How are you defining "poor" reception? And what is it you are trying to receive? Answering those questions will help other make appropriate recommendations.
Without the answers to those questions, I'm going to make some assumptions and a recommendation:
ASSUMPTIONS
- You can't get higher (roof) in your building
- You can't get outside your building
- You want to receive a wide range of frequencies in the popular "scanner bands"
- You don't want to spend much on a new antenna until you find something that works better that what you bought (Which shouldn't be hard to improve upon)
Assuming all of the above are correct, I would suggest this -
Homebrewed Off-Center Fed Dipole - The RadioReference Wiki
Yes... I know it looks like the one you already have. But there are some key differences, starting with the fact that what you have may be nothing more than a vertical dipole in a PVC pipe; or worse, a single vertical element that is no different than the antenna that came with your scanner. But the OCFD is a proven performer when you need something indoors, and if built exactly to the specs in the RR Wiki page (above). And if you want to read how well it works, search "OCFD" here on RR.
If you want to spend less to do a quick check whether the OCFD will work for you, scroll down the Wiki page and you'll see the same antenna made from simple hookup / bell wire. You can slap it together in about 15 min and for $10 in parts from any home store or Walmart. If it works and you like it, make the copper pipe version.
The other low cost alternative: one of those "leaf" or "patch" TV antennas you get in any home store or Walmart. But before we can recommend one of them it would be best to know what frequency ranges you want to receive, since some of them do not handle VHF Low band. (The OCFD does.)
UPDATE: Just noticed you are in St. Croix county, WI. And RR DB shows mostly VHF and UHF. So the OCFD could serve you well. But you may also be able to use one of the TV antennas I wrote about.