Question Re: Horizontal Loop Antenna

[ridgescan]

Now that I'm stuck at home like everyone and everything else, I'm considering converting my 100' L-shaped endfed wire to a horizontal loop (this loop will be huge.) My question is, will the fact that my Wellbrook loop and my D130J discone antennas will be in the center of this new horizontal loop have any negative effect on its performance?

 

[prcguy]

Probably not. I assume you would run it around the perimeter of your building? I think the close proximity to the roof and railing and everything else will skew the loops performance more than some smaller things in the middle.

Now that I'm stuck at home like everyone and everything else, I'm considering converting my 100' L-shaped endfed wire to a horizontal loop (this loop will be huge.) My question is, will the fact that my Wellbrook loop and my D130J discone antennas will be in the center of this new horizontal loop have any negative effect on its performance?

 

[ridgescan]

Probably not. I assume you would run it around the perimeter of your building? I think the close proximity to the roof and railing and everything else will skew the loops performance more than some smaller things in the middle.

Thanks prcguy

 

[ridgescan]

I spent all day deploying a horizontal, 180' wire loop. I'm using the PAR 9:1 trans. One end of the loop connects to the antenna stud; the other end connects to ground stud #2; and ground stud #1 is RF-grounded to the building. I done did it prcguy
Goes around the perimeter of the roof, 7' high, held by four wood masts with floating standoffs.
Cannot wait until evening to try it out!
prcguy, thank you much for suggesting I try this loop. We will see how she goes.

 

[popnokick]

Horizontal "mag" loops can work very well. One of our ham club members designed one a couple years ago for an event we did in conjunction with an excursion railroad line. We operated from the caboose of the train. The horizontal loop was designed with EZ-NEC and had adjustable tap / feed points for 20 and 40 meters. We mounted it about 7 ft above a railroad flatcar using a 2x4 at each corner of the flatcar. Worked very well for "railroad mobile" in motion.... ran two HF stations on it. CAUTION: Horizontal mag loops develop very high voltages when transmitting. Stay away from the antenna elements when transmitting!

 

[ridgescan]

Lucky I just receive here PK Just getting into how this thing's behaving. More noise than the old wire around 40 meters, about the same in 30 meters too. But what I like is there is far, far less noise 20 meters and up, 80, 160 meters. Way less noise in LW. Time to pour a cup and check MW now that MWDX is settling in.

 

[ridgescan]

After a couple days of testing it turns out the loop wasn't the greatest. The spots in HF where I said it was a lot quieter, it was actually deaf. Maybe using the PAR 9:1 trans was the culprit, or the way the 180' wire is configured I don't know. So I snipped off 10' of the loop from the ground connection and tied it off on the final mast, so I now basically have a 170' perimeter-configured endfed wire. I basically now have two wire broadsides north/south and east/west.
And it works a LOT better. All bands. MW now has much bigger signals too. As I type I have VOA on 5925kHz from Selebi-Phikwe, Madagascar with absolutely reliable voice and +15-+20 over on the R75 meter. With the 100' lazy-L wire they were good copy but only 7-9 s-units.
Hey ya gotta try right? A never ending pursuit of God knows what.

 

[WA8ZTZ]

Ridge,
Maybe, just for kicks, give that loop another try but without the balun this time.
You are going from a balanced loop to unbalanced coax but the mismatch in a receive only application
is usually not a big concern.
Full wave loop impedance at resonance (in your case 5580 kc, as f= 1005/L with F in mc and L in ft) in free space is about 100 ohms.
So, with a 50 ohm input on the R-75, your mismatch is 2:1. A 2:1 mismatch on a receiver is really not that big of a deal.
This will, of course, change at different frequencies. So, if impedance matching is desired, then use an antenna tuner (transmatch).
In your urban environment, if front end overload becomes an issue, then a preselector may be useful.
Just some thoughts off the top of my head that you may want to consider.

 

[ridgescan]

Ridge,
Maybe, just for kicks, give that loop another try but without the balun this time.
You are going from a balanced loop to unbalanced coax but the mismatch in a receive only application
is usually not a big concern.
Full wave loop impedance at resonance (in your case 5580 kc, as f= 1005/L with F in mc and L in ft) in free space is about 100 ohms.
So, with a 50 ohm input on the R-75, your mismatch is 2:1. A 2:1 mismatch on a receiver is really not that big of a deal.
This will, of course, change at different frequencies. So, if impedance matching is desired, then use an antenna tuner (transmatch).
In your urban environment, if front end overload becomes an issue, then a preselector may be useful.
Just some thoughts off the top of my head that you may want to consider.

Thanks for the input! I'm going to stick with this setup for a little bit though-I love the way it's performing so far.

 

[WA8ZTZ]

As they say... if it works, don't fix it.

 

[ridgescan]

As they say... if it works, don't fix it.

Absolutely but I agree with your estimation regarding that trans. I bet if I just do a direct coax hookup it'd be what it's supposed to be.