Summer 2007 Issue

VHF Propagation Hunter
Tips for Long-Range Terrestrial Contacts
on 144 and 432 MHz

WB2AMU presents a brief overview of his chase for long-distance contacts in the weak-signal portion of 144 and 432 MHz while operating portable.

By Ken Neubeck, WB2AMU

This is a practical portable setup that involves a three-element 2-meter Yagi manufactured by MFJ. It is mounted on a telescope tripod that is resting on the roof of WB2AMU’s Chevy Malibu. A short run of RG-8U coax connects the antenna to an FT-100 resting on the dashboard of the car. The antenna installation is very steady, as the weight of the tripod and beam is sufficient to stay in place during moderate wind conditions. This setup works well in the middle of a parking lot. (Photo by the author)

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.

Equipment That Can Be Usednfor the Chase

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.
However, when working long-range contacts, it is possible to do quite well with portable and mobile setups for these bands. A major advantage of a portable setup is the ability to pick out a suitable site in terms of height and reduction in noise level. Indeed, VHF hill-topping has been a pastime of mine for close to 40 years. Major improvements in equipment and antennas have made my operations more feasible without a lot of effort.

Click here to return to Summer 2007 highlights

Click here to subscribe to VHF

_________________

© Copyright 2007, CQ Communications, Inc. All rights reserved. This material may not be reproduced or republished, including posting to a website, in part or in whole, by any means, without the express written permission of the publisher, CQ Communications, Inc. Hyperlinks to this page are permitted.