Using state-of-the-art electronics and highly sophisticated instrumentation to perform detailed scientific tests, analytically comparing the relative performances of 2M Slimjim and 2M Dipole antennas, I once again headed out on my trusty motorcycle to meet my buddy Richie, MW0LGE on Twmbarlwm mountainside 1,100 feet up pretty much on the Southern edge of the South Wales valleys. The skies were clear, the sun was shining through the whispy clouds, and with it being around 19˚C, was more than comfortably warm for the time of year, all made for almost perfect conditions for some slash portable fun with amateur radio.
Hold on there a second John, I hear you say 😂… ok, ok, ok… maybe the equipment comprising a fibre glass pole, gaffer-tape, cable ties and a shiny Yaesu FT-70D isn’t quite the sophisticated electronic equipment my opening paragraph may have implied, and I admit I may have ever so slightly exaggerated, I nonetheless wanted to compare the operation of these two antennas out in the field to determine if there would be significant or at least noticeable performance differences between them. In summary, yes there did appear to be a difference, but this was not a huge amount, so if you’re interested, read on and let’s take a look at what I did, and if you’re not interested, well, thanks for reading this far.
Arriving just a little before Richie, who had far more more important things to do én route i.e. grabbing a McDonalds meal deal for us both, I initially set up the two antennas on the same pole which of course I should have realised isn’t conducive to accurate testing, and is what many seasoned experts will immediately spot as mistake number 1. Just for fun, and I suppose to prove how locating antennas in close proximity to each other can affect performance, we tested the SWR with an analyser. Image on the left shows the frequency where on the SlimJim antenna the SWR is closest to zero, and on the right, when I simply short across the connections on the PL259 of the Dipole antenna and once again find the frequency where on the SlimJim antenna the SWR is closest to zero. Not a massive difference in SWR (1:1 to 1:1.5) but interesting nonetheless. So, for further tests I borrowed another pole from Rich and set up the two antennas about 4M apart.
2M was pretty active yesterday and I had no shortage of responses to my CQ calls for help with testing, my thanks to everyone who did actually respond and help, much appreciated. Here’s a little table of some of those tests, and I think it’s clear to see which antenna seems to be the better performer. I guess this is no surprise as doing a little research and as advised by Ian, G4WUH (Wake Up Happy – great call sign, Ian), the SlimJim offers an apparent 2dB gain over a Dipole. This 2dB only really amounts to around a 1/3 of an S point, but with some QSO’s it did make that little bit of a difference from the SlimJim over the dipole, especially with Kevin, 2E1KJB on the Isle of Wight where for a short while I made almost 100 miles on 2M using the SlimJim whereas when using the Dipole it was not able to break squelch.
Made many more contacts over the course of the 5 hours we were there, and I simply must give an honourable mention to Eddie, M0LJT, who was not that far away from me over the Severn Estuary, in East Bristol. Eddie heard me making a few final calls later in the afternoon when things had gone a little quiet and kindly decided to reply when he advised me he had been listening to my calls for much of the afternoon and was led flat in bed after having broken three vertebrae in his back 2 weeks ago in a dreadful accident where he fell off a garden wall, landing dangerously on his head and is lucky to be with us. Eddie, if you read this sir, thank you so much for taking the effort and time to reply to me yesterday, it was a pleasure to chat with you. Together with everyone who may read this, I wish you a full and speedy recovery to what sounded like an horrendous injury, and I hope to catch you on 2M again very soon.
One other interesting contact was made earlier in the day whilst I was still at work, where I was having a discussion with a customer of my employer when it transpired was also a keen amateur radio user, Steve, M6DPS. Despite being on a ‘work call’, we had a great chat about all aspects amateur radio and thought there may be a chance of my making it to Clee Hill on 2M as I recently made contact with a chap in Craven Arms which is not that far from Clee Hill. Alas not, but it was a great chat on the telephone nonetheless, and it was great to meet you, Steve.
Steve is a keen YouTuber, his channel SPDTDL can be found here, please consider paying him a visit when you get a chance.
As I was busily having fun on 2M swapping between the SlimJim and Dipole, Richie had set up a vertical with only about 8 or so radials, and together with his IC-705 was making FT8 contacts all over the globe.
It is amazing what can be worked with 10W, top image is stations that copied his signal on 20m and bottom image is stations who copied his signal on 17m. I know he worked several stations across several of the HF bands from Finland to the USA. He did excitedly shout out… ” Yes, Brazil…..” at one point, but scoffed when he spotted the station was working someone else! Amateur radio eh!
In summary, I would have to say there isn’t a huge difference between the performances of the Slimjim and a Dipole for portable 2M work – however… if you only use the rubber duck antenna supplied with your handy when you are out portable, I would 100% recommend grabbing yourself either a home brew Slimjim, or Dipole for 2M – the difference using either of these compared to the rubber duck is orders of magnitude and will enable you to reach way further in your QSO’s.
The Slimjim did appear to be slightly the better of the two, but of course there are other considerations that were not taken into consideration that may have affected the performances of each. For example, phasing – where simply moving either antenna (or the source signal) 1m either way could have an effect on Rx/Tx, or even atmospheric conditions may have played a part i.e. managing to get almost a 100 mile QSO with Kevin on the Isle of Wight, will certainly have helped. After today I will quite likely still take both antennas with me when I head out on my motorcycle with the Yaesu, and if I end up at a quieter more private area, will probably use the Slimjim, and for quick contacts would use the clip on Dipole.
Either way it was another fabulously enjoyable afternoon, the McDonalds meal deal was tasty, the weather and company were great, and we were out in the sunshine making contacts enjoying our wonderful hobby that is amateur radio. I guess the lesson learned here, is to never underestimate the scientific value of fibre glass poles, gaffer-tape and cable ties, eh! 🤪
Enjoy folks, thanks for reading if you got this far, and if you did get this far I’d love to read any feedback you might have in a comment… and as always, keep safe.
John