70 cm Vertical Ground Plane Radial Omni-Directional Antenna

grabcad

This is a model of a low-cost 70 cm Vertical Ground Plane Radial Omni-Directional Antenna that uses a 3D printed arm to support all components about a foot away from the mast. This antenna can be made longer to support many other VHF or UHF frequencies up to 1 GHz and down to FM radio 88 MHz. https://en.wikipedia.org/wiki/Whip_antenna#Ground_plane_antennaThis type of antenna is useful for mounting on the side of the mast since larger yagi beam antennas prefer to be at the top of the mast for rotation.This antenna is simple enough to be used for many other bands such as :* ISM 900 MHz* Marine VHF* Police Scanners* 2m Amateur Radio* 6m Amateur Radio* Aviation Radio* and many others !Tuning for the radiator is 1/2 wavelength and each counterpoise ground radial is 1/4 wavelength. Lengths should be made longer for lower frequencies and then trimmed to raise the frequency to the center of the band of interest. An antenna analyzer or VNA helps here.Here's a calculator :https://m0ukd.com/calculators/quarter-wave-ground-plane-antenna-calculator/The angle of the radiation pattern is related to the angle of the ground radials. To lower the radiation pattern bend the ground radials down and to raise the radiation pattern, bend the ground radials up. - - - Also bear in mind that bending the ground radials *down* will 'raise the impedance' of the antenna (straight down approaches that of a dipole ~ 73 ohms) and that bending the radials *up* will 'lower the impedance' of the antenna (a flat ground plane is ~ 22 ohms).The list of materials is simply :* hobby 3.5 mm brass tubing (K&S) :https://ksmetals.com/products/br225mm-3hbut can be aluminum instead as 4 mm aluminum tubing (K&S) :https://ksmetals.com/collections/aluminum/products/al45mm1m-4* (4) 2.9mm self-taping screws 9.5mm long (ISO 15481)* (1) N-Type connector - preferably right angle or with a right angle adapter (AMP 8975 shown).* (1) 10 AWG solid copper wire slug to bridge the tubing of the radiator to the N-connector* (5) 3.5mm tubing end caps :https://store.mocap.com/mocap_en/rvc.html?Item=RVCC9007-5&Inside_Diameter=0.13700&Length=0.500&Material=BLACK* (1) 3D printed arm supportDuring construction the counterpoise ground radials will need to be flattened to fill the channel and have good contact against the N-type connector. They should probably be soldered in place for better conductivity since antennas tend to vibrate in heavy winds.Silicon sealant should be used ins...