Hello everyone. Long time member here...somewhat at least. I have a question with a dilemma that is somewhat haunting me. I own a Pixel loop currently up 22 feet attached to a rotor. I tried to read up on loops and their distinct personalities and this question still remains. I have a weird sized backyard and located in a HOA. My backyard is elongated...roughly 15 by 45 feet. No real interference in my neighborhood since plasmas are "old school" and like I said no real RFI. Since I reside in a single story the tiptop of my house is at 22 feet,,,roughly. My loop extends maybe 4 feet or so over the top, since I have the mast attached to the side of my house near the backyard, It somewhat fits in with the many dish antennas that are in the neighborhood. THE QUESTION is my antenna too high? I figure it is just over the top of the roof.for line of sight...am I missing the picture here? I cannot picture mounting it 5 feet or so high off the ground in the back since then the house would block signals(I'm sure). I don't know so this is why I posted and hopefully put my mind to rest!
Ideal height for the Pixel loop
- Thread starter MisterLongwire
- Start date
- Status
ridgescan
Member
Nope. My Wellbrook is at 50' and I get tons of stuff and it is still quite directional. I have learned here that they like it better close to earth-but if you cannot do it, height doesn't hurt it from my own experience.
Those Pixels are nice-I see HRO started carrying them.
The small loop performs well close to ground, so just a few feet or so is adequate. In fact, up very high, the reception pattern narrows into a cloud-burner.
Placing it high however does give you line-of sight reception and allows you to clear large objects that can detune the loop, and further away from noise below.
However, if for some reason your loop is unbalanced, commonly having common-mode coax braid current, the antenna is really more of a vertical with a lollipop on the end.
With loops placed high, I definitely would want to ensure common-mode coax shield rejection with ferrite decouplers, 1:1 rf chokes - like an mfj 915 up near the feedpoint. Ideally a loop shouldn't have this problem, as it indicates something going wrong inside the preamp / tuning box.
You can detect common-mode issues by rotating the loop, and if you don't get two distinct nulls with about the same notch depth 180 degrees apart from each other, then you may have common-mode issues.
From a local noise-nulling standpoint, the null/notch depth is deepest perpendicular to the loop, and if raised much higher than the noise-maker, you may not achieve much of a null. Lowering the loop to be more inline with the noise generator may help you achieve the highest null depth.
If your location is already blessedly quiet, you can also determine if you have common mode problems by enlisting the aid of a friend, and with a *battery* operated drill motor located across the premesis, have them pull the trigger on the drill and rotate your loop. If you can't null it, you have a vertical antenna - OR the loop is so much higher than the noise source that it can't do a decent job.
So don't be afraid to lower the loop - as long as you aren't depending on line-of-sight communications.
Placing it high however does give you line-of sight reception and allows you to clear large objects that can detune the loop, and further away from noise below.
However, if for some reason your loop is unbalanced, commonly having common-mode coax braid current, the antenna is really more of a vertical with a lollipop on the end.
With loops placed high, I definitely would want to ensure common-mode coax shield rejection with ferrite decouplers, 1:1 rf chokes - like an mfj 915 up near the feedpoint. Ideally a loop shouldn't have this problem, as it indicates something going wrong inside the preamp / tuning box.You can detect common-mode issues by rotating the loop, and if you don't get two distinct nulls with about the same notch depth 180 degrees apart from each other, then you may have common-mode issues.
From a local noise-nulling standpoint, the null/notch depth is deepest perpendicular to the loop, and if raised much higher than the noise-maker, you may not achieve much of a null. Lowering the loop to be more inline with the noise generator may help you achieve the highest null depth.
If your location is already blessedly quiet, you can also determine if you have common mode problems by enlisting the aid of a friend, and with a *battery* operated drill motor located across the premesis, have them pull the trigger on the drill and rotate your loop. If you can't null it, you have a vertical antenna - OR the loop is so much higher than the noise source that it can't do a decent job.
So don't be afraid to lower the loop - as long as you aren't depending on line-of-sight communications.
Last edited by a moderator:
Like I said if I have it low such as 5 or 6 feet off the ground the house will block the signals. Thats why I have it a few overlooking the crown of the roof. FYI I am also using a rotor with it. Its times like this that I feel just throwing up a wire and calling it a day
To put your mind at rest, just go ahead and try it down low.
Yes, the house may attenuate signals in a certain direction, but with a loop we are not looking for signal strength, but *signal to noise* ratio. With no local qrm at your location, you should be able to have armchair-copy of signals that are attenuated by the house so that you don't even move the S-meter off the peg. And with no noise, you don't even need the rotator.
A small loop has a medium angle "take off" so to speak, about 22 degrees or so at the bottom, with high-angle fill in. The closest relative to that directional pattern with a regular wire would be an inverted-L containing both vertical and horizontal components, actually the vector sum of each, so it isn't really horizontally polarized, nor vertical. The small loop appears much the same for line of sight.
When you mount the loop down low, you actually IMPROVE the low-angle reception pattern, and this might overcome the attenuation being close to the house will do.
Fortunately, you don't seem to have any local noise, so if the house skews your loops directional pattern a little, you haven't lost anything since you aren't nulling any noise.
Note that I'm not talking about line of sight here. If that is your major concern, then by all means stay up high.
But don't take my word for it. Try it yourself, and report back what you find. At this distance, it is hard to give more than a generic answer, since each location has it's own variables.
Years ago I was completely astounded by being able to dx weak European 160 meter cw signals with only a 12 foot loop indoors under my metal shingled 1-story. And no preamp either! Signal-to-noise is what made that possible.
But this is all unproven internet anecdotal stories. Prove it to yourself before you throw up a longwire. And don't obsess over the S-meter - let your ears be your guide.
Yes, the house may attenuate signals in a certain direction, but with a loop we are not looking for signal strength, but *signal to noise* ratio. With no local qrm at your location, you should be able to have armchair-copy of signals that are attenuated by the house so that you don't even move the S-meter off the peg. And with no noise, you don't even need the rotator.
A small loop has a medium angle "take off" so to speak, about 22 degrees or so at the bottom, with high-angle fill in. The closest relative to that directional pattern with a regular wire would be an inverted-L containing both vertical and horizontal components, actually the vector sum of each, so it isn't really horizontally polarized, nor vertical. The small loop appears much the same for line of sight.
When you mount the loop down low, you actually IMPROVE the low-angle reception pattern, and this might overcome the attenuation being close to the house will do.
Fortunately, you don't seem to have any local noise, so if the house skews your loops directional pattern a little, you haven't lost anything since you aren't nulling any noise.
Note that I'm not talking about line of sight here. If that is your major concern, then by all means stay up high.
But don't take my word for it. Try it yourself, and report back what you find. At this distance, it is hard to give more than a generic answer, since each location has it's own variables.
Years ago I was completely astounded by being able to dx weak European 160 meter cw signals with only a 12 foot loop indoors under my metal shingled 1-story. And no preamp either! Signal-to-noise is what made that possible.
But this is all unproven internet anecdotal stories. Prove it to yourself before you throw up a longwire. And don't obsess over the S-meter - let your ears be your guide.
Last edited by a moderator:
I have had a Pixel loop up for about 3 years. The highest I have ever had it is about 10 feet in my backyard. Does not clear my roof line, but it works great, especially on lower bands, with very little noise. My Cushcraft R8 vertical on the roof does better on 18, 21, and 28 Mhz ham bands than does the Pixel, but not by much.
On the other hand, my Pixel has a much better S/N ratio below 14 Mhz. For about a year, I had the Pixel loop standing upright on at ground level in the backyard. Still worked very well, I was quite amazed. I have one Perseus running as a server, but that is hooked up to my R8 vertical antenna. Use the Pixel all the time with another Perseus, ELAD-FDM S2, and FCDP+. Works very well.
Steve AA6IO
On the other hand, my Pixel has a much better S/N ratio below 14 Mhz. For about a year, I had the Pixel loop standing upright on at ground level in the backyard. Still worked very well, I was quite amazed. I have one Perseus running as a server, but that is hooked up to my R8 vertical antenna. Use the Pixel all the time with another Perseus, ELAD-FDM S2, and FCDP+. Works very well.
Steve AA6IO
ridgescan
Member
hertzian great informative posts.
HF signals bounce of the ionosphere and downward. Mounting it down low is not going to "block" signals.
I would mount a few feet off the ground, but more importantly, mount it in the most open area possible with no metal buildings or objects.
We had one RR member mount his loop in the middle of his small garden. He painted the loop to match the surrounding "greens" in the garden. It worked quite well for him.
BTW, I have mine at 18ft with a rotator and I've used the rotator for may be all of (1) hour over the course of 2+ years.
Unless you hunt for MW DX you really don't need the rotator.
- Status
Similar threads
