The cubical quad antenna is without doubt one of the best DX antennas currently available and is a proven performer! One of the greatest advantages of the quad is that it exhibits a lower angle of radiation than a Yagi at heights of less than one wavelength. This makes it a great antenna for working long distances as more of the power is radiated at low angles even if you can't get them mounted as high as you would like.
One of the reasons for the effectiveness of the quad antenna is the fact that it not only exhibits more forward gain and a very good front to back ratio but also it has a larger physical capture area than a Yagi of the same boom length. Each element is a full wavelength in size compared to a Yagi which has elements of only one half wavelength making the quad a far more effective antenna for both TX and RX.
As with any antenna the true performance is only achieved when all elements are resonant at their correct frequencies and also when the feed point is matched correctly and the antenna is installed as high as possible from the ground or the roof.
The original article dated the 1 May 2023 is available HERE
When I constructed this light weight quad antenna I only had a SWR Meter on hand. I bought a NanoVNA about a year ago but never got to measuring any of my antennas. Well I found some time and this is the results that the NanoVNA provided. I am more than happy with this antenna and its performance. It is a great asset to my VHF/UHF Antenna Arsenal.
(Click on images for larger view.)
Looking at the Impedance of this antenna the following readings are provided by the NanoVNA:
64 Ohm at 144.000 Mhz
59 Ohm at 145.000 Mhz
57 Ohm at 146.000 Mhz
To get it closer to 50 Ohm I can play around with the length of the 75 Ohm Matching Stub. However the above readings is more than good enough for me.
