*Homemade Quad* by 3DA012 Roger

I’d read and heard so much about this antenna over a period of 3 years that I finally decided to build one.  I wasn’t disappointed with the result either!

The first quad antenna I ever built had a 5.7m aluminium boom with 4 bamboo elements.  It was working fine too but due to the climatic conditions here in Brazil (ie. the warmth and humidity) the bamboo pieces wrotted quickly and had to be changed after just 6 months of use.

During my recent travels to Europe, where I had the pleasure of catching up with a number of DA-RC mates, I brang 16 x telescopic 4m fiberglass fishing rods back to my home QTH to use instead of the bamboo.  These cost just 5 euros in a sports supermarket.

Some adjustments where made to the antenna in order improve the performance and I decided also to build it using simple materials.

4 Element Quad Size

Antenna size: 

  • The boom is 5.7m long.  It’s an aluminium 5cm diameter can and that’s a good size for a 4 element in my opinion.  The arms size are 15cm longer than needed so some frequency changes can be done on the antenna if this is desired.
  • Reflector arm  303cm
  • Radiator arm  299 cm
  • 1st director (next to the radiator one) 289cm
  • 2nd director (last one on boom)  278cm

The wire elements size are:

  • Reflector: 11.52m x 1.5mm copper wire (stranded).  It’s a little big longer than on my first quad and it provides less back ratio (7cm).
  • Radiator: 11.1m x 1.5 rigid copper wire
  • 1st Director: 10.96m x 1.5 stranded copper wire, 16cm more thhj an on my first quad
  • 2nd  director: 10.54m x 1.5 stranded copper wire, 8cm more than with my first project

Spacings:

  • The spacing between the reflector and director is 203cm
  • Between the radiator and director  167.5cm
  • Between the 1st and 2 director 167.5cm

[IMPORTANT NOTE: YOU MUST LET YOUR COPPER WIRE BE “NAKED”.  TAKE THE ISOLATOR OFF!  If you don’t do it then your antenna will work about 1 or 2 MHZ lower on frequency].

Notes:

I made a mixture of rigid and stranded wire because stranded wire is easier to use in my opinion and I don’t think it makes a big difference at all.  I put varnish paint on it to avoid oxidation and used rigid copper wire for the radiator which is the part that receives the TX power.  I used it with a 350w power amplifier and it didn’t take fire until now lol.

Even if I have 50 OHMS on the antenna, I still use a 1/1 Balun to be sure that the antenna works fine.

Last but not least, the antenna take off angle from the ground was about 15° > at 12m high and the antenna was used in a diamond pattern but can be used in square pattern also, changing the radiator feeding point without any performance changes.

The antenna ready, the ROS- TOS is 1.5 at 27.100 Mhz and 27.800 MHz with 1.1 from 27.335 to 27.580 MHz.  That makes about 700 Khz band width and that’s less than on my first quad project where I had 1.2 MHz bandwith.

Testing

My first test on the air with the new quad was on June 2 with some European propagation and 6 activations in the log with 310DX/LI a new DXCC among them.  The antenna appeared to have been created well and no changes were needed.

The next test was done during the WWRO Festival weekend and gave me 53 stations in the log.  So definitively it’s a fine antenna working perfect with low propagation and on weak radio transmission!

Outside all that is written about the difference between yagis and quads, I find another difference is that you are hearing conditions before and after a yagi antenna has closed down.

Putting it together with a Yaesu FT-950 transciever and you have a letal DX weapon.  What you are able to hear you can contact!

PS. About the construction, I have made it very simple so everybody can build this antenna without too much difficulty.  But it also can be upgraded depending on each person’s  capacity.
This antenna has been up in the air for 3 months without any damage or problems.