|
Hi group!
?
If you're interested, I just uploaded the file "The Growing FLAG", which is a building instruction for my Rotable FLAG-antenna, which is somewhat smaller than traditional FLAG-antennas. I have been using this small antenna since the beginning of October 2024 on the MW Broadcast band, with surprisingly good results (conditions permitting).
?
73's
?
Hans / LB6GG
Sola, Norway
|
I would be very interested but I can't find the file.
|
Hello Mike,
look on this Website. PDF is under FLAG Antennas.( The growing FLAG Antenna)
https://www.dxinfo.se/
|
|
|
|
|
Hi Hans.
?
Can you verify this is actually the case: "In a passive splitter, there is a 6dB signal loss on each output and you may want to compensate for this loss, using a 6dB buffer amplifier."
?
A broadband resistive 'splitter' (not used much in practice today) may result in 6 dB loss, but a broadband CATV type transformer style results closer to 3 dB (half power) loss.
?
Thanks for the pdf too.
?
de Jim AA5CT
?
|
Hans,
?
Would there be any problem feeding the antenna and pre-amp with CAT-6 cable?
?
I read an article by a Canadian fellow that CAT 6 is better than coax because:
?
The twisted pairs are naturally balanced and according to him, less prone to common mode problems
The characteristic impedance is 100 ohms
The multiple twisted pairs offer 4 different possibilities of use. i.e. power for the pre-amp, antenna lead(s), T/R protection switch, etc.
?
I am seriously looking at this antenna for 160 meters as I have a small lot and cannot use a proper 160 meter receive antenna.
?
73
Warren / NI5L
?
|
Hi Warren!
Don't really know. But why not try and find out?
/Hans
Hans,
?
Would there be any problem feeding the antenna and pre-amp with CAT-6 cable?
?
I read an article by a Canadian fellow that CAT 6 is better than coax because:
?
The twisted pairs are naturally balanced and according to him, less prone to common mode problems
The characteristic impedance is 100 ohms
The multiple twisted pairs offer 4 different possibilities of use. i.e. power for the pre-amp, antenna lead(s), T/R protection switch, etc.
?
I am seriously looking at this antenna for 160 meters as I have a small lot and cannot use a proper 160 meter receive antenna.
?
73
Warren / NI5L
?
|
That's exactly what I intend to do.? :)
?
73
|
On Tue, Feb 11, 2025 at 04:17 PM, Warren Dean / NI5L wrote:
Would there be any problem feeding the antenna and pre-amp with CAT-6 cable?
No, there would be no problem, this a a proven technique. Te original LZ1AQ AAA-1C? active loop is using twisted pair Ethernet cable as feedline, power supply line and control line..
?
"Ethernet cables are designed to handle frequencies that coincide nicely with most of the interesting amateur radio bands, and their insertion losses not much worse than RG58. The twisted pairs are also a balanced system that’s good at rejecting common mode noise. Cat 6 cable also has four pairs of conductors, allowing you to feed multiple antennas with one cable, or to distribute power to amplifiers and switches along with antenna feeds."
?
Video:
?
?
regards, Fred
|
Thanks for that, Fred. I am definitely going to use CAT6 for the loop. We shall see how it works out.
?
73
Warren / NI5L
|
Hi Fred, Thanks! I wonder what difference will UTP vs S/FTP make? I use S/FTP cat8 (24awg) patch cable for my LZ1AQ (original AAA-1). I know that at antenna side cable shield is not connected to common GND to keep line symmetrical (relative to GND) and for less CM issues. Same should be applied for other antennas if shielded CAT is used (shield not connected on one side, most likely antenna side)... Regards, Simon On Tue, Feb 11, 2025 at 9:57?PM Fred M via groups.io <dl4zao@...> wrote:
On Tue, Feb 11, 2025 at 04:17 PM, Warren Dean / NI5L wrote:
Would there be any problem feeding the antenna and pre-amp with CAT-6 cable?
No, there would be no problem, this a a proven technique. Te original LZ1AQ AAA-1C active loop is using twisted pair Ethernet cable as feedline, power supply line and control line..
"Ethernet cables are designed to handle frequencies that coincide nicely with most of the interesting amateur radio bands, and their insertion losses not much worse than RG58. The twisted pairs are also a balanced system that’s good at rejecting common mode noise. Cat 6 cable also has four pairs of conductors, allowing you to feed multiple antennas with one cable, or to distribute power to amplifiers and switches along with antenna feeds."
Video:
regards, Fred
|
What about this diamond shape antenna, would it better? I have a Wellbrook FLG100 Wellbrok module amplifier. I dont know if the growning flag will be better.
?
?
https://swling.com/blog/tag/small-unidirectional-loop-antenna-sula/
?
https://swling.net/viewtopic.php?t=55
|
The SULA is a smaller loop than most FLAG antennas but both bigger than a YouLoop
?
Regardless they are interesting to experiment with and can use a preamplifier
?
The County Wireless loop amp is a great one to use, low noise floor
?
John VE3IPS?
|
The shape isn't critical. Att that matters is loop area (length x height). Bigger area, more gain.
?
/Hans
|
I did something similar in 2008. One design was a small bidirectional loop on a rotor, and the other was a four-turn spiral loop on a rotor. Both used Wellbrook ALA100 modules. Support elements in one case was fiberglass fishing poles, and fiberglass tent poles for the other:
?
?
?
73,
?
Guy
|
Oops, this 3rd link is the one for photos of the spiral loop on rotor:
?
?
-Guy
|
Hi Guy,
why did you choose a spiral-loop?
The enclosed loop area is a key figure of merit of a small magnetic broadband loop. With a spiral loop the enclosed loop area decreases with each winding.
?
regards
Fred
|
Hi Fred,
?
If I recall, it was an experiment I tried after reading about *tuned* spiral loops (windings in the same plane) in the early days of radio. My intented use was MW only, and I was seeking a greater amount of wire in the same space, and hoped this would work for a broadband loop also, vs. tuned. Indeed, it never worked as well as my single turn version, although it still had some good nulling ability on MW.
?
Guy
|
Hans Ostnell
Warren Dean / NI5L
John
Guy Atkins