4000km Trans-Atlantic opening on the 88-108 MHz FM band from Spain to Newfoundland - 29th May 2025

On the 29th of May 2025, FM DXer Larry Horlick, VO1FOG in Newfoundland, Canada managed to hear FM radio stations 88 to 108 MHz band from the Azores and Spain.

Details of the opening extracted from the FMLIST website are shown below. 

UTC QRG ITU Station, location Details, remarks Distance km kW ERP Pol

1012 90.50 AZR RTP Antena 1, Serra de Santa Bárbara (tce) PI logged: 832E PS logged: ANTENA_1   2309 35 h

1108 98.20 E Oxígeno Europa Radio, Jerez de la Frontera/San Cristóbal (AND-CA) PI logged: EE26 PS logged: OXIGENO_ LATINAFM  4004 0.5

2230 90.50 AZR RTP Antena 1, Serra de Santa Bárbara (tce) PI logged: 832E 2309  35 h

2231 88.90 AZR RTP Antena 1, Horta-Cabeço Gordo (fai) // 88.9, 2218  9.1 c

The log above shows two openings on the 29th of May 2025. In the morning opening from 10:12 to 11:08 UTC, Larry logged RTP Antena 1 on the Azores (2309 kms) and Oxígeno Europa Radio near Cadiz in the south of Spain (4004 kms). In the evening, there was another opening to Azores again around 22:30 UTC.

While the Azores reception can be easily explained by one single Sporadic-E hop, the 4004 km distance from the south of Spain to Newfoundland requires two Sporadic-E hops to line up which is much rarer at these VHF frequencies.

This isn't the first time that Larry has heard trans-Atlantic FM radio stations and details of previous openings can be seen on my 88-108 MHz page.

In conclusion: There have been plenty of reports of Sporadic-E openings in Europe and North America over the last few weeks as the summer season kicks off. The vast majority of the reports are one hop Sporadic-E which are of limited interest. 

Reports of VHF signals on the FM band crossing the Atlantic however are exceptional. Signals on the VHF bands are often quoted as being 'line of sight' and yet here we have an example of a 98 MHz signal spanning two continents.

It also hints at the possibility of whether higher frequencies could span the Atlantic? Spain or Portugal to Newfoundland on 144 MHz?

FM radio stations on the Azores heard in Newfoundland - 13th May 2025

On the 13th of May 2025, FM DXer Larry Horlick, VO1FOG in Newfoundland managed to log quite a number of FM radio stations from the Azore Islands.

The stations logged were in the range of 87.6 to 103.0 MHz and the distances were in the region of 2000 to 2600 kms.

It's very likely that the propagation mode was one hop Sporadic-E with some degree of tropo at one or both ends.

Most of the stations were logged in the period from 14:01 to 14:47 UTC although there are two from 15:21 and 18:14.

The power of the transmitters ranged from an EPR of 40-kilowatts down to as low as 50-watts.

This isn't the first time that Larry has logged the Azores but it's always interesting to see reports of stations from the Azores being heard in North America. It's also relatively early in the Sporadic-E season for such signals.

This is a selection of the radio stations that Larry heard...

Links...
1) The source of the above information is FMLIST.ORG
2) For more information on long distance paths on the FM band, see my 88-108 MHz page.

36.9 MHz Doppler Radar Antenna at the White Sands Missile Range Museum

It's always interesting to read about how the low VHF band above 30 MHz was used over the years for various applications. In the United States in the decades after World War 2, they used doppler shift on the low VHF band to find the location of rockets that had been launched.

The antenna above is a helical antenna operating at 36.9 MHz which sent a radio beam up towards the rocket after launch. A series of similar receiving systems would then pick up the reflected signal which would be shifted slightly in frequency due to the motion of the rocket i.e. the reflected signals would have some doppler shift.

By examining the data afterwards, the exact position of the rocket at any particular time could be calculated. 

The antenna shown above is at the White Sands Missile Range Museum in New Mexico. If we examine it closely then we can see that it has three turns so we can estimate the gain to be roughly 8dBd, have a beamwidth of about 60 degrees and is of course using circular polarisation.

The plaque on display reads as follows...

"36.9 Megahertz Helix Antenna Doppler Velocity and Position (DOVAP)

Reference Transmitter Antenna

Developed during World War II by the Germans as part of a V-2 guidance and control system, DOVAP traced the course of a rocket using the Doppler Effect caused by a target moving relative to a ground transmitter and receiving stations.

Unlike radar, Dovap did not allow scientists to "see" the rocket on a screen. Instead, it sent up radio waves, which were received and rebroadcast back to earth by the rocket. The returned waves combined with the original ground broadcast and produced a musical tone which varied with the rocket's speed - the faster the rocket, the higher the pitch.

DOVAP data was extremely accurate: it could place a rocket's position at 100 miles up within 50 feet. It could collect data at the extreme altitudes of 100 to 300 miles. Dovap's disadvantage was that it took 3 to 4 weeks to reduce the data.

The antenna is a helix because of its physical and electronic characteristics. A helix is simple to construct and operate, provides necessary signal gain and directivity, and can be operated in several modes or polarizations.

The DOVAP system provided trajectory data and ground guidance for most of the early rocket systems: Corporal, Sergeant, Honest John, Little John, Redstone, and Aerobee Upper Atmosphere programs.

This particular antenna was built in the mid-1960s near C Station. Like much of the early instrumentation used here, it was designed and built at White Sands Missile Range.

Erected by White Sands Missile Range Museum. (Marker Number 06.099.)"