New VHF antenna (5-element yagi)

I decided to use the full available length of the 2-metre wooden boom to build a 5-element yagi. Having played a bit with 4nec2 I ended up with the following design:

	Distance from Reflector [mm]	Length [mm]
Reflector	0	1020
Folded dipole	326	990 (adjust to match)
Director 1	628	940
Director 2	1143	910
Director 3	1909	880

This time the fed element is a folded dipole with 0.5λ transmission line balun (68.5 cm of RG-58 coax). The length of the arms of the folded dipole can be adjusted so that optimum matching is achieved. As you can see on the picture below, the antenna impedance measurement results are rewarding:



The antenna has a relatively flat resonance around 144.250 MHz, with SWR not exceeding 1.1 at 0.5 MHz bandwidth. Unfortunately, it's very difficult to measure the radiation pattern inside the appartment. However, the received beacon signal strength is at least as good as on the previous 4-element antenna. Actual performance will be estimated later, during QSOs on 144 MHz.