CCW LAA++ - first impressions (long)
I’ve had my new CCW LAA++ for a number of weeks now and have given it an initial test drive. Ordering the loop from Chris was easy and problem free with the package arriving in a reasonable length of time here in Canada. Initially I am trying it indoors since this is where it might actually wind up as a final installation. It’s on the top floor of my house at a height of about 25 feet above ground. My receiver is an SDRplay RSPdx running SDRuno. I’m using the supplied bias tee with 12V from a linear power supply. On the shortwave bands I’m comparing it to my outdoor 65 foot long wire antenna. I live in a shallow valley which seems to be a bit of an RF sinkhole. Signals are not as strong at my home as they are in surrounding areas. There is also a high level of RF noise pollution which makes DX’ing the short wave bands a challenge.
As a first test I used the supplied 8 foot piece of wire. I hung it over a door frame which gave me sort of a misshapen five sided loop. The loop seems to pull in signals just as well as the wire antenna, if not better. Right across the whole shortwave band from 2MHz. to 30MHz. the CCW loop did well. The fact that I didn’t lose anything in signal strength with the much smaller loop was a relief.
The biggest difference was in how much quieter the loop is compared to the wire. This was demonstrated quite nicely on 17m with some French ham stations. They were easily readable on the loop but when I switched back to the outdoor wire they just dropped off into the noise. Cool! Even when there wasn’t much difference in signal levels between the two antennas the CCW loop was always more quiet, thus providing a much better signal to noise ratio. At some point I will build a better mount that will be rotatable so I can further investigate the nulling capabilities of this antenna.
The biggest surprise came in the 1.8MHz. to 3MHz. range. I’m surrounded by several 50kW medium wave stations which produce a variety of RF garbage that pretty much destroys reception in this range. This, plus all the urban electrical noise, renders it almost impossible to hear WWV on 2.5MHz. or ham radio operators on the 160m band. With the CCW loop all that changed and now WWV was coming in much more clearly, and I could now hear hams on 160m. With the addition of an MFJ-1026 noise reducer for further noise supression, reception on 160m is “almost normal” now.
The AM broadcast band was next. Signals coming out of the CCW loop amp were quite strong and overloaded my RSPdx, so I had to reduce gain by quite a bit. As the night progressed I noticed I was picking up stations much more easily than I had before on either the wire antenna or with a tuned passive ferrite loop that I had built some years ago for the AM broadcast band. Stations that I had regularly received before at poor to fair levels were now coming in much better. Just as a check I did a band sweep during the day so that signals were coming in via ground wave which made them more stable. Indeed the weaker ones were now more easily readable. This confirmed that the CCW loop was an improvement over my previous antennas. Again, on the AM broadcast band this antenna appears to be more quiet and seems to suffer less from all the high power RF garbage floating around. Everything just sounds “cleaner”, if that is a good way to describe it.
Up on the FM broadcast band the CCW loop also did well. I was now able to pick up more stations with better quieting than I had previously when compared to my vertical dipole. I’ve yet to test it much on the 6m and 2m ham bands, or the aircraft band but it seems to do well at least up to the rated 150MHz.
On the LF/VLF bands is where the CCW loop started to show some shortcomings. For the frequencies below the AM broadcast band my standard antenna for many years has been a Ralph Burhans untuned single turn shielded loop (approx. 3ft. in diameter) with a FET preamp. It is also located on the top floor of my house. In this comparison both loops were oriented the same way so that their nulls are pointing in the same direstion. There wasn’t a huge difference here but in general in the 200kHz. to 500kHz. range the Burhans loop was picking up non-directional beacons about 2-3dB better than the CCW loop. I also noticed that the Burhans loop was a bit better at rejecting low frequency noise. Further, with the CCW loop some of the AM stations were breaking through to a fair degree. This is not a fair comparison though as the CCW loop has no built in low pass filter. As the Burhans loop is specifically designed for the LF/VLF bands it does have a built in low pass filter so AM stations don’t make it through. I only mention this as a point of interest, not as one of criticism. Below 100kHz. things started to get worse on the CCW loop, but again this was not surprising as the CCW loop is only rated to 50kHz. For WWVB at 60kHz. the CCW loop was 8dB down, and by time we get to NAA on 24kHz. and NML on 25.2kHz. we are 15dB to 18dB down compared to the Burhans loop. As an experiment I made a little bit larger loop out of RG-59 coax to see if this would help but I didn’t notice much of an improvement. So the CCW loop is not an antenna one would necessarily use for reception in this frequency range. I would say if you are hunting NDBs the CCW loop is OK but it might benefit from a loop with a much larger capture area. As I don’t have the space indoors to do this it is not something I can test at the present time. And there is still the problem of AM station breakthrough, if that might be a problem for you.
So, as it stands, for short wave and medium wave in my RF polluted location the CCW loop did very well compared to the outdoor wire or my passive ferrite loop. It’s somewhat reduced performance below the AM broadcast band is not at all a deal breaker, so for me the CCW loop is a keeper. It improves my reception capabilities compared to what I had before. Further projects will be to try different loop configurations, or to get the loop out and away from the house, but for now I’m having great fun playing with this antenna as is.