Howard a ducikie is, in general, a compromise antenna if you think of using it on a wide range of frequencies (here, I'm thinking you mean both civil and milair). While you are correct that a good antenna and coax (such as the Diamond discone, ScanTenna or NilJon) will help, there'a downside - and it has to do with your location.
I'm somewhat familiar with that area, and know very well that there are numerous paging and business transmitters in the area, not to mentioin at least 2 of Baltimore county's 800 towers. All this adds up to a very real possibility of overloading - and that will mean hearing distorted garbage coming in on the aircraft bands where you don't want it. You may well need to invest in a PAR filter - they work quite well, and have used them on several radios over the years.
A somewhat cheaper solution might be to get a mag mount and put it up nice and high (say in an attic) with a large conductive surface underneath it. If we're talking milair, I asked a similar question on the 396 group and was told that the Diamond 220 mhz ham antennas work quite well as milair antennas. In addition, NorthWest Radio has a nice overview of mobile antennas - the link for which we have on the Antennas wiki. I would not overlook using the NilJon as well in this configuration.
Don't be too surprised by this - handhelds simply can't always hold up to urban signal levels. Their design simply doesn't always allow for it. Good size outdoor antennas are nice, but you have to buy them with both your environment and radio in mind.
73s Mike
