Antenna Recommendation for UHF-T
Why buy something when you can make something? Since you already have coax out there, how about making an antenna from the coax?



The "metal tubing" is the shield of the coax, and the "solid metal or tubing" is the center conductor. So you just strip a long length of the coax, then carefully fold the shield back over the coax. Keep in mind the shield will get shorter as you expand its diameter to fit over itself, so strip it a bit longer then trim it to length.

The whole arrangement should be half the wavelength long (so each section is a quarter wavelength). As an approximation:

$$ \text{length in feet} = 460 / f $$

Where \$f\$ is the frequency in MHz. For your application, \$ 460/495 \approx 0.93 ft \approx 11.2 in \$.

You can cut it a bit long then fine-tune the length if you have the appropriate equipment or through trial-and-error, but that may be unnecessary.

Also, take care to weatherproof the end of the coax. You don't want water getting inside the coax. There are any number of products out there, but some epoxy thinned with alcohol brushed on the end also works great.

Of course this isn't the most perfect antenna design. But if you are getting some signal without any antenna at all, this will be at least an order of magnitude better, and probably, good enough.