RE: FW: Loop on roof or in garden?
For receive only, I performed some experiments a few years ago with a 2 meter diameter untuned loop consisting of 1/2 inch water copper pipe and minicircuits balun(s) interfacing to the coaxial cable. Cable(75 ohm RG-6 Quad shielding) had large ferrite beads or alternatively, multiturns on large diameter toroids at both ends. Outside of the house at ground level, rooftop, and on a 12 meter tower. Main concern was the EMI emissions from TV's, PC's flourescent lights etc. in a suburban high density housing tract.
For EMI, it was worse at ground level (2-5 meters from the house). Less EMI on the rooftop (5 meters above ground) and least EMI on the tower. That was LF through 30 MHz.
As far as signal strength of LF beacons and local MW broadcasters, the signal strength was best at ground level measured at about 2-6 dB higher than at the tower elevation.....however, the EMI was also much higher. For SW above about 4-8 MHz, signal strength of ham and broadcasters was higher on the rooftop as well as even higher on the tower.
Hope this helps
---In email@example.com, <firstname.lastname@example.org> wrote:
With a friend I am in the process of building a magnetic unturned active loop of about 1 meter diameter for each of us for general and ham band listening.
I have often seen remarks that these loops perform best at a few meters above ground level.
Has anyone got any experience with the use of this type of antenna on a rooftop.
We have the option of placing this antenna on the flat concrete roof of a flat building of about 30 meters height, any advice?
How would this compare with the positioning of this same antenna on the balcony railing somewhat lower?
I hope someone can fill in the voids in my own experience.
Does it means that you advise to put the antenna high on the roof instead of somewhat lower on the balcony?
We will certainly compare the two situations after completion of our loops.
The amplifier we will use is not decided yet, I’m going through all the designs I have been able to find up to now. I do not have an education in electronics so I have to rely on what others mention about the subject.
Thanks for your reaction.