Showing posts with label 10 meters. Show all posts
Showing posts with label 10 meters. Show all posts

Wednesday, December 8, 2021

More information about the proposed Amateur TV experiments at 29.250 MHz & 51.7 MHz

In a previous post in August of 2021, I outlined how some radio amateurs in Europe plan to experiment with digital ATV (Amateur TV) on the 10-metre band in the Summer of 2022. That post generated quite a bit of interest.

On Monday the 6th of December 2021, the BATC streamed a YouTube presentation about current Amateur TV techniques and activity as part of the RSGB Tonight at 8 series.

While the video is about 75 minutes in length, the piece I found really interesting was about the proposed ATV experiments at 29.250 MHz and 51.7 MHz. They refer to these as the 'lower ATV bands'.

Amateur TV up to now has normally been used on the UHF and microwave bands. This new development at 29 MHz and 51 MHz will potentially allow ATV signals to be sent on frequencies which will achieve much greater distances via the ionosphere - i.e Sporadic-E and F2 layer.

I find it amazing that there is the potential of sending amateur TV signals between say Europe and  North America on the 10-metre band.

 The presentation with time guides are shown below...


Video guide...
03:35: Introduction starts
05:15: G8GTZ begins his presentation
06:55: What is ATV - Amateur TeleVision / Why amateur television? / ATV is going digital
12:00: Analogue V Digital ATV / Reduced bandwidth (RB-TV) / 80 kHz RBTV
16:30: UK ATV activity and repeaters
20:45: ATV on the air - 1 The lower ATV bands
22:45: ATV on the air - 2 Low cost 5.6 GHz FM ATV with example contact
29:45: ATV on the air 3 - DATV on QO100 (Geostationary satellite)
38:20 - DATV equipment / Getting started / Ryde DATV receiver / Portsdown DATV transceiver / DATV receive system / DATV transmit system / 
57:55: Info about British Amateur Television Club (BATC)
1:01:00 Q &A session

I am told that the numbers involved are likely to be small with perhaps something like 20-30 stations taking part. Special boards are being developed at present and no doubt, these will be be got ready for the Sporadic-E season next May.

It would be very interesting if some radio amateurs in North America got interested in this project.

Links...
1) BATC website... https://batc.org.uk/

Saturday, November 26, 2016

Three Eight Wave Ground Plane Antenna for 10 Metres

Over the years, I have collected many old magazine articles and it seems to be a waste to have them buried away in a folder. This one is for a 3/8 wave ground plane antenna for 28 MHz and hopefully it might encourage someone to experiment and build one.



The principle is pretty easy. A normal dipole in free space normally has a 72 Ohm feed point impedance. A quarter wave ground plane is half this...about 36 Ohms.

By extending the antenna from a quarter wave to a three-eight wave, the maximum current point moves from the base to further up the radiating element. This has the effect of lowering the angle of radiation which is a plus.

The longer three-eight wave antenna now has a reactive feed point (inductive) as it's too long. This is tuned out with a series capacitor and it should be able to get close to 50 Ohms.

This antenna would suit someone who can only put up a quarter wave ground plane for 10 metres and wants better performance.

The article from the March 1983 edition of Short Wave Magazine is shown below...