This 2 element delta loop beam for the 10m band is really easy to build, small enough to be packed up in a back pack and used out portable for POTA or setup at the home QTH and used for chasing the DX.
For such a small antenna it has a great F/B ratio and plenty of forward gain.
The driven element of the antenna is very slightly smaller than the reflector element and caution should be taken when measuring the wire lengths for each element to ensure accuracy.
The peak of the two elements is the same at 3m above ground with the two horizontal wires of each element being exactly 1m above ground. This 1m above ground measurement is important as raising it above this level will increase the angle of maximum radiation.
As shown by the 3D far field plot the radiation pattern shows an excellent F/B ratio of 20.41dB and a forward gain of 10.14dBi at 10 degrees elevation. For such a small, simple antenna these are very good figures.
The antenna presents just under 100 Ohms impedance at the feed point (denoted by the red circle at the end of wire 1 on the driven element shown in the antenna view above) and will require a 2:1 Balun at the feed point to match perfectly to 50 Ohm coax.
The antenna presents a very useable SWR curve between 28Mhz and 29Mhz.
To make the 2:1 Balun I suggest a 240-43 mix Ferrite Toroid with windings as shown below. This is real simple to make and should be housed in a water proof box capable of taking the strain of the wires being pulled tight to form a triangle.
Since the feed point is at the bottom corner of the driven element the balun box could easily be supported by a non-conductive post at the correct position.
Summary:
Driven Element
Horizontal Wire Length: 5m @ 1m above ground
Diagonal Wire Lengths: 3.20m
Height at Centre: 3m
Wire Dia: 2.5mm
Feed Type: 2:1 Balun in bottom corner
Impedance: 50 Ohm
SWR: <2:1
Reflector Element
Horizontal Wire Length: 5.1m @ 1m above ground
Diagonal Wire Lengths: 3.24m
Wire Dia: 2.5mm
Height at Centre: 3m
Distance between Elements: 2m
Gain: 10.14dBi at 10 Degrees
F/B: 20.41dB