Building antenna

[Durango-Kid]

I don't understand how to hook up a coax cable to a antenna. I have an old ST3 and the center coax hooks to the vertical element while the horizontal elements hook up to the sheath in the coax which also hooks up to the mast ground. So, my question is why aren't all of the elements hooked to the center wire?

I am trying to build the ST2 antenna and trying to figure out the correct wiring to the elements. Do I need to use the 300 to 75ohm balun or can I hook it up direct? I am just trying to receive on my scanner.

 

[dlwtrunked]

I don't understand how to hook up a coax cable to a antenna. I have an old ST3 and the center coax hooks to the vertical element while the horizontal elements hook up to the sheath in the coax which also hooks up to the mast ground. So, my question is why aren't all of the elements hooked to the center wire?
...

Not trying to be a smart aleck, but why would they be. Think of this in a crude way: When ever there is an electric potential (voltage) in electronic circuits, it is between two conductors ("wires"). In an antenna, electromagnetic energy ( radio waves), need to generator a voltage. It has to be between two conductors ("elements"). And that voltage has to go to the receiver via two conductors (center wire and shield). Although this was said in a greatly simplified crude way and some antennas are more complicated, it is the basic idea. It is true that if you connected all the elements to the center, it will still act like an antenna to some extent (but poorly) as the shield itself and whatever it may be connect too will act as the other element of the pair of conductors in which RF is generating voltage.

 

[Ubbe]

Your antenna is a ground plane antenna. The vertical element is the receiving part and the horisontals are the ground plane that acts as impedance and direction aids and are fine to ground to the mast together with the coax shield.

You can try and connect the 300-75 ohm balun as it should help to expand the frequency range of the antenna. If possible do a before-after test.

/Ubbe

 

[Durango-Kid]

Thanks guys. That gives me a better idea of what I am doing.