14MHz Delta Loop Construction (version of M0PLK)

Used parts:

• aluminium plate thickness 4mm 250x250mm
• aluminium tubing: 25x2mm; 21×1,5mm; 16x1mm 2 pieces each – 2m length
• U-bolt M8 x4 + washers + nuts – base plate tubing mount
• U-bolt M6 x2 + washers + nuts + mounting brackets x4 – base plate to mast mount
• wire PE isolated 1,5mm2 – antenna wire
• center isolator
• ladder line spacers – pieces of IKEA racks
• 2x M12 bolts + washers + nuts – tubing connection with wire
• hose clamps for tubing – 2 pieces for each tubing piece

Tubing mounted to the base plate using M8 U-bolts. The tubing is electrically connected to each other by short 3mm2 PE isolated jumper. (Whole tubing piece touching the base plate is isolated by 2 layers of the heat shrink)

Jumper is connected to the tubing with M6 bolts and eye-connectors.

Center isolator holes for electrical connection are spaced 6,5cm. Holes for holding wire tension are spaced about 8cm. Ladder line and wire connected with M6 bolts and eye – connectors. Wire before connection is looped by outer holes and clamped with the steel rope clamp, to prevent connectors from wire slip out.

In the end of 16mm tubing M12 bolts are inserted and clamped with the hose clamp. Wire is looped by the bolt and clamped with the steel rope clamp and then connected with an eye – connector between washers and M12 nut. Looping prevents wire from slip – out. Placing eye-connector between washers and bolt nut makes electrical connection safe for longer time – CU is not touching aluminium.

The base plate is mounted to the mast with M6 U-bolts.

The antenna finally mounted on the tarrace – bottom of the antenna is about 12 m agl. SWR on 20m band in the feed point with 7m coax choke – 1,3:1. In the future I want to put up some kind of telescopic mast in the place of crap one.

03.09.2018 UPDATE:

Having bought all needed parts, I decided to make serious 1:1 balun instead of the choke in the feed point. To make the balun I used FT-140-43 core winded with 1mm2 enamelled copper wire – 10 bifilar windings with an interlace after 5th winding. Measurements of the balun with a dummy load:

• 7-21MHz 1,1:1 SWR
• above 21MHz rising SWR – 28 MHz 2,2:1

Measurements of the antenna + balun at the feed point (VNA):

• It’s not a traditional M0PLK so it is not a multiband antenna. It was redesigned to resonate and get the highest performance on 20-meter band.

Conclusion: The constructed antenna is a very nice antenna on 14Mhz and 24MHz bands. It is very, very quiet in comparison to a dipole antenna – the background noise level is about 3S lower than on the dipole antenna.

I made some dx on 20m band with the antenna. The antenna cost me about 50$ here in Poland.

I did not see any directivity in the antenna radiation pattern. I have rotated it a few times, but I did not discover any difference. I truly recommend this antenna for beginners, it is very easy to put up and has some serious potential for making some first dx.

The biggest con is the lack of multiband capability – the antenna can be easily tuned in the shack with MFJ antenna tuner – honestly saying not only the antenna but coax also…

SPRING 2019 UPDATE:

Mast replacement for telescopic one + some antenna improvements like fixed balun position.

Wind resistance:

SPRING 2022 UPDATE:

Tubes isolation at the base plate has failed – double shrink tube turns out to be not enough reliable and weather-resistant. During the last 3 years, I had to replace them already twice. Finally, I decided to replan the tube mounting solution at the base plate. Heavy-duty hydraulic hose brackets have been chosen for a new arrangement. Now the whole construction looks more professional and reliable. I used three brackets for each tube to ensure the stability and reliability of the base plate.