CW Sweepstakes Contest. We are really enjoying operating in CW mode with the new SDR setup!

– Fred (AB1OC)

A Milestone Contact – Working Mt. Athos (Last New One In Europe)


Monk Apollo

Monk Apollo, SV2ASP/A on Mt. Athos

I have been working on completing contacts with all of the entities in Europe for some time. I have been fortunate to earn the DARC Worked All Europe Top Plaque having successfully confirmed contacts with 72 or the 73 DX entities in Europe on a sufficient number of bands. For some time now, I have been trying to work the last entity in Europe – Mt. Athos. There is only one station in this location which is SV2ASP/A operated by Monk Apollo. Last evening while looking at the spotting cluster, I noticed that Monk Apollo was operating 40 m CW. This was the first time I was able to hear him in over a year of listening for him! He had a pretty large pileup going and was working split. After some careful listening and some tuning, I was able to make the contact for number 73 of 73.

Recording of my QSO with Monk Apollo on 40m CW

As a bonus, Roman, DL3TU recorded my QSO so I have a very nice memento from this important contact. After some looking at my log and where I currently stand on contacts to the rarer ones in Europe, I am going to set my sights on earning the DARC’s WAE Trophy Award. To date, no U.S. station has been able to complete the necessary contacts to reach this level. It requires contacting all 73 European entities on the DARC list on at least 5 different bands.

– Fred (AB1OC)

 

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)