That particular path is not as easy as it sounds. Typical single-hop distances via the F2
layer from the west coast get you about Pennsylvania or so, but it usually takes 2 hops
to reach New England. That means that the ionospheric conditions need to be favorable
in two areas to make contact rather than just one: you will be more dependent on
ionospheric conditions than is often the case for shorter paths.
There are a number of programs available that will help you to choose the optimum
operating frequencies based on current ionospheric conditions. I have had good results
with some of the tools provided by the Australian Ionospheric Prediction Service, but
there are others that may also work for you:http://www.ips.gov.au/HF_Systems/7/1
There are two general categories of changes you can make to your antenna that will
help make the path more reliable: improve the radiation at the optimum vertical angle
for the path, and increase the gain in the desired azimuth direction.
Vertical angle is often a matter of getting the antenna up high enough. Depending on
conditions, the required vertical angle is probably around 15 - 30 degrees or so. If
we choose 25 degrees as an example, we can plot the relative radiation at this angle
for a dipole at various heights above ground:
25' . . 0.3 dB
40' . . 2.3 dB
50' . . 3.8 dB
60' . . 5.5 dB
70' . . 7.2 dB
Just raising your antenna from 25' to about 50' would increase your signal 3dB, which
is equivalent to running twice the power. Going to 65' is like using a 400W amp.
This may not make or break the ability to make a contact, but it will certainly make it
easier in marginal conditions.
This is for 40m: on 20m it doesn't require as much height to optimize the takeoff angle.
Sometimes vertical polarization may give better results if you are limited in height - this
will depend to a large extent on the local soil conditions.
But the concept is that, for a specific path, there will be an optimum range of vertical
angles of radiation, and antenna height (and polarization) can be adjusted to provide
the best radiation at that vertical angle.
We're more used to considering the azimuth directivity: aiming your antenna in the
desired direction. If you can string up your antenna broadside to the desired
direction and make it longer you can get some useful gain. There are various other
sorts of wire beams you can try as well, depending on the orientation of your
supports relative to the required direction.
Each of these will improve your chances of making the desired contacts. I'd start
by looking at plots of the optimum frequency vs. time of day to cover the path:
running more power isn't going to help if the ionospheric isn't cooperative.