Wednesday, March 29, 2023

EI9KP to carry out Low-Band VHF Propagation Tests on Sat 1st & Sun 2nd Apr 2023


Back in January and February of 2023, Phil EI9KP carried out some propagation tests on the 34 MHz band. These tests are possible because the radio amateurs in Ireland are allowed to use a large part of the low band VHF spectrum.

Jan 2023 results HERE

Feb 2023 results HERE

On Saturday 1st & Sunday 2nd April 2023, EI9KP will be carrying out more propagation tests but this time on five frequencies from 32 MHz to  36 MHz

His supervised 1-watt beacon will operate from 08:00 UTC to 19:00 UTC on both days. The purpose of these tests is to investigate F2 layer propagation at this point in the solar cycle. There is a possibility of some Sporadic-E propagation as well.


EI9KP writes... "The test beacon is now a time slot beacon and can run a different frequency for each time slot, from 32MHz to 36MHz. There are 5 time slots available, being minutes [00], [01], [02], [03] and [04].  Each time slot will have the sequence: 2*FT8, 2*CW followed by a short carrier.  The time slots repeat at 5, 10, 15, etc., minutes.

The time slots and frequencies are:

TS     Frequency   USB dial (kHz)
[00]  32013         32012.200
[01]  33013         33012.200
[02]  34013         34012.200
[03]  35013         35012.200
[04]  36013         36012.200

The CW and carrier should appear at 800Hz on the waterfall and the FT8 signal a little higher.  The beacon frequency is synchronised to GPS and should have an accuracy of 1Hz or better.  The antenna is a dipole in vertical polarisation, beacon power is still 1W."

Coverage Area: Considering that the tests will be done at the very start of April, there should be some F2-layer propagation still about. If my 28 MHz WSPR reception reports are anything to go by then a key target will be the eastern half of the USA.

The key difference between this test and the previous ones is of course the lower frequency of 32 MHz. Not only is that more likely to be propagated by the F2 layer in the ionosphere but it's also likely that a lot of people may be listening with antennas designed for the 28 MHz (10m) band and they might perform better at 32 MHz as opposed to 34 MHz.

As noted earlier, the Sporadic-E season in the northern hemisphere should be starting in April and there is a possibility of some Sp-E to Europe during the tests.

Antenna: The antenna that Phil is using is shown on the left.

The element on the right is a half-wave dipole for 33 MHz with an adjustable capacity hat.

The element on the left is a dipole is parasitic dipole for 36 MHz which is coupled by its proximity to the main 33 MHz dipole. The purpose of this element is to extend the VSWR bandwidth of the antenna so that it can cover from 32 MHz to 36 MHz.

The antenna is mounted on a fibreglass mast.

The coax feed is probably a little bit too close and may distort the radiation pattern somewhat but Phil reports that the VSWR is acceptable at 1.6 and below.

Reports: Reports to EI9KP on QRZ or you can leave a comment here.




2 comments:

scott said...

good luck friend. so glad to see some use of vhf low band ... US has a lot of amateur allocations but nothing in vhf low yet, not much happening there since the 80s ... i did NOT hear your beacon here. 10m is open between north and south america only at this time. 73 scott k9my

Anonymous said...

I monitored the beacon on both days during several hours of the days at my QTH in locator io53ot.
I used two transceivers- an ICOM 7200 and a Yaesu FT857D. Both TRX had Windom antennas for reception.
I copied the signals on all 5 frequencies with both TRX. The signals on the Yaesu were a bit weaker than on the ICOM. The signal meter showed no bar on the Yaesu- while on the ICOM I had at least one bar, sometimes two.
33,34,35 and 36 MHz all had the same signal strengths- I'll give it a 51 on the Yaesu and a 52 on the ICOM. The signal on 32 MHz was weaker- on both TRX. I'll give it a 31 on the Yaesu and a 41 on the ICOM.
There was a noticeable fading on all 5 frequencies. Slow QSB, not too deep though.

73 de3 Michael/ei3gyb