A 40m High Performance Antenna for Field Day

40m V-Beam Wire Antenna at Field Day

40m V-Beam Wire Antenna at Field Day

The Nashua Area Radio Society has been using a 3-element wire beam antenna for Field Day for the last several years. The antenna uses three guyed 50 ft. fiberglass masts from Max-Gain Systems. The antenna uses three inverted-V style elements separated by a little over 50 ft. Since we are in the northeastern United States, we can point the antenna on a fixed, 260° heading and it covers the entire U.S. well.

40m V-Beam - EZNEC Antenna View

40m V-Beam – EZNEC Antenna View

Our 40m V-Beam antenna was initially designed in EZNEC 5.0. It was manually optimized for decent gain and front to back performance and it worked quite well. Recently, we decided to try automatic optimization software on the antenna as part of a tune-up on the design for Field Day 2018. After looking around on the Internet a bit, we discovered a software package called AutoEZ which looked ideal for my project.

AutoEZ Antenna Modeling and Optimization Software - Wires Tab

AutoEZ Antenna Modeling and Optimization Software – Wires Tab

AutoEZ is a collection of Visual Basic code and Microsoft Excel macros that act as a front-end to EZNEC 5.0 and later. AutoEZ provides a number of very useful enhancements to EZNEC including:

  • Ability to use formulas and variables to construct and modify EZNEC wire models
  • A Test Case generator and execution environment to vary model parameters and graph the results calculations run by EZNEC
  • An automatic optimizer that can adjust the parameters of an antenna model in EZNEC to optimally meet a defined set of performance goals
  • Harnesses the full power of Microsoft Excel formulas for trigonometry, logical, and other mathematical capabilities for use in EZNEC modeling
AutoEZ Antenna Model Variables

AutoEZ Antenna Model Variables

The first step in the project was to rebuild the EZNEC model that I already had for our 40m V-Beam antenna in AutoEZ. I began by defining several AutoEZ Variables and Excel Formulas in the AutoEZ Variables Tab that enabled me to easily modify the design of the antenna and to optimize it. Some of the basic variables included the target design frequency for the antenna, the height and separation of the antenna elements, the distance to the element anchor points, and the length of the element wires.

AutoEZ Antenna Model Variables (Formulae View)

AutoEZ Antenna Model Variables (Formula View)

The image above shows the model variables in “Formula View”. You can see some of the math and trig functions that were used to compute values for some of the variables. AutoEZ can only optimize variables that do not contain formulas so I was careful to ensure that the base separation between the elements and the length of the element wires were constants as these are the parameters that I wanted to optimize later.

AutoEZ Antenna Modeling and Optimization Software - Wires Tab

AutoEZ Antenna Modeling and Optimization Software – Wires Tab

Excel Trig formulas and the Variables were used on the Wires Tab to determine the coordinates of the wires in the antennas. There are a total of 7 wires in the model. Six are the two ends of the three inverted-V elements. The Seventh wire is a short 4″ section in the middle of the Driven Element to allow a current source to be inserted to drive the antenna there. I was careful to create an accurate model of the wire gauge, insulation, and loss that we are using for our V-beam

Model Variables to be Optimized

Model Variables to be Optimized

With the model built, it was back to the Variables Tab to select the parameters to be optimized. Optimization is best done as a multi-pass process and I did this in two steps. The first set of runs included optimization of both the element spacings and their lengths. This led me to conclude that the mast spacing of 27 ft (Driven to Director) and 28 ft (Driven to Reflector) were the best choices. I then set these as fixed values in the variables tab and ran the optimizer a second time with some starting element lengths to optimize the element lengths by themselves.

Optimizer Objectives

Optimizer Objectives

One must create a set of frequencies and objectives for the optimizer before running it. This is done in the AutoEZ Optimize Tab. The antenna is being used for SSB on 40m so I choose a range of frequencies that covered the SSB sub-band on 40m. Note that I weighted the center frequency heavier than the edges by including it more times in the optimizer’s list. The use of the Optimization Objectives and their associated weights and values are well covered in the AutoEZ documentation so I won’t cover them in detail here. The parameters above were chosen to create a reasonable balance between SWR values across the 40m SSB sub-band, good Front/Back and Front/Side performance from azimuth values ranging from 60º to 300º, and a reasonable amount of forward gain for a 3 element antenna of this type.

I expected that the final impedance of the antenna would be a typical value for a yagi in the 20 to 30 ohm range. Thus, I set the SWR calculations based upon a 25 ohm target impedance. More on the matching of the resulting design later…

Element Optimization Results

Element Optimization Results

It took several runs of the optimizer with different sets of Optimizer Objectives to get the final results I was looking for. The Optimizer tried 130 combinations of element lengths to arrive at the final lengths shown above. Note the improvements in SWR (1.6 -> 1.04), Forward Gain (+1 dB), Front/Back (+4.2 dB) and Front/Rear (actually Front/Side) performance that the Optimizer was able to achieve over my manual, trial and error optimization.

Post-Optimization Model Variables

Post-Optimization Model Variables

Next, I rounded the optimized element lengths and plugged them into the Variables Tab.

Post Optimization Azimuth Pattern

Post Optimization Azimuth Pattern

The image above shows the optimized Azimuth pattern for the antenna as generated by AutoEZ and EZNEC. A very clean result!

Post-Optimization Elevation Pattern

Post-Optimization Elevation Pattern

And here’s the optimized Elevation pattern near the center of the SSB sub-band. This antenna is a little low for 40m but the resulting maximum gain at a 35º angle should work well for US contacts during Field Day.

Calculated Performance for the Optimized Antenna

Calculated Performance for the Optimized Antenna

The final step in the optimization process was to calculate a full set of performance calculations for the antenna using the Calculate Tab. AutoEZ makes it very easy to generate a set of Test Cases for incremental frequencies in the SSB sub-band on 40m. Note the setting of the Elevation angle of 35º to match the maximum gain angle for the optimized antenna. Also, note the parameter settings for Ground Type and Characteristics. I set these to model the less than ideal soil conditions that we have here in New England.

Performance Plots for the Optimized Antenna

Performance Plots for the Optimized Antenna

AutoEZ provides several nice graphical capabilities via the Patterns, Triple, Smith, Custom and Currents Tabs.  I used some of them to plot the data from the performance calculations. These graphs help to visualize the results of the optimization to verify that the design objectives for the antenna have been met.

1:2 Matching Balun (25 ohm to 50 ohm)

1:2 Matching Balun (25 ohm to 50 ohm)

I am using a 1:2 matching Balun from Balun Designs at the feed point of the antenna to transform the antennas final 25 ohm feed point impedance to 50 ohm to match our coax feed line.

40m V-Beam Antenna

40m V-Beam Antenna

We are looking forward to using the optimized version of our 40m V-Beam at Field Day 2018. It took me a couple of days of time to read all of the AutoEZ documentation and learn to use the excellent tools it provides. I don’t think I will build another EZNEC antenna model without using AutoEZ. Even without the optimization features, AutoEZ makes the construction and modification of an antenna model in EZNEC far easier than it would be using EZNEC alone. I hope that you’ll give AutoEZ a try for your next antenna design project.

Fred, AB1OC

 

Upgrading our 2.0 Satellite Station for ARISS Contacts

We have been working with Hudson Memorial School near Nashua, NH to prepare for a possible ISS crew contact. The ARISS folks work with schools and their Ham Radio helpers to prepare for these contacts. ARISS provides recommendations for ground station equipment to help ensure a good experience for the students. The ground station recommendations provide a solid set of specifications to support communications with the ISS on the 2m band. The recommendations include things such as:

  • A requirement to build both a primary and a backup ground station
  • Radio and power specifications (a 200W amp is recommended)
  • Antenna specifications including recommendations to provide for switchable LHCP and RHCP
  • Computer controlled azimuth/elevation positioning of antennas to track the ISS
  • Use of a receive preamplifier at the antenna
Portable Satellite Station 3.0 Antenna System

Portable Satellite Station 3.0 Antenna System

We have recently completed construction and testing of our Portable Satellite Station 3.0 which was built specifically to meet the primary station requirements for our ISS contact.

Our plan is to add some upgrades to our Portable Satellite Station 2.0 to create a Portable 2.1 Station which meets the backup station requirements. These upgrades will include:

All of the equipment needed to upgrade our 2.0 Portable Station to 2.1 is either here or will arrive shortly. Here’s some more information on the planned equipment.

Icom IC-910H Transceiver

Icom IC-910H Transceiver

The Icom IC-910H was Icom’s flagship Transceiver for Satellite work before the IC-9100 was released. It’s a very nice satellite radio! Dave, K1DLM graciously lent us his IC-910H for use in our backup station.

Green Heron RT-21 AZ/EL Rotator Controller

Green Heron RT-21 AZ/EL Rotator Controller

We already have a Green Heron Az/El Rotator controller setup for the Yaesu Rotator system on the 2.0 Antenna Tower and we will be reusing it for the 2.1 station.

GHTracker Running On A Raspberry Pi 3

GHTracker Running On A Raspberry Pi 3

We are also planning to build a second Raspberry Pi Rotator Interface for it.

M2 Antenna Systems PS2MCP8A Polarity Switch

M2 Antenna Systems PS-2MCP8A Polarity Switch

M2 Antenna Systems recently added a new 2M polarity switch, the PS-2MCP8A, designed for use with the 2M antenna in their LEO Pack which we are using in our 2.0 Antenna System. We will be installing this relay as well as a PS-70CM polarity switch relay for the LEO pack’s 70cm antenna as part of the 2.1 Antena System upgrade.

DXEngineering EC-4 Control Box

DXEngineering EC-4 Control Box

We will add another DXEngineering EC-4 BCD Control Console to control the polarity switching relays on the upgraded antennas.

m RM ITALY LA-250V Amplifier

RM ITALY LA-250V Amplifier

The final new component in our 2.0 to 2.1 upgrade is the addition of a 200W RM ITALY LA 250 power amplifier. We have opted for the version of this amplifier with the cooling fans. The unit is very well made and we are anxious to see how it performs on the air.

Some of our readers might be wondering what we are planning to do with all of Portable Satellite Ground Station equipment in the long run? We plan on keeping the 1.0 Portable Station for grid square activations and demonstrations. Its simple, battery-powered approach and small antenna make it ideal for this sort of work.

The upgraded 2.0 Portable Station with its enhanced polarity switching will become our transportable station for License Class and Field Day use. It will be converted at the end of 2018 to use our Icom IC-9100 Transceiver that is currently part of the 3.0 station.

We plan to use the Portable 3.0 Station through the year (2018) to support the planned ARISS contact, Field Day, and some demonstrations at local Ham Fests and schools. Once these are complete, we plan to permanently install it here at our QTH and it will become our main satellite ground station at our home QTH.

You can view all of the articles about our Portable Satellite Stations via the links below.

We will begin construction of the 2.1 upgraded station once a few remaining components arrive here. We plan to share some more about the construction and initial testing of our 2.1 Portable Station here.

Fred, AB1OC

A Portable Satellite Station Part 6 – 3.0 Station Initial Contacts

Tech Class First 3.0 Portable Station Test

Tech Class First 3.0 Portable Station Test

With the construction of our Portable Satellite Station 3.0 complete, we’ve been looking forward to an opportunity to test the new setup. We chose the Nashua Area Radio Society’s recent Technician License Class as a good time to both test the new stations and to acquaint our Tech Class grads with one of the many things that they can do with their new licenses – amateur satellite operations.

Tech Class 3.0 Portable Satellite Antenna Test

Tech Class 3.0 Portable Satellite Antenna Test

The first transport of the new 3.0 station antenna system turned out to be simple. The booms and counterweights of the new antenna system are easily separated via the removal of a few bolts located at the cross-boom. This allowed the antennas feed-points, rotator loops and polarity switching connections to be removed and transported as complete assemblies. The separation of the longer-boom antennas into two sections also made transporting the antennas easier and made the antenna elements less prone to bending in transport. Setup and cabling of the new 3.0 antenna system as the class site was quick and simple.

The opportunities to make contacts during our Tech Class were limited but the new system performed well with one exception. We saw a higher than expected SWR readings on the 70cm yagi during transmit. We immediately suspected problems with one of the N connectors that were installed during the construction of the new system (component testing during assembly showed the SWR readings on the 70cm side of the system to be in spec.).

Portable Satellite Station 3.0 Antenna System

Portable Satellite Station 3.0 Antenna System

After the class, we set up the 3.0 system again at our QTH. Transport and re-assembly of the new system are somewhat easier and faster than our 2.0 portable station antenna setup is.

Satellite Antenna System 3.0 Connections

Satellite Antenna System 3.0 Connections

The 3.0 antenna system uses a similar connector bulkhead approach that we used previously. The rotator controls are handled via a single, 8-conductor cable and we have a new connection for the polarity switching controls on the 3.0 system yagis.

Rotator Loop Coax Retention System

Rotator Loop Coax Retention System

We have had some problems with the connections between the preamplifiers mounted at the antennas and the rotator loops which connect the antennas to them. This problem caused several failures in the associated N-connectors on the 2.0 portable antenna system so we fabricated a simple arrangement to prevent the rotation of the antennas from turning the coax inside the N-connectors and causing these failures.

70cm Yagi SWR in the Satellite Sub-Band

70cm Antenna and Feedline SWR in the Satellite Sub-Band

Some isolation tests were performed on each cabling element of the 70cm side of the 3.0 antenna system and this resulted in the location of an improperly installed N-connector. The faulty connector was easily replaced and this corrected the SWR readings on the 70cm side of the antenna system. The image above shows the SWR readings for the 70cm antenna after the faulty connector was replaced. We checked the SWR performance with the 70cm yagi set for both Left-Hand and Right-Hand Circular Polarization and we saw good results in both configurations.

2m Yagi SWR in the Satellite Sub-Band

2m Antenna and Feedline SWR in the Satellite Sub-Band

We also re-checked the SWR performance of the 2m side of the antenna system with the 2m yagi in both polarity settings and it looked good as well.

Portable Satellite Antenna 3.0 Az-El Rotator

Portable Satellite Antenna 3.0 Az-El Rotator

The 3.0 antenna system uses an Alfa-Spid rotator. The Alfa-Spid can handle the additional weight of the larger yagis and has a more precise pointing ability (1° accuracy) which is helpful given the tighter patterns of the larger, 3.0 yagis.

70cm Yagi Switchable Polarity Feedpoint

70cm Yagi Switchable Polarity Feedpoint

The new yagis in the 3.0 antenna system have feed point arrangements which allow the polarity of the yagis to be switched between Left-Hand Circular Polarity (LHCP) and Right-Hand Circular Polarity (RHCP). These antennas used a relay arrangement at the feed-points that flip the polarity of one plane of the yagis by 180° which in turn changes the polarity of the antennas between LHCP and RHCP.

Portable Satellite Station 3.0 Radio and Controls

Portable Satellite Station 3.0 Radio and Controls

With the SWR problem corrected, we set up the 3.0 station radio and controls. The 3.0 station adds our homebuilt PTT Router and the control box from DXengineering which controls polarity switching. Also, the Green Heron rotator control box has been configured to control the new Alfa-Spid rotator.

POrtable Satellite Station 3.0 Computer Control via MacDoppler

Portable Satellite Station 3.0 Computer Control via MacDoppler

We are continuing to use the excellent MacDoppler software to control the 3.0 station. MacDoppler provides tracking controls for the antennas and doppler correction for the Icom-9100 transceivers uplink and downlink VFOs.

Satellite 3.0 Station Control Details

Satellite 3.0 Station Control Details

The image above shows a closer view of the 3.0 station controls. The box in the middle-left with four LEDs and the knob is used to select one of four polarity configurations for the 2m and 70cm yagis – RHCP/RHCP, LHCP/RHCP, RHCP/LHCP, or LHCP/LHCP. Just to the right in the middle stack is our homebrewed PTT Router which expands and improves the PTT sequencing performance of the station.

So how does the new 3.0 station perform? The new antennas have a tighter pattern requiring careful pointing calibration of the rotators during setup. This is easy to do with the Alfa-Spid rotator. The new antennas have noticeable more gain as compared to the LEO pack used on the 2.0 station. We are also surprised to see how much difference the polarity switching capability makes in certain situations – sometimes as much as two S units (12 dB) in certain situations. The combination of the new antennas and selection of the best polarity combination allows solid operation on many satellites passes with as little as 2 watts of uplink power. We have made a little over 50 QSOs on the new 3.0 station so far and it works great! For more information on the Portable 3.0 Station as well as the 2.0 and 1.0 stations that we’ve built – see the links below:

Fred, AB1OC

 

ISS Crew Contact

We have been working with Hudson Memorial School to help them secure and prepare for an ISS Crew Contact. We are hoping to support their ISS Crew Contact using an upgraded version of our Portable Satellite Ground Station. A school in Raleigh, North Carolina had their ISS Crew Contact today and I decided to record the downlink from the ISS to test our backup Portable 2.0 ISS/Satellite Ground Station.

The video above is a capture of the school’s contact. It was very easy to receive the ISS downlink on our portable backup ground station. I heard the downlink a few seconds before the ISS came up on the horizon and the audio was solid for the duration of the contact. We can only hear the astronaut’s side of the contact as we cannot receive the school’s uplink from Raleigh, NC. The ISS pass began here in New Hampshire part way through the school’s session so we did not hear the first few questions.

Update on Portable ISS/Sat Station 3.0

Portable ISS/Sat Station 3.0 Antenna System

Portable ISS/Sat Station 3.0 Antenna System

Work on our upgraded primary Portable 3.0 Station which includes a larger antenna system using switchable circular polarity is progressing well. The portable tower, upgraded rotator system, and the new, larger 2m and 70cm circularly polarized antennas are complete.  We are just waiting for a few additional components to arrive here and the upgraded portable ground station should be ready for its first test at our Technician License Class later this month.

More on Today’s ISS Crew Contact

You can see a live stream of the ISS Contact from the school above. There is a great deal of planning which goes into an ISS Crew Contact such as this. We are working closely with Hudson Memorial School on their project and their school is also beginning a High-Altitude Balloon Project with us in a few weeks.

The ISS Crew Contact today was exciting to listen too and we are looking forward to being able to share this experience with Hudson Memorial School in the near future.

Fred, AB1OC

An 80m Broadband Matching System

Our Tower with 75m Loop

Our Tower with 75m Loop

We installed a 75m loop for SSB operation on our tower when we built it. The loop is full size and is diamond shaped so that our lower SteppIR DB36 yagi can rotate inside of it. The loop is fed at the bottom corner about 20 ft up from the ground. It works great for SSB operation on 75m but we have often wished we could use it across the entire 80m band. This goal led to a project to create a matching system for the antenna. The idea was to use a set of loading coils in series at the feed point create a good match in all segments of the 80m band.

EZ-NEC Model for 75m Loop

EZ-NEC Model for 75m Loop

The first step in the design of our 80m matching system was to build a model of our current loop using EZ-NEC. The model was then used to determine the correct values of a set of series loading inductors to match different segments of the 80m band.

Matching System Design Analysis

Matching System Design Analysis

We also considered how likely different segments of the 80m band were to be used by profiling historical spotting data from DXSummit. All of this analysis led to the creation of a final design which is captured in the spreadsheet shown above. The final design requires our current 75m loop to be shortened a bit to work well at the very top of the 80m band.

Modeled Loading Coil Inductance Values

Modeled Loading Coil Inductance Values

A set of 5 different inductor pairs can be used in series with the loop’s feed point to create a good match across the entire 80m band. The modeled values for the series matching inductors is shown above.

Matching System Modeled SWR

Matching System Modeled SWR

Our microHAM control system can easily implement the switching of the various inductance values based upon the frequency that a radio using the antenna is tuned to. Result modeled SWR for the final 80m loop and match combination is shown above. The design should achieve an SWR < 1.5:1 across the entire 80m band except for the very top where the SWR remains < 2:1. Also, the design optimizes the system’s SWR in the important CW DX, SSB DX, and Digital windows on the 80m band.

Layout of Components in Enclosure

Layout of Components in Enclosure

With the design completed, we choose an enclosure and all of the components. Here are the details of what we used:

The first step in the construction was to layout all of the components in the enclosure. Attention was paid to keeping the two series inductors at right angles to avoid coupling and to keep RF connections as short as possible. The relays were arranged to keep the leads connecting to the coils of roughly equal length. Finally, the control circuitry was kept as far removed from the RF leads as possible.

Enclosure Mounting Ears and Clamps

Enclosure Mounting Ears and Clamps

The matching system attaches to a tower leg via saddle clamps. We fabricated a set of mounting ears and spacer blocks to position the enclosure far enough away from the tower so that the antenna connections do not interact with the tower.

80m Matching System Construction

80m Matching System Construction

A summary of the completed matching system construction is shown above.The design uses a set of four double-pole double-throw relays to switch in different coil taps which selects the loading inductance provided by the matching system.

We did a set of calculations and found that our relays would be subjected to a worst case peak-peak voltage of about 2.1 KVp-p at the coil tap points.

The relays are arranged such that two sets of contacts have to be traversed to select any given coil tap. The relays we are using have a third pole which we are not using. We disassembled each relay and removed the internal contact wiring for the center pole which improves both the coil to contact voltage rating and the isolation values of the relays.

These steps combine to improve the voltage rating of the system. This is an important design element given that the match will operate at legal limit power.

Completed RF Deck

Completed RF Deck

The completed RF deck and control circuitry is shown above. The enclosure we choose came with a removable plastic plate that made mounting and wiring all of the components simple.

Loading Coil Mounting and Taps

Loading Coil Mounting and Taps

The loading inductors are mounted using nylon hardware with the ends connected to the two antenna terminals on the sides of the enclosure. The coils use movable tap clips to allow us to fine-tune the match once the system is installed with the antenna on our tower. The initial clip locations are set to create the inductance values modeled during the design phase.

Relay Control Circuit Connections

Relay Control Circuit Connections

The relay control leads use twisted pair wiring to minimize RF pickup. The control leads are routed away from the RF connections to minimize potential RF coupling.

Relay Control Circuit Details

Relay Control Circuit Details

The control circuits for each relay use a combination of a Diode, a Varistor (MOV) and a filter capacitor in parallel to avoid relay coil switching interference and to suppress control line noise.

1.5 to 1 Matching Balun

1.5 to 1 Matching Balun

The matching system is designed to operate at 75-ohms which is pretty close to the resonant impedance of our 75m loop. The current antenna uses a 1.5:1 Balun to match the loop to our 50-ohm coax feedline. We disassembled an identical matching balun (actually a 75-ohm balun plus a 1.5:1 unun) and used it without its enclosure to create a final 50-ohm match.

MicroHAM Setup to Control 80m Matching System

MicroHAM Setup to Control 80m Matching System

The final step in the construction of our matching system was to program our microHAM antenna switching system to properly configure the relays in our matching system. This was quite simple to do using microHAM’s frequency dependent antenna control capabilities. The microHAM system automatically operates the appropriate relays to create the best possible match as the radio which is using the matching system is tuned across the 80m band.

Unfortunately, we are in the middle of winter here in New England so I will have to wait for warmer weather to install our new matching system on the tower and make the final adjustments. I am planning another article here when the final integration steps are done to cover the performance of the completed project.

Fred, AB1OC

A Portable Satellite Station Part 5 – Plans for Our 3.0 Station

Satellite Grids Worked

Satellite Grids Worked

We’ve made about 250 contacts with our Portable Satellite Station 2.0 and we have worked 106 grids which should be enough to earn a Satellite VUCC. The picture above shows the grids that we’ve worked via Satellites. We’ve learned a lot about satellite operation and had a great deal of fun in the process!

Portable Satellite Station 2.0 Goals

Portable Satellite Station 2.0 Goals

We’ve met all of our original goals for our 2.0 Station and we’ve used it portable at License Classes, Field Day, and other Amateur Radio Demonstrations. We’ve also shared presentations about our 2.0 Station with Amateur Radio Groups here in the New England area. The question that we get most often about the 2.0 Station is “What are your plans for the Portable Satellite Station 3.0”?

Portable Satellite Station 3.0 Goals

Portable Satellite Station 3.0 Goals

Well, here is the plan. We are working with a local group to secure and host an ISS Crew contact. The ARISS folks have published ground station requirements for these contacts. Here are the primary station requirements:

  • Transceiver with 50–100 W output, 1 kHz tuning steps, and 21 memories capable of storing split frequencies
  • Low-loss coax (such as 9913 or LMR-400)
  • Mast-mounted receive pre-amplifier
  • 14-element yagi antenna with switched circular polarity
  • Antenna rotators for azimuth (0–360°) and elevation (0–180°), with an interface for computer control
  • Computer running tracking software for antenna control (including flip mode operation)

Fortunately, our 2.0 Station meets or exceeds almost all of the primary station requirements with the exception of the antennas. The required antenna upgrades will shape the plans for our Portable Satellite Station 3.0.

M2 Antenna Systems 2MCP14

M2 Antenna Systems 2MCP14

ISS Crew Contacts are conducted using 2m Simplex radios on the ISS. We choose the 14-element circularly polarized 2MCP14 yagi from M2 Antenna Systems to meet the ARISS requirements for 2m. Here are the specifications for this antenna:

2MCP14 Antenna Specifications

2MCP14 Antenna Specifications

The 2MCP14 antenna offers a good balance between gain (12.34 dBi) and boom length (10′-6″) and is near the size limit that is practical for use in our Portable Station. This antenna provides an additional 3.14 dBi of gain compared to the M2 Antenna Systems 2MCP8A yagi which we are currently using in the 2.0 Station.

M2 Antenna Systems 436CP30

M2 Antenna Systems 436CP30

While not required for an ARISS Crew Contact, we are also going to upgrade the 70cm yagi to a 30-element circularly polarized M2 Antenna Systems 436CP30 yagi. Here are the specifications for this antenna:

436CP30 Antenna Specifications

436CP30 Antenna Specifications

This antenna is a good match for the upgraded 2m yagi. The 436CP30 has a boom length of 9′-9″ and a gain of 15.50 dBi. This antenna will provide an additional 2.2 dBi of gain compared to the M2 Antenna Systems 436CP16 yagi which we are currently using in the 2.0 Station.

Satellite Antennas Setup Portable

Satellite Antennas Setup Portable

The new antennas will require some modifications to our portable antenna system arrangement. They will need to be mounted on a cross-boom near their centers. As a result, a non-conductive fiberglass cross boom will be required to avoid problems with pattern distortion.

FGCB60 Non-Conductive Cross Boom

FGCB60 Non-Conductive Cross Boom

We will be using an M2 Antenna Systems FGCB60 Cross Boom which has removable, non-conductive end sections made from fiberglass material. The removable ends will make it easier to transport the antenna system. We will also need to make a new mast which is 24″ longer than our current one in the 2.0 Station to create the needed ground clearance for the longer antennas.

Alfa Spid Az-El Rotator

Alfa Spid Az-El Rotator

We are also planning to use a larger Alfa Spid Az-El Rotator. This unit will handle the extra weight of the longer yagi antennas and cross boom assembly and is more precise than the Yaesu unit used on the 2.0 station.

PS-2M and PS-70CM Polarity Switches

PS-2M and PS-70CM Polarity Switches

The last piece of the 3.0 Station Antenna upgrade is to add switchable left-hand and right-hand circular polarity. This will be accomplished via M2 Antenna Systems PS-2M and PS-70CM switchable polarity feed point upgrades for the 3.0 yagis.

DXEngineering EC-4 Control Box

DXEngineering EC-4 Control Box

We have a DXEngineering EC-4 Control Box from a previous project and we can use it to control the relays in the Polarity Switches which will be part of the 3.0 Station antennas. The box will allow us to select any combination of left and right-hand circular polarization on the 3.0 Station uplink and downlink antennas.

We should have all of the parts here for the 3.0 upgrade by the end of the year. We’ll post more as the project proceeds. Other articles in the Portable Satellite Station series include:

You may also be interested in the satellite station at our home QTH. You can read more about that here.

Fred, AB1OC

Portable Satellite Station Design and Operation

Building and Operating a Portable Satellite Station Presentation

Portable Satellite Station Design and Operation Presentation

Anita and I attended the New England Regional Hamvention this past weekend. We gave a presentation on Portable Satellite Station Design & Operation there. You can view a copy of our presentation here.

Satellite Station Portable - Radio and Supporting Equipment

Portable Satellite Station 2.0 at a Recent License Training Class

The Videos from our presentation follow below –



We did two additional talks about the Nashua Area Radio Club’s activities including one on our High-Altitude Balloon Project. You can view those presentations here.

Also, we are planning to have our 2.0 Portable Satellite Station setup at the Nashua Area Radio Club’s upcoming Technician License Class on Sept. 30 – Oct. 1. If you are in the area and would like to see the station in operation, please contact us at activities@n1fd.org to arrange for a visit. If you’d like to register for one of our license classes, you can do that here.

Fred, AB1OC

Portable 6M Station for SOTA and Contesting

Fred, AB1OC and Curtis, N1CMD Operating

Fred, AB1OC and Curtis, N1CMD Operating

I got really exited, when Jamey, KC1ENX set our Club’s first Summits On The Air (SOTA)/Parks On The Air (POTA) activation for the same day as the June VHF Contest! Jamey choose Pack Monadnock in Miller State Park here in New Hampshire as the site for our activation. With Jamey’s help, we put together a portable 6M station in preparation for the activation.

Solar Panels

Solar Panels

The idea was to use an IC-7300 to create a 100W station and use a Solar/Battery combination to power the setup. Solar/Battery made us “legal” as a SOTA activation. We combined two 90W solar panels which I had with a MPPT solar charing system and two LiPo batteries to create the power system for the activation.

6M Antenna Going Up

6M Antenna Going Up

The antenna system was built around a M2 Antenna Systems 6M3 Yagi and a 18 ft. push up mast from Max-gain systems.

Portable 6M Antenna

Portable 6M Antenna

All of this gear was carried to the site and setup in about an hour. A 25 ft. section of LMR-400UF coax completed the station. The mast was guy’ed with rings which allowed us to turn the mast/antenna combination to point the Yagi in any direction.

Anita, AB1QB and Curtis, N1CMD Operating in the June VHF Contest

Anita, AB1QB and Curtis, N1CMD Operating in the June VHF Contest

Between the SOTA/POTA activation and the June VHF contest, we made a little over 130 contacts on 6m. We did not have any real Es openings so most of our contacts were regional. Having the elevation provided by being on Pack Monadnock made us quite loud for the stations that could hear us. Several of our club members got on 6M and joined the fun. We did have a brief Es opening and managed to work a station in Alabama and one in Florida.

Mike, AB1YK Portable 6M

Mike, AB1YK Portable 6M

Mike, AB1YK has a much more portable 6M setup and used lower power to have some fun on 6M as well.

Al, KC1FOZ and Tom, KC1GGP Operating Portable

Al, KC1FOZ and Tom, KC1GGP Operating Portable

Al, KC1FOZ and Tom, KC1GGP put together a nice station and operated using battery power. Several other club members came out with portable station or to watch and have fun as well.

Our first SOTA/POTA activation was a lot of fun and Anita and I are looking forward to the next one!

Fred, AB1OC

GoKit for Field Day and EMCOMM

Completed VHF/UHF GoKit

Completed VHF/UHF GoKit

We’ve been thinking about building a portable GoKit for VHF/UHF EMCOMM and Field Day Applications for a while now. The following is a list of our requirements for a GoKit –

  • 2m and 70cm operation with FM simplex and repeaters
  • APRS capability and tactical display for portable coordination
  • Digital messaging capability
  • Weather band monitoring capability
  • AC Power with flexible battery backup options

A plan to build our GoKit came together during our trip to the Dayton Hamvention this year.

Kenwood TM-D710GA At Dayton

Kenwood TM-D710GA At Dayton

The heart of any GoKit is the Transceiver. We’ve been using Kenwood equipment for our APRS iGate for some time now and we have had good results with it. Kenwood’s latest 50W transceiver with APRS is the TM-D710GA. This unit provides full support for APRS tactical applications and now includes a built-in GPS receiver making it ideal for our GoKit application.

AvMap GeoSat 6 APRS Tactical Display

AvMap GeoSat 6 APRS Tactical Display

We have been using the Kenwood TM-D710 along with an AvMap GeoSat APRS display in our APRS iGate setup and the combination works very well. The AvMap display lets one see the location of portable and mobile APRS stations on a map display. This arrangement is perfect for coordinating activities in an EMCOMM situation. The AvMap GeoSat 6 APRS display is no longer in production but I was able to locate a nearly new unit on eBay.

3 - iPortable Enclosure

We had a chance to look at the iPortable enclosure at Dayton and decided that their Pro 2 4U deep unit would be a good choice for our GoKit application. The iPortable enclosures are based on a portable rack mount case and include a DC power system, speaker and headphone hookups, a light, and provisions for a cooling fan.

Radio Shelf

Radio Shelf

With all the components in hand, we began the construction of our GoKit. Reliability is important in any portable system like this so we put some time into securely mounting all of the equipment and neatly arranging the cabling. First came the shelf which holds the Kenwood transceiver and a SignaLink USB sound card. A combination of drilling the shelf to secure gear with large cable ties and #8 stainless hardware was used here.

Coax Connector Cables

Coax Connector Cables

Our iPortable case was equipped with both SO-239 and N-connectors on the front panel to allow for antennas and feed lines equipped for either connector type. To make the change over between the connector types easy, we installed separate PL-259 jumper cables for each connector. One simply connects the appropriate jumper to the radio.

Display and Power Shelf

Display and Power Shelf

The power and AvMap display shelf was next. The AvMap display mount was dissembled and modified to accept a custom mounting bracket.

PWRgate Battery Interface and Charger

PWRgate Battery Interface and Charger

The iPortable enclosure was drilled to mount a West Mountain Radio PWRgate to handle backup battery charing and management. The PWRgate supports instantaneous switching between an AC power supply and a backup battery and can accommodate a wide range of battery types and sizes.

Backup Battery

Backup Battery

The PWRgate was configured to properly charge our 18AH AGM backup battery. Note the use of a fuse in series with the battery for safety reasons. We used a Powerwerx SPS-30DM adjustable power supply set to 14.5Vdc to operate our GoKit and to provide proper charging voltage for our AGM battery.

Diamond X-30 Antenna and Mast

Diamond X-30 Antenna and Mast

The last piece of the setup was the antenna. We wanted something that was portable, easy to set up and would provide good performance. We choose a Diamond X-30A 2m/70cm ground plane antenna and mounted it on an 12′ fiberglass push up mast. The feed line is made from 25′ of LMR-400UF coax. Several bungee cords are used to attach the mast to a fence post or other vertical structure.

10 - GoKit In Use

The picture above shows the completed GoKit in operation. We typically set one side of the Kenwood TM-D710GA to operate as an APRS transceiver and Digipeater and the other side to operate on a local repeater or simplex FM. The SignaLink sound card is used with a laptop computer running Fldigi and NBEMS for messaging applications. The iPortable case has a 13.8V lighter socket which connects to a power brick to power our laptop PC.

GoKit Packaged for Transport

GoKit Packaged for Transport

The GoKit is quite portable when closed. All of the equipment and cable connections are enclosed and protected by the case’s removable end caps. We’ve tested our GoKit during our club’s weekly repeater net and it worked great. The first real use of our new GoKit will be at Field Day this year. It will be located in our public information tent and will be used as a “talk-in” system.

Fred, AB1OC

 

A Portable Satellite Station Part 4 – 2.0 Station First Contacts!

Station Packed and Ready for Transport

Station Packed and Ready for Transport

With our new 2.0 Satellite station built, tested, and packed; we were ready to try it in a portable environment. Fortunately, the Nashua Area Radio Club had a Technician License class coming up and we thought that the new station test would be a great way for our students to learn about Amateur Radio Satellites.

Satellite Status from AMSAT Website

Satellite Status from AMSAT Website

Final preparations included checking the operational status of potential satellites on the AMSAT website. The page shown above is like a spotting cluster for LEO Satellites – it shows satellite activity as reported by HAM satellite operators. Using this information, we configured MacDoppler to track the active satellites.

Satellite Pass Predictions

Satellite Pass Predictions

Next, we used MacDoppler to generate pass predicts for the weekend of our Technical Class. We assembled this data for all of the potential satellites and color-coded the available passes to identify those which had the best chance of producing contacts.

With this done, we loaded our portable tower, antennas, and all of the rest of the gear into our pickup truck and transported it to the class site.

Sateliite Antennas Setup Portable

Satellite Antennas Setup Portable

The first step at the class site was to unload all of our gear and move the portable tower to a suitable location. We used a compass to orient the tower to true north and leveled it. We used the weight bags that we made up to anchor the tower securely and then installed the antennas, rotator loops, and control cables. The antenna system worked out very well in the portable environment and was easy to set up.

Satellite Antenna Details

Satellite Antenna Details

Here’s a closer to look at the LMR-400 UF coax cables which connect the antennas to the rest of the system. The loops just behind the antennas are necessary to keep the coax from affecting the pattern of the antennas. The coax cables shown were made long enough to allow the antennas to be rotated through their full travel in the azimuth and elevation directions without binding.

Satellite Station Portable - Radio and Supporting Equipment

Satellite Station Portable – Radio and Supporting Equipment

The final step in the portable setup was to put the IC-9100 Transceiver and Supporting Equipment together in the building and check everything out. As soon as we got everything hooked up and working, we heard an ON4 station through FO-29 which was near the end of a low angle pass. A very good sign!

We took some time to fine-tune the calibration of our rotators and to check the operation of the computer controls – everything checked out fine. The video above shows MacDoppler controlling the Azimuth/Elevation rotator and the IC-9100 Transceiver during the testing.

First Contact using New 2.0 Station (AO-85)

First Contact using New 2.0 Station (via AO-85)

With all the setup done, it was time to try to make our first contact. Fortunately, we did not have long to wait. We caught a medium angle pass of AO-85, a U/V Mode FM Easy Sat. With MacDoppler setup and tacking, we immediately heard contacts being made through AO-85. I gave a whistle and adjusted my uplink VFO until I heard my signal coming back through AO-85. I gave a quick CQ call and immediately got a response from Jonathan, NS4L in Virginia, USA! It took on a few seconds to exchange call signs and grid squares and our first contract with our new station was in the log.

Explaining Satellite System to License Class

Explaining Satellite System to License Class

Our Technician License Class students were very interested in the station. We spent some time explaining the setup and demonstrating how it worked. We made more contacts between our class sessions using AO-85 and FO-29 (a V/U Mode Linear Transponder Satellite). Our most interesting contact was with Burt, FG8OJ in Guadeloupe through FO-29. It was great to work DX using the new station during the first time we used it.

We learned several things during our first use of the new station. First, while the 35 ft. maximum separation allowed between the antenna system and the rest of the station is adequate in many applications, the antenna system’s close proximity to the building we were in blocked passes to the west of us with this separation. We have subsequently made up an additional set of feed lines using a pair of 100 ft. long 7/8″ hardline coax cables to allow for a greater separation in portable deployments such as this one.

We were glad that we had the Heil Pro 7 Headset with us and we used it for most of our contacts. The separate speaker allowed our students to hear the contacts well and the boom microphone on the Pro 7 Headset eliminated feedback due to our own voice coming back through the satellites. We improvised a mono to stereo converter cable to connect the Heil Pro 7 Headset to one of the two speaker outputs on the IC-9100 Transceiver. This allowed the radio to drive the separate speaker and the headphones at the same time.

We were glad to have the low-noise preamps available. These were especially useful during low-angle satellite passes and the sequencing setup that we built worked well.

All in all, the first test of our new 2.0 Portable Satellite station was a success. Our license classes students enjoyed learning about Amateur Satellites and had fun along with us making contacts through a few of them. Our next goal will be to get packet modes and APRS working with our setup. We plan to do another article in this series when this part of our project is completed. Other articles in this series include:

We are planning to add larger antennas and switchable polarity to our portable satellite station in the near future. This will enable us to make contacts with Satellites and the ISS in more difficult conditions.

You may also be interested in the satellite station at our home QTH. You can read more about that here.

Fred, AB1OC