N5PA Website

Updated:  24-May-2013 1:05pm 
  Clear Temperature: 81.0°F   +1.7°F/hr Humidity: 58% Dew Point: 64.8°F Wind: NNE  2.3 mph Gust: 10.0 mph Barometer: 30.175 inHg   Steady Rain Today: 0.00 in UV Index: 0.0  None

VHF/UHF Weak Signal Page

Current 144 MHz Band Conditions (Click for Details)
WWV Alert Message		Data from DXRobot
144 Es in N.A.	Aurora	144 Es in Europe	Today's MUF & Es
The "Today's MUF / Es" shows the daily 144MHz High MUF and Es times. The blue bar indicates 50MHz Es and the green bar indicates 70MHz Es times. The graphic is updated every 5 minutes.
Last 100 Spots on 50 MHz (And other bands)
ON4KST 50 MHz Chat (And other bands)

Solar-Terrestrial Data

G4FON - Koch Method CW Trainer - Software Download

I have always had an interest in the VHF/UHF Weak Signal segment of our Ham Radio hobby. Back in my younger days I worked a lot of 50 MHz, 144 MHz, 220 MHz, and 432 MHz. I worked some EME (Earth-Moon-Earth, or Moon Bounce) during those days back in the 70's and early 80's. You may ask what do I mean by "VHF/UHF Weak Signal"? What I am talking about is mainly working in the CW and SSB segments of these bands over great distances or running EME. I worked satellites during those times, also. I had several great mentors in the VHF/UHF Weak Signal arena. George Chaney, W5JTL (SK) of Vicksburg, MS; Rex Turner, W5RCI (SK) of Marks, MS; Paul Wilson, W4HHK (SK) of Collierville, TN; and George Tew, NC5Y (SK) of Jackson, MS were my mentors in this area of our hobby. You can read about them on my "Mentors" page.

George Chaney, Rex, and I would talk every morning and every night. We would normally get on around six in the morning and at eight at night. We would talk about construction or antenna projects we were working on. Back in those days I had stepped up to a Kenwood TS-700S. This was the 10 watt all mode 2 meter transceiver. When trying to work contests or distant weak signal stations I had a pair of 4CX250B's that could be easily driven by this rig. I remember one Sunday night George Chaney and I were talking to each other. I was running about 3 watts and had my beam pointed towards Vicksburg. After awhile, a station broke in and asked where we were. George went back to him and told him and he replied, that he was a Wa2 in Poughkeepsie, NY. For the next hour or so, the lower end of 144 MHz sounded like 20 meters during the CQWW DX Contest! That was some of the best fun I ever had. I worked tons of new states and grids that night and if it were not for all the QRM on the bands, I could have worked even more. I never turned my antenna and never flipped on the amp!

VHF(144 MHz) Propagation Map:

This map uses APRS data to compile it’s 144 MHz propagation. It is real time, but you must manually Refresh this page. You must Zoom in for more detail. Look for yellow and red areas and hover over them to display the callsigns. Click on the callsign for their detailed information. Distance is measured in kilometers.

VHF/UHF Propagation Modes:

VHF and UHF are not thought to be bands where propagation affects your signal, but there are times when your signal will propagate well beyond their normal limits. VHF/UHF "Openings" happen sporatically and you cannot predict them as well as HF propagation. VHF and UHF can be affected by the following conditions, though:

Tropo - Tropospheric signals happen in the part of the atmosphere close to the surface and up to about 25,000 feet or 7,620 meters. Such signals are thus directly affected by weather systems up to several hundred miles. A major storm system or a cold front that is approaching can create Tropo openings. As it cools in the evenings it can create Tropo openings, as it is in the morning when the inverse happens, cool to warm conditions. When it is very warm and there is a high pressure system with cloudless and windless skies, Tropo will improve weak signals from distant stations. Another symptom of Tropo conditions is when adjacent TV stations on the same channel start to interfere with each other. Summer and Fall are the best times for Tropo openings and UHF signals can be enhance to distances up to about 1,000 miles or 1,600 kilometers or more for single hops. At sunset the upper air and surface air cool at different rates causing a temperature inversion. A similar effect happens at sunrise. Normally VHF/UHF signals travel into space but the inversion effectively reduces sky wave radiation from a transmitter. With temperature inversion the signal is refracted over the horizon rather than continuing into outer space. Fog also produces Tropo openings. The heating of the upper level of the fog causes a temperature inversion. It occurs in the evening an continues overnight and clears at sunrise over a period of around 4 – 5 hours.

Sporadic E - Sporatic E is an unusual form of radio propagation using characteristics of the Earth's Ionosphere. Whereas most forms of skywave propagation use the normal and cyclic ionization properties of the ionosphere's F region to refract or bend radio signals back toward the Earth's surface, Sporadic E propagation bounces signals off smaller "clouds" of unusually ionized atmospheric gas in the lower E region that is located at altitudes of approximately 55 to 100 miles or 90 to 160 km. This occasionally allows for long-distance communication at VHF frequencies not usually well-suited to such communication. Sporadic E occurs during June-July and early August and again in December and January. As the name suggests this condition is very sporadic and learn how to be patient in your waiting for it to occur.

Aurora - The northern lights or aurora borealis occurs in the northern parts of Canada and can also be seen from northern United States, Europe, and Asia. The southern lights or aurora australis happen in high southern latitudes in Antarctica, Australia, New Zealand, and South Ameriaca. Aurora is caused by a solar storm or Coronal Mass Ejection (CME) that hits the Earth's Magnetosphere and can have an effect on radio propagation. If can affect VHF and UHF propagation in a positive manner and HF propagation in a negative manner. To use the aurora you should point your antenna north to work a station to the south as signals bounce back from the aurora in the Northern Hemisphere and the opposite in the Southern Hemisphere.

VHF/UHF Clubs:

• Mississippi Coast VHF Society
• SMIRK - Six Meter International Radio Klub
• Side Winders on Two Radio Club
• Central States VHF Society
• North East Weak Signal Group
• Kansas City Grid Bandits
• The Northern Lights Radio Society
• K8GP Grid Pirates Contest Group " Delmarva VHF and Microwave Society
• AA4ZZ Contest Team
• Carolina DX Association
• Roadrunners Microwave Group
• Ultra Highs Weak Signal Society
• The Society of Midwest Contesters
• Pacific Northwest VHF Society
• North Texas Microwave Society
• Mount Greylock Expeditionary Force
• Southeastern VHF Society
• Florida Weak Signal Society
• Badger Contesters
• Mt. Airy VHF Radio Club
• 144.205 Morning Group
• KC9BQA - Promoting VHF/UHF in Wisconsin and the Upper Midwest
• Alaska VHF-Up Group
• Rochester VHF Group
• Rocky Mountain VHF Plus
• Texas VHF

VHF/UHF Resources:

• ON4KST 50 MHz Chat (And other bands)
• Real Time VHF/UHF QSO Propagation Map
• 144 MHz APRS VHF Propagation Map (Zoom In to View)
• William Hepburn's Worldwide Tropospheric Ducting Forecasts
• 144 Mhz Propagation Logger
• 220 Mhz Propagation Logger
• UHF Propagation Logger
• 50 Mhz Propagation Logger
• VHF Schedule Setup
• VHF QSO Link
• Current Weather Fronts
• Propagation
• Weather
• Download WSJT Software for Meteor Scatter
• VHF/UHF Mailing List
• CQ VHF Magazine Website
• The K0NR Radio Site
• Icom U.S. Grid Square Map
• Contesting.com Mail Archives
• The DK5YA VHF Page