Using a UHF yagi in a metro area?

[Gilligan]

I have a Pro-97 that I just bought and I fell in love with its receiver. It's much more sensitive than my BC246T and so I'm discovering a lot of stuff to listen to that I couldn't hear before. I've wanted to invest in a UHF beam antenna for several reasons, but before I spend a good deal of money on one, I thought I'd ask the antenna experts if this is really such a wise idea. Here's my thoughts, so please let me know what you think.

I am not a casual scanner listener. I use my radio much more for identifying unknown users than listening to already identified users. I do a lot of searching in the UHF business band (450-470 MHz). I also love the Signal Stalker II feature on my Pro-97, which works very well with even just the rubber handheld antenna. But I want to get more out of my radio. I currently live in the Oklahoma City metro area, so there is the potential for the usual metro interference (pagers, etc). It has not been a problem as of yet.

I want to get a beam so I can:
1) Point it at specific businesses in a mobile application
2) Point it at specific (rural) towns to target their communications
3) Point it towards downtown to improve reception

Regarding #1, would it be practical to use a yagi in a vehicle at a range of 25-100 yards from a building (ex. parking lot)? I plan to make heavy use of Signal Stalker II for #1 (not #2 or #3). Would there be a reason that it would not work as I expect?

The big question for me as well is what kind of results can I expect? I'm looking at the Antenex YS45012 yagi beam (see also here) that has 11 dBd gain. Using such an antenna, what kind of increase in range could I expect both at ground level (in a vehicle) or roof height (2nd floor)? I've never used a yagi so I don't know if I'm expecting too much from it. And $100+ is pretty steep on a college student's budget for something that really do what I want it to.

 

[n5ims]

Portable beam antennas

It was quite common for hams in contests where a hidden low power transmitter (manned, of course) is located by others, for folks to walk around with small beam antennas in an attempt to locate the transmitter. While these were normally contests, they were practice for locating missing people or downed aircraft.

Now, this has mostly been replaced by direction finding equipment, a few hams still use this old method. Often, there are special prizes for folks using the 'old way'.

With the enhanced 'security', I'd worry about sitting near a building or office park with a visible antenna. Please make sure you have ID and a good story why you're there incase security pays you a visit. Other than this, using a small beam should do what you want.

 

[Gilligan]

It was quite common for hams in contests where a hidden low power transmitter (manned, of course) is located by others, for folks to walk around with small beam antennas in an attempt to locate the transmitter.

Foxhunts. Completely forgot about them. That sounds like a fair equal to the idea.

Please make sure you have ID and a good story why you're there incase security pays you a visit.

I've actually worked a lot of security, so I know how to avoid them and what they can and can't do. And honestly, the places I usually search out don't have security, especially during the day. Now the cops on the other hand... Your comments are appreciated.

 

[iMONITOR]

Using a Yagi in an RF populated area could cause overload, especially from pagers. You might need to invest in a PAR Filter such as this:

PAR 462-HT Pager Interference Filter
http://www.grove-ent.com/FTR462.html


Check eBay for deals on Yagi's, like this one:
http://cgi.ebay.com/Bluewave-Yagi-430-450-MHz-7-5-dB-Microwave-Antenna-NEW_W0QQitemZ260079066758QQihZ016QQcategoryZ53107QQrdZ1QQcmdZViewItem