Summer 2007 Issue
As many VHF operators know, it is a real challenge to make long-range contacts on 144 and 432 MHz via terrestrial means. This is not only because of the need to take advantage of propagation conditions when they happen—such as tropospheric ducting, sporadic-E, and aurora—but also because of the apparent lack of monitoring the calling frequencies on these bands on a daily basis by many VHF operators.
Indeed, for the most part these bands do come alive, to a degree, with increased activity during the major VHF contests throughout the year, particularly the ARRL’s VHF contests in January, June, and September, when all VHF bands from 50 MHz up to the microwaves are utilized. The CQ WW VHF Contest in July utilizes 50 and 144 MHz, and often both of these bands enjoy significant activity during the contest period.
This brings up the real question: What about the rest of the year? Enhanced propagation conditions are present on 144 MHz and 432 MHz at certain times of the year and often are missed because of the lack of day-to-day monitoring by VHF operators. Both of these bands are included in a number of current HF-plus-VHF mode radios, so it becomes a matter of knowing when to monitor the bands.
The following is a brief overview of some of
my limited successes chasing long-range contacts in the weak-signal
portion (CW and SSB) of 144 MHz and 432 MHz using a portable station, as I
do not have a permanent 2-meter station in my house. As I have found, you
can have fun chasing contacts on these two bands.
Later on in this article we will discuss the various propagation modes that can allow for long-range contacts on 144 and 432 MHz. However, the first question we need to ask is what type of equipment is needed to capitalize on some of these propagation modes and make contacts.
Because of the size of the wavelength for the
VHF bands, it is not difficult to have a well-equipped station at home,
where a multi-element Yagi is used up 50 to 100 feet on a tower. In
addition to the multi-band radios that have 144 MHz and 432 MHz, there are
plenty of linear amplifiers available for these frequencies. A home
station with multi-element Yagis and amplifiers will do well with all of
the propagation modes mentioned earlier in the article.
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