Antenna Range

[maddogdecker]

I was wondering about how high I should go on an outdoor antenna. Or what is the best range hight? I have always heard between 20ft to 30ft up. I have one know but it is only about 12ft high. It does pretty good.

 

[RevGary]

Need more info - What bands are you monitoring and with which model of scanner as your primary, how far is the most distant transmitter that you might wish to monitor during mid day ( when background noise is the highest ), which antenna or antennas are you using or considering, what type of cable are you using or considering and are there any close proximity obstructions such as trees or high buildings? Give us the parameters under which you wish to operate so we can give you some specific info and suggestions...

 

[maddogdecker]

I"m just wanting to use maybe the pro 2096 or the pro 2055 that is up in the air right now. I'm wanting to pick up 800mhz system & VHF High frequencys. I would like to be able to pick up maybe 20 to 25 miles. I'm using all Radio Shack stuff. I really can't afford much else. I already have Outdoor VHF-Hi/UHF Scanner Antenna/Model: 20-176. It's already outside at 12ft high. I'm looking into the ham antenna that radio shack has. That is all I can remember about it, it is currently not on there website. The closest obstructions that maybe a problem would be woods which I would say are maybe 500 yards away. There are no tall builds close by to where I live. I live close to a State Road. Hope this helps. I told you all that I thought would help. Need anything else let me know I will do the best to answer them.

 

[LarrySC]

The 176 only has a capture area of appx 18" + 6" + 6" = 30". Measure the length of each element on a Scantenna and add them up. Compair to the 176. As you can see the Scantenna will capture almost 10 times as much signal. You can get a 5db gain 800 mHz base antenna also. Look at www.bncantenna.com for ideas.

 

[RevGary]

Hi again, Steve - The 20-176 antenna is a good multi band antenna if you are on a budget and it should do what you want it to do. It is rated at 108 to 1300 Mhz.

If you have room, pick up 3 of the Radio Shack 10 foot 16 gauge mast pipes # 15-863 and one house gable bracket # 15-886 as well as some 1/8 inch guy wire. Depending upon your residential configuration, this will get the tip of your antenna about 34 feet off the ground. This will increase your reception distance by roughly 40 to 50%, although there are some variables. The bottom mast pipe can be slipped over a smaller diameter 6 to 8 foot section of galvanized steel water pipe driven into the ground and left above ground by 12 inches. This will prevent the bottom mast from 'kicking out' in wind. Drill a 3/8 inch hole through the mast 6 inches off the ground - all the way through the steel pipe inside and out the other side of the mast. Use a 2 1/2 inch bolt, lockwasher and nut to secure the mast to the inner water pipe. This will also effectively ground the mast. Sounds like you may have to get a new piece of cable, so one of the common one's with low loss is RG8 which is 3/8 of an inch in diameter - much easier to work with than the larger cousin RG8/U. You will probably get other suggestions, but some Radio Shack stores have the RG8 on closeout and it is very reasonable. I recently picked up a 105 foot remnant for less than $20.00. Lightning protection for the CABLE itself is another matter. You may have to check with someone in your local electrical inspection department to see what the grounding codes are for antennas in your area. These ordinances vary from state to state and I'll leave that one up to you. In an impending thunderstorm, disconnect your cable at the scanner and place the coax connector in a tall DRY glass jar away from your radio and other electrical items. This will act as an open circut and will not look like a path to ground to a nasty old lighting bolt. BUT, that being said, I have yet to find ANYTHING that will protect a feedline in a direct hit.

Guy the mast just above where the second and third pipes join and bring three guy wires down at a 45 degree angle 120 degrees apart to eye screws in the roof (use silicone sealant around the lag) or long pipes driven into the ground at an angle away from the mast. You'll have to use the triangle leg formula for a right triangle to calculate the length of the guy wires.

The nearby woods is not an issue - but since your new mast will probably be the tallest thing close to your residence, please do the lightning protection to code. Best of luck.

 

[maddogdecker]

Thanks RevGary I will look into it.

 

[fuzzymoto]

I have a 20-176 and an ST-2 Scantenna. Both are mounted on the same 10-foot mast which is mounted to the eaves of my upper roof on some angle iron. I do not use guy wires. I have a ground wire fomr the mast to a grounding rod and anothe rgrounding wire from a grounding block. I use RG-6 (former sattelite coax) and YES I do disconnect it from my scanners when not in use (for fear of lightning)....although I suspect in a lightning hit situation even disconecting the wires may not protect the equipment unless you get the coax ends far away (which I can't conveniently do). Both antenna do great. They say neither does well on 800Mhz but what little 800Mhz I have comes in OK for me. I'm up about 30 or 40 feet depending on how you measure (my yard slopes quite a bit). I'd be happy to answer any setup questions I may not have answered.

I sit up pretty high (my house) and I get lots of agencies 40 or 50 miles away pretty easily.

 

[Al42]

The 176 only has a capture area of appx 18" + 6" + 6" = 30". Measure the length of each element on a Scantenna and add them up. Compair to the 176.

You're treating all the elements on the Scantenna as if they were active on all frequencies - they're not. The capture area is each element on its frequency. The Scantenna is a simple dipole - not much capture area.