I had a fun day on the radio yesterday. It started with the Matrix QO-100 Satellite Impromptu Net at 16:00 BST on 10489.873Mhz. A net that started off as an impromptu event that over the last couple of years has become a weekly staple. Hardly impromptu at all but, we liked the name and so stuck with it.
During the Impromptu net I noticed that my 2m radio was burbling away in the background and that a lot of European repeaters were coming through so, as soon as the net had finished I quickly switched over to my trusty Wouxun KG-UV980PL and started tuning around the 2m band.
2m was alive with repeaters from France, Belgium, The Netherlands and the UK, often beating against each other on the same frequency.
Being near the East Coast and closer to Belgium than I am to many parts of the UK I jumped onto the ON0WV repeater in Bruges. Being S9+ with me I called a few times but, no one came back to me so, I moved on.
Tuning across my Norwich Repeater memory slot I heard two French stations chatting, it was obvious they weren’t on GB3NB as the bell between overs was not the normal chime.
I quickly opened RepeaterBook on my iPhone and searched for repeaters on the same frequency, there are many!
Eventually I worked out that it was ON0HT so I quickly set about loading the repeater settings into the next available radio memory channel. I loaded a few others from The Netherlands at the same time as I was hearing more than normal from that part of the world.
2 French Operators on the ON0HT repeater in Belgium close to the French border.
Having the correct settings in place for the repeater I was now able to call in and have chat with the two stations.
Jean-Claude F5JOX and Didier F6DKO were surprised to hear an English station call in but, were most welcoming. We had a chat for a few minutes exchanging details and commenting on the great conditions. Sadly the conversation was eventually brought to an end as there were so many repeaters on the same frequency it became impossible for me to hear them clearly so, I gave them 73 and went tuning around.
The 2m band was absolutely full of UK and EU repeaters with many beating against each other on the same frequency. Wouldn’t it be nice if there was more of a split between the UK repeater frequencies and the EU allocation. Would certainly make it easier to use the EU repeaters in lift conditions.
Later in the evening Roger G8VLR, Steve M0XVT and I were having one of our Impromptu Nets on the 60m band. Often there are others from the Matrix that join in too but, on this occasion there were just the 3 of us.
I’m acutely aware that we often have listeners to our on air chats as I quite often get emails from SWL’s and licenced HAMs commenting on how much they enjoy our conversations. Yesterday evening was no exception as it turns out that we were once again attracting listeners albeit, unbeknown to us at the time.
Later in the evening Alan, G1SQB sent me a message via the Matrix with a YouTube link to a recording of us on the 60m band from that very same evening made by @KevinOReillyswl.
Yes, that’s yours truly waffling on about satellites as normal.
Kevin O’Reilly is clearly a very active SWL as he has many interesting videos on his Youtube Channel that are worth a look.
I must confess that I’ve never heard of the MLITE-880 receiver before but, after running a search I found it to be quite a popular radio in the SWL community.
There’s a very good review on swling.com that’s worth a read.
The short video above shows it to be a surprisingly good shortwave receiver in a very compact, portable package that’s ideal for listening whilst out and about on camping trips or other outdoor activities.
A big thanks to Kevin O’Reilly for posting the video and letting us see how we sound on the other end.
I’ve not been on the radio much over the last few weeks as I’ve had my head down other radio related rabbit holes.
One of the rabbit holes is a Node-Red project to make my online logs a little more interactive. For sometime now my logs have been displayed on my website as nicely formatted, searchable HTML pages however, they don’t really allow the viewer (myself included) to see the global coverage of all the contacts so, I decided to write a Node-Red flow that would do just that.
M0AWS Interactive Log Flow
The flow itself isn’t too complicated and basically consists of reading in the individual ADIF formatted log files, processing the data and then sending the data in the correct format to the map node for display.
I’ve had to write a few functions to handle the processing of the ADIF formatted data but, these aren’t particularly complex and are fairly easy to understand even if like me, you’re not a Javascript programmer.
The flow is working perfectly however, I’m in the process of reworking the format generic payload function to reduce the amount of code and make it more efficient.
M0AWS SSB / CW / FreeDV Interactive Log World Map
M0AWS Interactive Log Map Layers Menu
The flow generates two maps, one for voice / CW /Satellite contacts and the other for WSJT-X FT4/8 contacts. Every pin on the map is colour coded by band with satellite contacts being denoted by a satellite icon.
Each pin / icon on the map is clickable and reveals the data of the QSO being displayed.
In the top right-hand corner of the map there is a drop down layermenu that allows the viewer to filter by band thus reducing the number of icons on the screen at any one time.
Seeing the data presented on a map really brings my logs alive. An example of this is that I had no idea I’d worked so many stations in India on the QO-100 Satellite.
The small icons in the pins show a microphone for SSB/FM/FreeDV contacts and a downwards pointing triangle in a box for CW contacts. Sadly I couldn’t find a Morse key icon in the collection available.
M0AWS filtered view of QO-100 Satellite contacts
I only use FT4/8 for testing new antenna designs however, it’s interesting to see the global coverage accomplished with this weak signal mode.
M0AWS WSJT-X FT4/8 Interactive Log World Map
Once I’ve finished rewriting the format generic payload function I will make the flow available for download here so that others can also create an interactive view of their radio logs.
If you want to have a look at the maps and try them out for yourself, they are available under the Logs menu above.
This Node-Red instance is running in a virtual machine (VM) on a 16GB RAM RaspberryPi 5 that is also running a number of other VMs at the same time so, it’s safe to say it’s not heavy on CPU and will run on the older Pi4 as well.
Back in January 2025 I wrote an article about a little RadioBerry Project I’d started that was based around a very old Philips 170A-15 receiver from 1946.
The idea of the project was to build a nice shortwave receiver for the radio shack based around the RadioBerry HAT on a RaspberryPi 4 housed in a vintage receiver cabinet.
The project has taken longer than I imagined due to getting side-tracked by other projects that I already had ongoing.
With the original internals removed there’s plenty of room inside for the RadioBerry, RaspberryPi 4 and the small 15w audio amplifier. The audio is delivered via a pair of Celestion speakers that I had that were originally part of an old surround sound TV system.
Power distribution is achieved very simply using a multi-plug adapter that also has USB A connections in it. The whole thing is then powered via one 240v mains cable.
The screen fits over the original opening for the glass tuning display and is held in place by two mounting screws on the rear of the LCD panel.
I purchased some new speaker grill cloth from Amazon and remade the speaker grill front with cut outs for the speakers. It looks really tidy and matches the rest of the bakelite cabinet nicely.
1946 Philips 170A-15 Shortwave Receiver RadioBerry HAT on RaspberryPi 4
To finish the project off I need to purchase 3 rotary encoders so that I can have a VFO knob and two more knobs for other things (to be determined). The Volume control is already in place with the original knob fitted to it. It will be nice to complete the 4 knob line up.
I had to make a couple of fittings top and bottom to hold the original rear panel in place but, it worked out just fine and I only had to fit an SO239 antenna connector and ethernet RJ45 port so that it can be connected to my local LAN.
Receiving radio Caroline on 648Khz
The audio quality from the little RadioBerry and 15w amp is pretty good. With the speakers hidden nicely behind the refurbished speaker grill the project looks quite tidy!
It also makes a great receiver for the HAM bands with it’s coverage of 100Khz to 30Mhz.
The DL1YCF Enhanced fork of PiHPSDR works really well on the touchscreen and provides a modern control interface to the RadioBerry HAT.
Listening to the 20m HAM Band
I’ll drop a final article once I have purchased the 3 rotary encoders to fill the 3 remaining holes in the front of the cabinet.
For the last week or so I’ve been playing with a RadioBerry HAT for my RaspberryPi computer. The RadioBerry is a cut down version of the Hermes Lite 2 with just 20mW output power and separate TX and RX antenna ports. It’s a really neat little package that sits on top of a RaspberryPi4/5 and creates a neat little HF transceiver.
RadioBerry HAT
I initially started with the RadioBerry HAT on my Pi5 but, I soon realised that the software really doesn’t work well at all on the Pi5. I’m not 100% sure as to why but, for some reason it holds one core at 100% continuously. It seems that the RadioBerry software is single threaded. The end result is that on the Pi5 you cannot use a sample rate above 9600 before the IQ stream starts to stutter.
By contrast, installing the RadioBerry software onto a Pi4 it performs perfectly upto the maximum sample rate of 384000 without any stuttering. I’ll need to spend some time going through the source code to try and determine why it doesn’t work correctly on a Pi5.
Whilst going through the source I discovered that the developer has put some code in that collects data from the running computer and sends it to the developer’s website. Some of this data is then made public via his website, http://www.pa3gsb.nl/radioberry/api/read.php
One of the things displayed on the website is the Mac address of the RaspberryPi on which the RadioBerry is running. This is a security risk and should never be done!
The most annoying thing is that this is done without authorisation. The installation doesn’t state that it’s going to collect data every time you start your RaspberryPi computer nor does it offer the ability to opt out. It also doesn’t inform the user that it’s going to pass the data on to a third party. In some cases it even collects HAM Radio Callsign and location data and displays it on a public website, a clear breach of the UK/European Data Protection Law.
Finding spyware in open source software is really poor and something most open source developers would never consider doing.
To this end I have disabled the spyware in the version of the RadioBerry software that I am using and am making it available to everyone else to use via this blog.
So, to install the RadioBerry software you just need to download the installation script and run it in a terminal on your RaspberryPi computer.
The script will download the modified source code, compile it and install it on your RaspberryPi ready for you to use.
I encourage everyone that downloads the script and the source code to take a look at it and ensure you are happy with it. It’s important to know what you are running on your computer and what it does.
You can find the spyware code in the register.c file (It’s all commented out with “//” marks). The function now doesn’t pass any data at all to the public website.
I hope some of my readers who are experimenting with the RadioBerry transceiver find this useful.
I will soon be publishing an article on an enhanced version of PiHPSDR from DL1YCF to use with the the RadioBerry to complete the project.
Important Update:
There is an issue with the RadioBerry code that renders it useless if you use a kernel later than the version shown below:
Updating the O/S Kernel to any version later than the version shown above will stop the RadioBerry software from working. Recompiling of the code also fails due to the Kernel update and at the time of writing this cannot be fixed without a code rewrite by the original developer.
I also recommend that once you have built a working RadioBerry on a RaspberryPi 4 you should disable the automatic updates of the O/S to stop the system from failing in the future.
You can disable the automatic updates by entering the following commands into a terminal:
This antenna modelling session came about after a conversation with Michael, DK1MI on the Matrix. I believe the antenna design was originally done by Artur, M0PLK with reviews being on EHAM.
The antenna takes the form of a simple inverted triangular loop with a 5.8m flat top and two diagonals each 5.6m long coming down to a point. The antenna is fed in the centre of the flat top with 450 Ohm open ladder line and a 4:1 Balun. This antenna will require an ATU on all bands as the modelling shows a very wide range of impedances at the feed point.
Multi-Band Delta Loop Antenna View
The design seems to suggest using two fixed aluminium tubes with the wire fed up through them for the two diagonal elements of the antenna however, it would probably be easier to use a pair of collapsable fibre glass poles (Not Carbon fibre) with the wire attached via some clips or tape.
I decided to model the antenna with the top horizontal wire 10m above ground putting the point of the triangle 5.2m above ground. I felt this was an achievable height for most HAMs. Lowering the antenna will raise the resultant angle of maximum radiation on all bands.
Looking at the 2D Far Field Plots (2DFFP) the antenna radiates through the loop as expected with a higher radiation angle on the lowest band and the lowest radiation angle on the highest band. The antenna is of course bi-directional and so could be rotated just 180 degrees to obtain global coverage.
On the 30m band the antenna has a very high angle of maximum radiation making it ideal for short distances. There is a little gain to be had at 25 degrees however, this is nowhere near the maximum but, will possibly aid working longer distances. A maximum gain of 5.31dBi is obtained at 72 Degrees on the 30m band.
Multi-Band Delta Loop Antenna 30m 2D Far Field Plot
On the 20m band the 2DFFP is fairly similar to that of the 30m band but, with 5.57dBi gain at a lower angle of 34 Degrees. This will provide excellent results on medium distance contacts and reasonable results on the long haul.
Multi-Band Delta Loop Antenna 20m 2D Far Field Plot
Once above 14Mhz things start to get more interesting. From the 17m band upwards the radiation pattern changes quite drastically and starts to provide some excellent gain at relatively low angles. This will improve the antenna’s DX performance considerably on the higher bands.
Looking at the 17m band the angle of maximum radiation is now down to 26 degrees with a gain of 7.64dBi. At 12 degrees there is a gain of 4.59dBi. This radiation pattern will make this antenna ideal for the medium to long haul contact with very little interference from NVIS signals.
Multi-Band Delta Loop Antenna 17m 2D Far Field Plot
The 15m band follows the trend with the angle of max radiation now down to 22 degrees with a max gain of 8.54dBi. Even at 10 degrees there is a gain of 5.34dBi which will be very welcome for DXing. There is slightly more near vertical incident skywave (NVIS) radiation on the 15m band and so the antenna should provide short, medium and long haul contacts with the latter being favoured.
Multi-Band Delta Loop Antenna 15m 2D Far Field Plot
Moving up to the 12m band the angle of maximum radiation now comes down to 18 degrees with a gain of 8.61dBi. There is also 5dBi of gain to be had at 8 degrees which is ideal for DXing. Unfortunately there is slightly more NVIS radiation on the 12m band than there is on the 15m band. I’m sure with a little change in height this could be reduced such that the antenna provides only low angle radiation.
Multi-Band Delta Loop Antenna 12m 2D Far Field Plot
Finally we reach the 10m band, this is where the antenna has the lowest angle of maximum radiation. With 8.56dBi gain at 16 Degrees, 5.59dBi at 8 degrees and a much reduced NVIS radiation. This antenna should be excellent for the long haul on 28-29Mhz. (It would also make an excellent 11m/CB antenna).
Multi-Band Delta Loop Antenna 10m 2D Far Field Plot
It’s interesting to note the similarities between this multi-band delta loop design and my Bi-Directional Slot Fed Antenna design. They both exhibit very similar radiation patterns and gain figures with the Slot Fed Antenna providing slightly more gain and an even lower angle of maximum radiation on the supported bands.
Overall this easy to construct multi-band delta loop antenna would be ideal for the HAM that just wants a single antenna for 30m and upwards or is looking to go portable. The only disadvantage is that a good Remote Auto ATU is required to provide matching of the antenna to the 50 ohm coax at the feed point. Something like the LDG RT100 would be an ideal ATU choice for this application and would remove the losses caused by having a high SWR on the coax feed to the antenna.
Using an ATU in the radio in the shack isn’t going to provide the same results as the coax cable from the antenna to the shack will become part of the antenna and will be detrimental to the antenna performance. It will also create high losses on the coax feed to the antenna due to high SWR being present over the length of the coaxial feed.
Following on from the article I wrote about the performance of my multi band vertical antenna I’ve now put together a table showing it’s performance on each band as experienced over a period of 18 months.
It’s interesting to note the antenna wavelength measurements on each band as 13m (43FT) seems to be an almost perfect length for a simple multi band vertical HF antenna with excellent DX capabilities.
M0AWS 13m (43FT) Multiband Vertical HF Antenna Info (Click to Enlarge)
Looking at the information you can see that performance on the 160m band is poor. This is to be expected as the antenna is far too short for a band with such a long wavelength. I knew this would be the case from the outset and never planned to use this antenna on the 160m band. I’ve included the data here just for completeness. If you’re looking for a reasonable 160m band antenna that can fit into an average UK garden then take a look at my Inverted-L antenna article.
Performance on the 80m band is surprisingly good considering the antenna is only 1/6th of a wavelength long. With contacts into Indonesia achieved using relatively low power levels this antenna surprised me with its performance on the 80m band. A 1/4 wavelength antenna would of course perform better but, like all multi band vertical antennas for the HF bands there is always a compromise.
On the 60m band the antenna is pretty much a 1/4 wave vertical, it works great on this band and I’ve had a lot of fun chasing DX in the winter months. With the longest contact being into Brazil at 6144 miles this antenna performs extremely well for such a simple design.
On the 40m band performance is better still. With the antenna being just over a 1/4 wavelength long the point of max current is above ground level making this a very good DX antenna. With multiple contacts into Australia at distances over 10,000 miles this antenna is the ideal 40m band DX chaser for small gardens.
Moving up onto the 30m band this antenna now begins to really shine. Being a half wave long on 30m the point of max current is half way up the wire lowering the angle of radiation considerably. This results in excellent global coverage with contacts into Australia being a breeze. With the longest distance achieved being 11,776 miles into New Zealand this really is the goto antenna for fans of the 30m band with small gardens. This antenna easily out performs my 30m band Delta Loop design whilst giving better global coverage.
On the 20m band this antenna performs very well indeed. Considering it’s 3/5th of a wavelength long which is a strange length to have, it’s no slouch. Global coverage is excellent and working into Australia is relatively easy. I’ve yet to work into New Zealand on the 20m band using this antenna but, that’s mainly due to me not being on air at the right times. Best distance worked so far on this band is 10,656 miles.
On the 17m band the antenna is 3/4 wavelength long. This is a very useful length and easy to tune as it presents pretty much 50 ohm impedance at the feed point. Performance is simply stunning on 17m, if you can hear the DX you can work them. I am amazed at how well this antenna works on this band. It seems to have a low angle of max radiation making it excellent for chasing DX stations. Giving me my first contacts into Alaska and New Zealand this is my goto antenna for the 17m band.
On the 15m band this antenna is 7/8th of a wavelength long. Performance doesn’t feel as good as it does on 17m but, with the longest distance achieved being 8023 miles there’s really no reason to doubt it. With only 87 contacts being made on this band due to the fact that I always get trapped chasing DX on the 17m band and never make it any further up the bands, I’m sure this antenna will perform extremely well long term on 21Mhz. I just need to make more effort to get on this band.
The 12m band is one of the bands I didn’t expect this antenna to perform well on. Being 1 and 1/8th wavelengths long it’s not a length that you would normally consider using for an antenna however, performance is excellent. This is most likely due to the point of max current being a fair way up the wire resulting in a low angle of maximum radiation. DXing is great fun with this antenna on the 12m band and it’s surprised me time and time again at how easily I’ve been able to work DX stations. With the best distance worked so far being into the Falkland Islands at 7973 miles, this antenna has huge potential on this band. Like the 15m band, I need to make an effort to spend more time on the 12m band and see how far I can push this antenna.
Finally we reach the dizzy heights of 28Mhz on the 10m band where the antenna is 1 and 1/4 wavelengths long. Again this is a useful length as it presents almost 50 ohm impedance at the feed point. DX performance on the 10m band is good. It’s probably very good however, like the 15m and 12m bands, I rarely make it up onto the 10m band and so I’ve not really given the antenna the time to prove itself at 28Mhz. My best distance worked so far on this band is 4872 Miles into the USA but, I’m sure I could easily do better if I committed more time to it.
I’ve pretty much covered all the good points of this simple multi band antenna so, now let’s look at the not so good points.
If you’re in the UK and are looking to work other UK stations then this antenna isn’t for you. Like all vertical antennas there isn’t much in the way of NVIS radiation and so you’ll find UK stations just won’t hear you. You’ll also often find you won’t hear UK stations at all due to the null at the top of the antenna that attenuates signals arriving from high/very high angles. For me this is fine as I wanted an antenna that was focused on DXing as much as possible.
From 10Mhz upwards the antenna also isn’t that good for working stations in nearby Europe. Most of the time you will only hear European stations that are more than 1000 – 1500 miles away, anything closer just doesn’t appear in the receiver. On the 15m and 12m bands often you will never hear European stations at all, only DX stations. This does of course reduce the QRM from UK/EU stations considerably making it easier to work those weak/QRP DX stations.
So as you can see, 13m (43FT) of vertical wire is probably one of the best lengths you can possibly use for a multi band vertical HF antenna especially if like me, you have a small garden to squeeze your antennas into. I don’t like to say it but, this could be the magical length we’re all looking for when making a multi band HF vertical antenna.
Tuning of the 13m (43FT) vertical antenna is achieved using my CG3000 remote auto ATU. I initially started off using my home-brew Pi-Network ATU but, changed over to the CG3000 so that in the winter months I don’t have to run out into the rain and wind to change bands. It’s important to note that the ATU must be at the base of the wire and not in the radio shack. It’s also important to note that I have 4 x 20m long radials connected to the CG3000 along with an earth spike at the base of the wire. This combination of ground and tuner works incredibly well with the ATU tuning on each band with ease in less than 3 seconds. I’ve also not had any issues with the CG3000 attempting to retune whilst in the middle of a QSO, once it’s initially tuned it doesn’t retune again until I either change band or make a large change in frequency.
The achieved SWR on all bands is <1.5:1 except for 160m where it is 1.8:1.
Since I put together my Inverted-L antenna and Pi-Network ATU I’ve been having a lot of fun on the low bands.
Getting back onto 160m has been most enjoyable and I’ve now had over 100 ‘Top Band’ contacts with distances covered as far as 3453 Miles into Sosnovoborsk Asiatic Russia.
I must admit I am amazed at the distances achieved on the 160m band as the antenna isn’t very high above ground level when compared to a single wave length on 160m.
M0AWS Inverted-L Antenna View
The Inverted-L antenna at the M0AWS QTH was designed purely around the size of the back garden. Using a couple of 10m Spiderpoles the vertical section of the antenna is 10m tall and the horizontal section is 28m long. Naturally the antenna resonates around 2.53Mhz but, can be tuned to resonate anywhere on any band using the Pi-Network ATU I built that is situated at the base of the vertical section of the antenna.
Looking at the far field plots for the antenna on each band we see that as we move higher in frequency the radiation pattern becomes more complex and the radiation angle gets lower, exactly what we would expect from such an antenna. The antenna runs pretty much North/South in the garden ( X axis on the diagram above) and so we would expect the antenna to radiate East/West (Y axis on the diagram above) however, this isn’t always the case.
M0AWS Inverted-L Antenna 160m 3D Far Field PlotM0AWS Inverted-L Antenna 160m 2D Far Field Plot
(Click Far Field Plots for full screen view)
On 160m the antenna favours the South (-X Axis) and presents some usable high angle gain although, from using the antenna you would never know this to be the case as it seems to have pretty good all round coverage. With the best distance of 3453 Miles being covered to the East into Asiatic Russia the antenna performs well even though the far field plot is slightly biased to the South.
M0AWS Inverted-L Antenna 80m 3D Far Field PlotM0AWS Inverted-L Antenna 80m 2D Far Field Plot
On the 80m band the Inverted-L antenna becomes a cloud warmer and exhibits very high angle radiation. On 80m the antenna is ideal for NVIS Inter-G propagation and is great for rag chewing with other UK/Near EU stations.
M0AWS Inverted-L Antenna 60m 3D Far Field PlotM0AWS Inverted-L Antenna 60m 2D Far Field Plot
Looking at the far field plots for the 60m band once again the antenna provides lots of high angle gain however, there is also some very useable lower angle gain that has proven to be excellent for working long hauls into North America and east into Central Asia. On the 60m band during the day the antenna is excellent for Inter-G chatting, using just 20w-40w I can very easily chat with other UK HAMs even when the band is noisy.
M0AWS Inverted-L Antenna 40m 3D Far Field PlotM0AWS Inverted-L Antenna 40m 2D Far Field Plot
Moving on up to the 40m band we find the far field plot starts to get a little more complex. Looking at the 3D plot you’d think that the antenna favoured the South (-X Axis) however, in reality it favours the NorthWest with both some high and low angle gain. This antenna has proven to be excellent for DXing into North America on 40m but, has also been great for DXing into South America getting great signal reports from stations in Panama at a distance of 5415 Miles. During the day NVIS propagation is excellent and I find I can chat with other UK and near EU stations with ease using just 25w.
M0AWS Inverted-L Antenna 60m/40m Global Coverage
Above is a screen shot from PSKReporter showing stations that have heard me on the 40m and 60m bands. As you can see, global coverage is excellent with stations as far as Australia and New Zealand hearing me on the 40m band and stations on the West Coast USA hearing me on the 60m band. I was also pleased to see I was heard in Africa on both bands, a region of the world I would like to get more contacts from.
M0AWS Inverted-L Antenna 30m 3D Far Field PlotM0AWS Inverted-L Antenna 30m 2D Far Field Plot
On the 30m band the Inverted-L antenna starts to exhibit two lobes with gain to the NorthEast and NorthWest. This makes the antenna ideal for working into the USA and Australia/New Zealand over the North Pole. Working US stations is a breeze with relatively low power and I almost got a contact with New Zealand during the evening greyline but, unfortunately the DX station dropped out before I managed to get my signal report back to him. As time goes on I’m sure the antenna will more than prove itself on the 30m band.
So far I’ve not ventured above the 30m band with the Inverted-L antenna as I’ve really been enjoying access to Inter-G chats on 80m, 40m and 60m and chasing DX on 160m, 60m, 40m and 30m. I need to venture up onto the higher bands before the long winter nights settle in and the higher HF bands close for the winter season.
Looking at the far field plots on the higher HF bands the antenna has huge potential as it provides some nice low angle radiation in useful directions.
M0AWS Inverted-L Antenna 20m 3D Far Field PlotM0AWS Inverted-L Antenna 20m 2D Far Field Plot
On the 20m band the far field plot starts to get much more complex with lobes at many different angles. The main gain lobe is to the NorthEast towards the USA and is at a fairly low angle and so this antenna should be great for working stateside on the 20m band. There are also lobes to the NorthEast and so hopefully working VK/ZL over the pole should also be possible. As I said above I’ve not yet used the antenna above the 30m band and so at this time cannot confirm performance but, it looks promising.
M0AWS Inverted-L Antenna 17m 3D Far Field PlotM0AWS Inverted-L Antenna 17m 2D Far Field Plot
The 17m band also looks promising with a similar far field plot as the 20m band but, with lower angle of maximum radiation and more gain. It will be very interesting to test this antenna on 17m especially since the noise level is below S0 and I can very easily hear the weakest of stations on this band.
M0AWS Inverted-L Antenna 15m 3D Far Field PlotM0AWS Inverted-L Antenna 15m 2D Far Field Plot
Once again the 15m band looks very similar to the 17m band, low angle radiation but, with a slightly more complex far field plot.
M0AWS Inverted-L Antenna 12m 3D Far Field PlotM0AWS Inverted-L Antenna 12m 2D Far Field Plot
The 12m band far field plots continue the theme with the angle of maximum radiation slightly lower than on the 15m band and slightly more gain. This antenna should be great for chasing the DX on the very quiet 12m band.
M0AWS Inverted-L Antenna 10m 3D Far Field PlotM0AWS Inverted-L Antenna 10m 2D Far Field Plot
Finally the 10m band is very similar to the 12m band in that the far field plots show low angle gain albeit with an even more complex radiation pattern.
I originally put this antenna up so that I could work Inter-G on the low bands but, it has proven to be a much more worthy antenna than I originally thought it would be. I need to spend more time with this antenna on the bands above 30m to really see how it performs on the higher HF bands but, so far I’m really pleased with it’s overall performance on all the bands tested to date.
I can highly recommend using FT8 to test new antennas. With PSKReporter and my own NodeRed World Map WSJT-X interface I can see realtime the antenna performance on each band. FT8 is an extremely useful tool when it comes to testing antennas to see if they perform as per the modelling and can often provide some performance surprises!
The bi-directional slot fed HF antenna isn’t mentioned very often these days for some strange reason. It’s a real shame as it is an excellent antenna that gives high gain through the loop between the frequencies of 14Mhz and 29Mhz.
M0AWS 20m – 10m Slot Fed HF Antenna
Construction of the antenna is relatively simple, 3 x 3m long horizontal wires and 2 x 9.2m long vertical wires. I’ve modelled the antenna using 20mm diameter copper tubing for the horizontal conductors and 2.5mm wire for the two vertical conductors. Using the 20mm copper tubing provides a rigid platform for the mounting of the antenna on a non-conductive mast whilst reducing weight by using 2.5mm wire for the vertical conductors. You could of course use 20mm copper tubing for all the conductors if you have a non-conductive mast that can handle the weight.
An alternative option is to hang the antenna from a high tree and secure it in position with non-conductive nylon cord. This works very well and makes it extremely easy to manually rotate.
The antenna is fed at the centre of the middle horizontal tube (conductor 2 in the image above) using one of the following methods:
Method 1 – Use a 4:1 Balun and ATU either in the radio/Radio Shack or connected directly to the Balun. Connecting a remote auto ATU to the balun directly at the feed point is the best option as you will then have a perfect 50 Ohm impedance match to the coax cable going back to the radio. (I’ve used my AH-705 and a 4:1 Balun at the feed point in the past with excellent results).
Method 2 – Connect a remote auto ATU directly to the feed point of the antenna and then 50 Ohm coax back to the radio shack. This will provide a perfect SWR match on all bands and works extremely well. (I’ve used my AH-705 remote auto ATU in this configuration as well in the past, again with excellent results and no discernible difference to method 1).
Method 3 – Feed the antenna with 450 Ohm open ladder line and use a 4:1 Balun and ATU in the radio shack to match the antenna to 50 Ohm radios. It’s important to bring the 450 Ohm ladder line away from the feed point horizontally and not vertically downwards. This will then help to protect the radiation pattern.
Looking at the 2D Far Field Plots this antenna provides excellent gain at relatively low radiation angles on all bands 20m – 10m making it an ideal antenna for chasing DX.
20m Band 2D Far Field Plot 17m Band 2D Far Field Plot 15m Band 2D Far Field Plot 12m Band 2D Far Field Plot 10m Band 2D Far Field Plot
The gain on each band is as follows:
20m Band – 7.83dBi at 24 Degrees 17m Band – 9.07dBi at 20 Degrees 15m Band – 9.63dBi at 16 Degrees 12m Band – 10.36dBi at 14 Degrees 10m Band – 10.99dBi at 12 Degrees
10m Band 3D Far Field Plot
The 10m Band 3D Far Field Plot above shows the typical radiation pattern for the antenna. Maximum radiation is through the loop with very little high angle radiation making it ideal for chasing DX stations. Gain increases as frequency increases however, angle of maximum radiation decreases as frequency increases improving DX capability of the antenna on the higher bands. It’s worth ensuring that the antenna is rotatable as this will then enable you to point the antenna at the DX station to maximise signal strength at the DX end. Pointing this antenna North/South makes it great for working VK/ZL over the North Pole whilst at the same time being able to work South Africa from the UK.
Summary:
Horizontal Wire Lengths: 3m @ 20mm Diameter Vertical Wire Lengths: 9.2m @ 2.5mm Diameter Modelled Height above ground at Centre (Conductor 2): 10.6m Feed Type: 4:1 Balun + ATU / Remote Auto ATU / 450 Ohm Ladder line with 4:1 Balun & ATU
Over the years I’ve built many multi band vertical HF antennas including multi-element quarter wave verticals like the DXCommander configuration, multiple end fed vertical dipoles all on the same pole and a host of other configurations. As with all multi band antennas there’s always a compromise, on some bands it performs well and on others it doesn’t, it’s the nature of the beast.
For some time now I’ve been using a multi band vertical antenna that has over the last year performed incredibly well on all bands from 80m to 10m. Don’t get me wrong, it’s not perfect however, it has out performed every other multi band HF vertical I’ve tried to date even though it’s by far the simplest antenna design and according to the antenna modelling software I have it shouldn’t be as good as it is.
So what is this magical multi band HF vertical I speak of? Well it’s nothing more than a piece of wire 13.4m long taped up a 12.4m vertical Spiderpole with 1m of wire tucked down into the top of the Spiderpole.
Obviously this is not going to be resonant on any band without some sort of impedance matching circuit at the bottom of the wire. Originally this antenna was my end fed half wave vertical antenna for the 30m band that was fed via a 49:1 Unun. This antenna worked incredibly well on the 30m band allowing me to work DX globally with ease but, it was a single band antenna and I wanted a multi band solution.
I decided to remove the 49:1 Unun and replace it with a home brew LC circuit made up of a coil made from 5mm copper tubing and a large air spaced variable capacitor I had laying around from an old ATU project I built many moons ago.
This simple LC arrangement at the bottom of the wire worked incredibly well and tuned the wire from 80m to 10m with a perfect SWR on each band using nothing more than a ground rod and 4 x 12m radials. Performance was surprisingly good on all bands 80-10m giving me the ability to get some DX stations that I’ve never been able to hit before. The only drawback to this solution was the fact that I had to go out and manually tune the antenna every time I wanted to change band. Not so much of a problem in the summer but, in the winter in the pouring rain and howling wind it’s no fun at all. (I resolve this issue further down in the article!)
Multi Band Vertical HF Antenna using a 12.4m Heavy duty Spiderpole at the end of the garden
Performance on the HF bands is incredibly impressive with this antenna. Modelling it on EzNEC software it shouldn’t be that great on bands above 20m however, it seems to defy the modelling software as it performs amazingly well on 17m, 15m and 12m, better than any other vertical antenna I’ve made for those bands. How this can be I do not know, normally my antenna builds match closely what the modelling software shows but, in this instance it doesn’t and I’ve really no idea why.
Multi Band Vertical HF Antenna showing loop at top and wire tucked down into pole
Always wanting to put things into perspective here’s some details of the contacts I’ve made on each band showing how well this antenna has performed over the last year or so.
Firstly the 80m band, I’ve not used this band much over the winter months as I’ve got into the higher bands however, the map below shows all the stations worked on 80m using this antenna.
Stations worked on the 80m band from the M0AWS QTH
There are 51 contacts in total, not a big number by any means however, there are some good distances made with contacts into North America, South America and Indonesia. I’m sure I could had done better if I’d spent more time on this band, something to aim for next winter perhaps.
Next is the 60m band, a band I really like and have enjoyed over the winter months. The antenna performs incredibly well on this band even though we have very limited access to 60m here in the UK. With 288 contacts in the log with a good spread of distances I’m really pleased with how this antenna performs on this band.
Stations worked on the 60m band from the M0AWS QTH
Moving up in frequency the 40m band is the next one on the list, this is a great band and one that I’ve loved for many years. I’ve spent countless hours on CW on this band in the past and worked some great DX. The performance of this antenna on the 40m band is excellent, if I can hear the DX normally I can work them regardless of where in the world they are located. With 226 contacts in the log spread globally over the winter here in the northern hemisphere I have no complaints about performance of this antenna on the 40m band.
Stations worked on the 40m band from the M0AWS QTH
Moving up onto the 30m band I have to admit this is probably my favourite band of all. I’ve spent so many hours on CW working some of the best fists I have ever heard on the air I’ve grown to love this band not just for the DX available but, for the quality of operator found on this narrow piece of the RF spectrum. Needless to say since the antenna is a half wave on the 30m band performance is stunning, out performing any other 30m band antenna I have ever made. It’s even better than the 30m Delta Loop antenna that I built and used when I lived in France.
With 467 contacts in the log on the 30m band you can tell this is my goto band and one that offers access to some of the best DX in the world.
Stations worked on the 30m band from the M0AWS QTH
The 20m band is a band that I never really used until I moved back to the UK from France. Living in France I had acres of land and so I was very much into the low bands, 160m to 30m and never ventured above this part of the spectrum. Now living back in the U.K. with a typical U.K. sized garden the low bands are much more difficult to get onto and so my interests have moved up in frequency somewhat.
Getting onto the 20m band I was amazed at how easy it is to work DX stations compared to the low bands, it’s simply a case of if you can hear them you can work them, there’s no real challenge to be honest. Because of this the band is always super busy with people shouting over the top of each other to get the DX. Not to be put off, I’ve made a surprising 412 contacts on 20m covering the globe. This antenna works incredibly well on this band and you really don’t need anything else to work DX on 20m.
Stations worked on the 20m band from the M0AWS QTH
Next is the 17m band, one of the WARC bands that I’ve never really ventured onto until now. I have to admit I really like this band, when it’s open it’s normally open to the world all at the same time. With an almost undetectable background noise level you can hear the faintest of signal on this band. This is one of the bands that according to the EzNEC modelling software this antenna shouldn’t be any good on but, I have to say that it’s performance is beyond anything I ever imagined. I’ve worked my longest distance yet on this band and with this antenna, ZL4AS at 11776 miles, a distance I haven’t achieved yet on any other band. The 17m band really is a great band, I’d actually say it’s better than the 20m band even though there is considerably less spectrum available. With 220 contacts in the log it’s been a fun band to use.
Stations worked on the 17m band from the M0AWS QTH
Continuing the theme of the WARC bands, the 15m band is another one that I’ve only discovered in the last 12 months. It’s only now that I realise what I’ve missed out on due to my addiction to the low bands for so many years.
I’ve only made 76 contacts on the 15m band, not a lot at all really. This is mainly due to the fact that I get easily side tracked by the 17m and 30m bands most of the time and the radio VFO never gets as far as 21Mhz. Performance of the antenna is good on 15m, I would say not as good as on the 17m band but, it’s no slouch by any means.
As you can see on the map below, I may of only made 76 contacts on the 15m band but, they are spread right across the world proving that this antenna’s DX-ability on 21Mhz really is rather good.
Stations worked on the 15m band from the M0AWS QTH
Finally we arrive at the top of the WARC bands, the little 12m band. Once again this band is very much like the 17m band, super low background noise level, when it’s open you can work huge distances with very little power but, often there is quite deep QSB that can make getting that elusive DX a bit more challenging.
With only 66 contacts in the log once again I’ve not spent a huge amount of time on this band but, it hasn’t disappointed. With global coverage from this antenna on 12m once again I am astounded at how well it works. With software modelling saying it should be terrible on 24.9Mhz with nothing but super high angle radiation, it really shouldn’t be a good antenna for DXing on this upper WARC band but, it is and I have no idea as to why!
Stations worked on the 12m band from the M0AWS QTH
Finally we arrive at the 10m band, another band that I have never got into even though many refer to it as the magic band. This is the band that I’ve made the fewest contacts on, not because the antenna doesn’t work at the dizzy heights of 28Mhz but, because I hardly ever get the VFO dial past the lower bands due to the level of DX available. I really should make more effort to get the best out of the 10m band, especially now the summer is coming.
With a measly 19 contacts in the log I should be ashamed of myself for not doing more on this band as it is very often open and busy with traffic. Since I’ve not really used the antenna that much on the 10m band it’s hard to say how well it performs however, I have had contacts into North and South America and so it shows potential.
Stations worked on the 10m band from the M0AWS QTH
As you can see, the performance of this antenna is self evident from the log entries, it works superbly even though the modelling software says it shouldn’t above 14Mhz. This is now my main antenna here in the U.K. and I’ve only made one change to the initial setup and that is to add a CG3000 remote auto ATU to replace the home-brew LC tuning circuit.
CG3000 Remote Auto ATU housed in a plastic box
With the CG3000 auto ATU in place I no longer have to venture out into the cold, wet garden in the winter months to change band, it’s just a case of sending a continuous 10w signal into it and leaving it to tune in less than 2 seconds. The CG3000 is a Pi Network ATU so it handles both high and low impedance loads with ease. A Pi Network ATU is one of the best you can have, I’ve made my own in the past and had excellent results.
So in summary, 13.4m of wire vertically up a 12.4m pole with 4 x 12m radials, a ground rod and a CG3000 Auto ATU will give any HAM station the ability to work DX on all bands from 80m to 10m without ever having to leave the shack to tune it.
Since I got the CG3000 off of Ebay for a bargain £170 and the 12m heavy duty Spiderpole for under £100 the total cost of the antenna is considerably less than many commercial offerings available and yet performs as well if not better.
If you want to get this antenna onto the 160m band then you just need to add a small coil into the mix at the bottom of the wire to increase the inductance in circuit. The CG3000 will then happily tune the entire 160m band. It’s best to remove this coil though for all the other bands otherwise performance is reduced.
Please be aware that the performance of this antenna will not be anywhere near as good if you use the ATU in your radio at the end of a coax run. This is because the coax becomes part of the antenna and the radiation pattern is all but destroyed. You will be extremely disappointed if you use the antenna in this fashion. The ATU must be at the end of the wire and connected directly to ground and the radials to get the performance that I have experienced.
Finally, if you have an Icom IC-705 and AH-705 remote auto ATU you can use the AH-705 ATU in place of the CG3000, you will get the same results as I have with the CG3000.
I have used my AH-705/IC-705 combo quite a few times with this antenna with excellent results although, the big antenna can sometimes result in the receiver of the IC-705 getting overloaded especially on the lower bands. This is easily resolved by reducing the RF Gain on the radio.
For the last 24hrs I’ve had the RaspberryPi2 transmitting WSPR on 20m and 10m connected to my EFHW Vertical antenna. So far not a single spot on the 10m band, I’m assuming the band hasn’t opened in the UK over the test period.
WSPR 20m band reports over the last 24hrs
Results on 20m continue to impress with reports from the USA, West Africa coast and as far east as Georgia.
I’ll check the signal on 10m later today using my IC705 to ensure it is transmitting ok and then will leave it running for another 24hrs to see what happens.
UPDATE:
It appears there’s been a reliable opening on both 10m and 20m to the Canary Islands just off the west coast of Africa so far today.
The last 48hrs looks like this:
10mW WSPR from M0AWS JO02QC on 10m and 20m bands
More soon …
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