Apartment Base Scanner Antenna help

[FCVPI99]

so im going to be putting an ant in the attic (i cant put one outside) but im not sure what way to go .. or even if i have a choice as i dont not anything really about diapoles
now do i ....
pic put a discone up there (thinking i will have a dead spot in coverage due to chimney blocking that direction)
pic 2 use a like 50 foot end to end Diapole and run alone the peak OR run in the shape of the L so 1 leg pics up N and S and other leg picks up E and W maybe?
or
Pic 3 use a like 200 foot end to end diapole and wrap it around the roof line about half way up the roof (thinking it will pick up from all directions)

its a brick chimney that is right in the center

 

[rf_patriot200]

so im going to be putting an ant in the attic (i cant put one outside) but im not sure what way to go .. or even if i have a choice as i dont not anything really about diapoles
now do i ....
pic put a discone up there (thinking i will have a dead spot in coverage due to chimney blocking that direction)
pic 2 use a like 50 foot end to end Diapole and run alone the peak OR run in the shape of the L so 1 leg pics up N and S and other leg picks up E and W maybe?
or
Pic 3 use a like 200 foot end to end diapole and wrap it around the roof line about half way up the roof (thinking it will pick up from all directions)

its a brick chimney that is right in the center

Why 200 feet ?? If you'll be listening on your scanner, that's way too long. Go with the discone, and RG6 Quad shield cable. You'll hear much more.

 

[prcguy]

Why 200 feet ?? If you'll be listening on your scanner, that's way too long. Go with the discone, and RG6 Quad shield cable. You'll hear much more.

Why recommend 75 ohm cable for a 50 ohm antenna? Why quad shield over single shield?

 

[hazrat8990]

What frequency range are you planning on monitoring? Reason I ask is that a dipole for VHF is around 38 inches total, not 50 feet!

 

[rf_patriot200]

Why recommend 75 ohm cable for a 50 ohm antenna? Why quad shield over single shield?

Quad shield cable helps to get more received signal from your antenna to your scanner, and the 75 ohm impedance is not a concern as long as you're not transmitting. RG6 Quad shield is designed for Vhf/Uhf signals, hence the reason it works so well for tv signals.

 

[prcguy]

Quad shield cable helps to get more received signal from your antenna to your scanner, and the 75 ohm impedance is not a concern as long as you're not transmitting. RG6 Quad shield is designed for Vhf/Uhf signals, hence the reason it works so well for tv signals.

No. Quad shield has the same loss spec as single shield (of the same brand/series) and any loss you incur on transmit from the 50/75 ohm mismatch is exactly the same on receive. It’s signal loss. Quad shield is intended for satellite downlinks in the 950-2150MHz range where cables can be tightly bundled together and at L-band you can have some cross talk between cables. At lower frequencies like we use for scanning there is no benefit from using quad shield. Except the hassle of special connectors and extra labor installing them if you like doing more work.

 

[rf_patriot200]

No. Quad shield has the same loss spec as single shield (of the same brand/series) and any loss you incur on transmit from the 50/75 ohm mismatch is exactly the same on receive. It’s signal loss. Quad shield is intended for satellite downlinks in the 950-2150MHz range where cables can be tightly bundled together and at L-band you can have some cross talk between cables. At lower frequencies like we use for scanning there is no benefit from using quad shield. Except the hassle of special connectors and extra labor installing them if you like doing more work.

I see. For some reason, I've had better luck with more shielding on everything from vhf to 1296mhz.

 

[FCVPI99]

so the dis-cone ant being next to a chimney wont give it a dead spot? ... being i cant get over it i fig encircle it that way no dead spots