In a USB key that was laying since years in a drawer,I found some old pictures of both the design and the construction of the antenna that I described in the article: Quagi 8 elements 432MHz. I though to publish some of them, may be because some are weird, maybe because some are useful and might help or to other U/VHF antenna homemakers.
Hope you'll aprreciate my effort...
In the 80's, when I was 12-13 years old, I used to be a CBer, with a little legal transceiver by CTE International, model SSB 350, and a "Skylab" antenna. I remember that such antenna was advertised as an outstanding gain one, up to 7 dBi, or something like that. Today, I took the opportunity to verify with NEC2 if the gain of a Skylab is actually so good. Here you are the outcome of my investigation...
Well, the gain is that of
Would you like to build a simple antenna for 70 MHz band? I sized "on the fly" this 4 elements Quagi for 4 meter band, but I did not make any prototypes, yet; anybody wants to make one?
Use aluminum pipe, diameter 10mm x 1mm thickness. You find it in DIY shops in 2 meters long pieces, or in non-ferrous metals storesin 4 meters long pieces (yeah but, how are you then going to carry it to your home?) so you'll need to make at least one or two joints.
In order to make sharp corners for the loop elements, because bending the aluminum pipe with small curvature is not that easy, I kept into account a curvature radius of 30mm (three times the tube diameter). However, if you can get even a sharper corner, that's good for your antenna!
The antenna boom must be made of wood or other non-conductive material (the boom is not shown in the pictures because, beeing insulating, it's not needed in the simulation model).
Feed your antenna in the middle of an horizzontal side of the "Driven Element" (the one
I tried N6NB's project but it didn't work well. Actually, there were some differences from the original project: for the Driven Element and the reflector, I used 1.8mm solid copper wire (the one for coils or transformers) because, at least in Italy, the old insulated #12 TW solid copper wire is too hard to be found. Furthermore, the Directors diameter was 4mm instead of 3mm. Probably these differences resulted in unacceptable Standing Wave Ratio, as you can see here below:
Fig. 1 Experimental SWR curve obtained with N6NB's design (materials as specified in the text above)
Someone suggested me to optimize the antenna through NEC2, and... here you are the first results.
This Quagi is optimized for