6 meter Squalo antenna Horizontal polarized Omni directional

6 meter Squalo antenna Horizontal polarized Omni directional Used for monitoring to complement directional antenna It’s a dipole folded into a square

6 meter Squalo made from 5/8 inch aluminum 28 inch per side 12 inch Gamma match PVC support SO 239 Connector Tuning stub made from 400 Ohm ladder line

Gamma match detail Gimmick capacitor using RG-8 center conductor inserted in gamma match tube (Sealed with silicone) SO 239 Connector

Rough tune in garage by trimming stub length VSWR=2

Designing the RF choke (balun) • #31 and #43 ferrites (2. 4 inch diameter) on hand #31 has better broadband characteristics • Measuring chokes at VHF is challenging • Goal is to rough out a reasonable feedline choke using as few cores as possible for light weight

1 T RG-58 thru three #31 cores: 210 Ohms

2 T RG-58 thru three #31 cores: 860 Ohms

3 T RG-58 thru three #31 cores: 2100 Ohms

2 T RG-8 thru three #31 cores: 1400 Ohms Increased stray capacitance of RG-8 moves resonance too low. Large loop minimizes capacitance.

Balun conclusion • Much better performance using RG-58 due to minimum stray capacitance(>2000 Ohm choking impedance for 3 T) • RG-8 is desired for loss and power handling • 2 T of large RG-8 loops gives >1000 Ohms choking impedance • This will be fine for a general purpose (mediocre performance) antenna

Antenna mounted at 30 feet 600 k. Hz bandwidth VSWR=2 bandwidth (measured thru 100 ft of RG-8) VSWR=2

Conclusions • Power test- 500 W for 60 seconds: No arcing, stub does not melt • Very useful addition to antenna arsenal • About 6 -10 d. B down from STEPPIR with 6 meter element at 55 feet • 15 TO 25 d. B better for signals to the side or back of STEPPIR • Use when STEPPIR is on another band