3el Cubical Quad, HPSD 4,21 meter


The strongest signal produced from Northern Australia is from 43TR299 the 3 element above is the reason why.
(tnx geoff for using pics) homesite 43TR299

Below you can find the dimensions for a 3el Cubical Quad.
The antenna has a total boom length of 4,21 Meters and produces a 9,5dBi gain
which is incredible for such a relative small boom length.
The impedance of the antenna is 50 ohms.
The antenna can be direct fed, a 1:1 balun is of course always recommended
The wire diameter is 2,5 mm bare copper wire. Do not use any other wire diameter.
If you use insulated wire you need to shorten the element length with approximately 2/3 percent.

Questions? Or If you do need for example dimensions with other diameters…please do mail.

Below the azimuth plot :

Below the elevation plot:


Below the predicted SWR behaviour:

Boom length 4,21m HPSD 3Q
Design freq:
27,555 MHz
9,5 dBi
24,03 dB
Beam width:
Band width
550 kHz
A (director) =
B (radiator) =
11.166 mm
C (reflector) =
11.541 mm
D (dist ref-rad) =
2107 mm
E (dist rad-dir)=
2103 mm