The AM Forum
November 05, 2024, 03:58:35 AM *
Welcome, Guest. Please login or register.

Login with username, password and session length
 
   Home   Help Calendar Links Staff List Gallery Login Register  
Pages: [1]   Go Down
  Print  
Author Topic: 10 Meter Rectangular Loop  (Read 50198 times)
0 Members and 1 Guest are viewing this topic.
Steve - K4HX
Guest
« on: February 02, 2012, 10:42:16 PM »

Here is a very simple wire antenna you can build for 10 meters and quickly get in on the AM action now that the sunspots have returned. It is nothing more than a rectangular full-wave loop that has a 2:1 height-to-width ratio. It is fed at the bottom-middle of the loop and the feedpoint impedance is 50 Ohms.




The dimensions above are for uninsulated wire and will produce resonance at the lower end of the 10 meter band. I built a loop using 36 feet of #12 insulated wire and had to trim 8-10 inches to obtain resonance at around 28.8 MHz (better for AM operation above 29 MHz). If I had to do it over, I would have made the loop 35 feet in total length and put a 6 inch stub with a shorting bar at the top of the loop (opposite the feedpoint). Sliding the shorting bar would allow for setting the center frequency almost anywhere in the band quickly and easily.




The antenna can be put aloft with just one support. I used a rope and PVC horizontal spreaders/spacers (as shown in the photo above) or you could mast mount the loop (as shown in the drawing below). PVC pipe can be used as spreaders or support arms.




The loop has 1-2 dB more gain than a horizontal dipole and 8 db gain over a vertical dipole (or most other verticals). It still has broad lobes like a dipole, so geographic coverage is good. If mast mounted, a rotor could be used. I turn mine (tree mounted) with a rope.

Loop Versus Horizontal Dipole (loop pattern in Red)


Azimuth



Elevation


Loop Versus Vertical Dipole (loop pattern in Red)


Azimuth



Elevation


Make sure you use a balun at the feedpoint. Several turns of coax in an 8 inch loop will work fine or you can use a bead or toroid balun.

If you want to get on 10 meters and join in the fun, try this rectangular loop. You can build it and have it up and on the air in an afternoon.

Catch you on 10!
Logged
KA3VID
Contributing
Member
*
Offline Offline

Posts: 50


« Reply #1 on: November 03, 2021, 09:25:56 PM »

Since it's all I have on hand would 450 ohm ladderline work with this antenna, or do you only recommend using coax ?
Logged
Steve - K4HX
Administrator
Member

Offline Offline

Posts: 2734



« Reply #2 on: December 24, 2021, 01:14:13 PM »

If you have a tuner with a balun or a balanced tuner, you should be good.
Logged
km6sn
Contributing
Member
*
Offline Offline

Posts: 91


« Reply #3 on: December 30, 2021, 05:03:31 AM »

Allison, KB1GMX, claims that with 5 watts (I assume SSB) into this antenna
you can work anything you can hear.
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
 AMfone © 2001-2015
Powered by SMF 1.1.21 | SMF © 2015, Simple Machines
Page created in 0.048 seconds with 18 queries.