Date   

Re: Authority to operate on 24GHz

Clive Elliott GW4MBS
 

Of course historically we used 24,192 as it was linked to G3BNL's magic number 1152:
2 x 1152 = 2304
3 x 1152 = 3456
5 x 1152 = 5760
9 x 1152 = 10368
21 x 1152 = 24192
144 + 1152 = 1296
 
--
Clive GW4MBS (ex-G8ADP)
Pottering on 6m/4m/2m/70cm/23cm in a valley in IO71XW where any QSO is a triumph of optimism over geography!


Activity List for the UK Microwave Group 24/47/76GHz Contest Sunday 20th October

John Quarmby
 

Thanks for your inputs, here's the activity list for tomorrow's mm-wave contest:

Call: G4BAO
Locator: JO02cg33
Bands: 24GHz only
1Watt to 60cm offset @ 8 magl
Digimodes available (JT4G preferred)
Talkback: 144.390 and ON4KST and (if you must) Zello

Call: G1EHF/P
Locator: IO91GI (Walbury Hill)
Bands: 24GHz GPS lock, 100mW 30cm dish
Also testing second system 24GHz GPS lock, 15mW 60cm dish
Weather permitting

Call: G0JBA
Locator: JO01PG63 (Sandwich)
Bands: 24GHz, GPS locked, 1.8Watt to 40cm offset dish at 15M agl
Talkback: KST Chat

Call: G4SJH/P
Locator: IO91GI44 (Walbury Hill)
Bands: 24GHz 10mW 40cm dish
Talkback: 144.390 and KST
Weather permitting

Call: G8CUB/P
Locator: 10.00 local Danbury JO01GR81
13.00 local  Buckland IO91XX77
14.30 local  Therfield IO92XA03
24GHz 3W 30cm dish
47GHz 50mW 30cm dish
76GHz 50mW 30 cm dish
At 1.5m agl
Talkback: 144.390 & KST
All times apx.

Call: G8GTZ/P
Locator: IO91 (weather dependent)
Maybe from 10am but definitely from 1pm
24Ghz 1 watt 30cm
76GHz UKMicrowave Group loan kit
Talkback = 144.390 and KST

Call: G4LDR/P
Locator: Stockbridge (IO91GC68)
Winchester (IO91JB00)
Petersfield (IO90MX13)
24GHz 1W 30cm dish
47GHz 50mW 30cm dish
76GHz 50mW 25 cm dish/or 20cm horn
Talkback 144.390MHz +/-QSY
Times throughout. Weather dependent.

Call: G3ZME/P
Locator: IO82QL83 (Brown Clee)
Band: 24 GHz (only) 0.5W, 65cm dish
Talkback: 144.390 (mainly). Also probably 'KST and Zello.
Times: 10:45-ish onwards

I hope the weather is favourable and that conditions are suitable, enjoy the day.

73

John G3XDY


Virus-free. www.avast.com


Re: Authority to operate on 24GHz

John Quarmby
 

Another piece of the puzzle was that the amateur activity moved down from 24192 to 24048 to sit inside the Primary allocation.

73

John G3XDY


On 19/10/2019 12:47, Murray Niman wrote:
The history and answers are here....
https://rsgb.org/main/operating/licensing-novs-visitors/uk-licensing/licensing-history/

It was fixed when BR68 was introduced

73

   Murray G6JYB 

Virus-free. www.avast.com


Re: Mesh size for 10GHz

KENT BRITAIN
 

30/4 would be more like 7-8 mm and the usual 'Rule-of-Thumb' is 1/10 wavelength or 3 mm.

Kent

On Saturday, October 19, 2019, 1:37:49 PM CDT, John E. Beech <john@...> wrote:


I don't think it will make any difference. The criterium for a mesh dish is that the mesh size must be smaller than a quarter wavelength at the frequency in use ie < 15 mm for 10 GHz.

de John G8SEQ

>  -------Original Message-------
>  From: Dom Baines M1KTA via Groups.Io <dombaines=yahoo.com@groups.io>
>  To: UKMicrowaves@groups.io <UKMicrowaves@groups.io>
>  Subject: [UKMicrowaves] Mesh size for 10GHz
>  Sent: Oct 19 '19 18:27

>  Was suggested ask here so here goes.

>  Bit of a rookie so might be a daft question:

>  If using a mesh reflector for a dish with size 2.5mm x 4.5mm does
>  this mean it will be fine in one plane but might be very lossy in the
>  other at 10Hz as 1/10th is c3.0mm. But by how much?
>  Should I cross the mesh so the centre (opposite prime focus) at least
>  has no opening larger than 2.5mm ?

>  Solid dish had some wind-age issues and moved (understatement) so got
>  to rethink.

>  72

>  Dom
>  M1KTA





Re: Mesh size for 10GHz

Andy G4JNT
 

7.5mm



On Sat, 19 Oct 2019 at 19:37, John E. Beech <john@...> wrote:
I don't think it will make any difference. The criterion for a mesh dish is that the mesh size must be smaller than a quarter wavelength at the frequency in use ie < 15 mm for 10 GHz.

de John G8SEQ


Re: Mesh size for 10GHz

John E. Beech
 

I don't think it will make any difference. The criterium for a mesh dish is that the mesh size must be smaller than a quarter wavelength at the frequency in use ie < 15 mm for 10 GHz.

de John G8SEQ

-------Original Message-------
From: Dom Baines M1KTA via Groups.Io <dombaines=yahoo.com@groups.io>
To: UKMicrowaves@groups.io <UKMicrowaves@groups.io>
Subject: [UKMicrowaves] Mesh size for 10GHz
Sent: Oct 19 '19 18:27

Was suggested ask here so here goes.

Bit of a rookie so might be a daft question:

If using a mesh reflector for a dish with size 2.5mm x 4.5mm does
this mean it will be fine in one plane but might be very lossy in the
other at 10Hz as 1/10th is c3.0mm. But by how much?
Should I cross the mesh so the centre (opposite prime focus) at least
has no opening larger than 2.5mm ?

Solid dish had some wind-age issues and moved (understatement) so got
to rethink.

72

Dom
M1KTA


Mesh size for 10GHz

Dom Baines M1KTA
 

Was suggested ask here so here goes.

Bit of a rookie so might be a daft question:

If using a mesh reflector for a dish with size 2.5mm x 4.5mm does this mean it will be fine in one plane but might be very lossy in the other at 10Hz as 1/10th is c3.0mm. But by how much?
Should I cross the mesh so the centre (opposite prime focus) at least has no opening larger than 2.5mm ?

Solid dish had some wind-age issues and moved (understatement) so got to rethink.

72

Dom
M1KTA


Re: Offset dishes on 24 ghz EME

Dominique Dehays
 

Hi all ,

offset superiority is no longer to demonstrate. Here I very often run sun noise measurements and I have often done the comparison between an offset and a prime focus of the same size ( BTW size is the small dimension of the oval). Most of the time sun noise is 2db better with the offset.

The prime focus we use are very often low f/d dishes , then , feeding them with good efficiency is difficult  but feeding a 0.6 to 0.8 f/d offset is easy.

73

Dom/F6DRO

Le 19/10/2019 à 15:17, Chris Bartram G4DGU a écrit :
Hello Keith,

Offset dishes are probably a better bet for 24G EME than a so-called 'prime-focus' reflector. You are likely to get significantly higher efficiency. Most amateur objections seem to come from a lack of knowledge of the geometry, and a lack of suitable, simple to make, feed designs. You can use an offset dish on the horizon without any penalty, but the mount has to be capable of tilting the dish 'forward' so that the plane of the dish rim is inclined at the offset angle of the reflector. As I resume my own 24GHz EME project (after over a decade's break!) I am planning to use a standard 1.5m TV offset dish. That will replace my old 2.4m offset - which I was then using  quite successfully on 10G EME. For the 2.4m antenna -which had 0.8f/D - I designed a feed horn for 24 based initially on the Skobelev paper referenced in W1GHZ's book. I optimised that design and designed the circular to rectangular WG20 transition using a an EM modelling program.

Dishes/feeds used for point-to-point comms at 24GHz will be optimised for different criteria than those which are necessary for good performance over the EME path, and the feed supplied with the dish may not be particularly ideal for our use.

My old 24GHz feed has been used with a number of typical 0.65f/D 'TV dishes', and it works well. However due to underillumination it doesn't _quite_ get the performance of which those dishes are capable. I will be designing a 0.65 f/D feed once I've finally completed my new dish mount - but don't hold your breath!

73

Chris

G4DGU




Re: Offset dishes on 24 ghz EME

Chris Bartram G4DGU
 

Hello Keith,

Offset dishes are probably a better bet for 24G EME than a so-called 'prime-focus' reflector. You are likely to get significantly higher efficiency. Most amateur objections seem to come from a lack of knowledge of the geometry, and a lack of suitable, simple to make, feed designs. You can use an offset dish on the horizon without any penalty, but the mount has to be capable of tilting the dish 'forward' so that the plane of the dish rim is inclined at the offset angle of the reflector. As I resume my own 24GHz EME project (after over a decade's break!) I am planning to use a standard 1.5m TV offset dish. That will replace my old 2.4m offset - which I was then using  quite successfully on 10G EME. For the 2.4m antenna -which had 0.8f/D - I designed a feed horn for 24 based initially on the Skobelev paper referenced in W1GHZ's book. I optimised that design and designed the circular to rectangular WG20 transition using a an EM modelling program.

Dishes/feeds used for point-to-point comms at 24GHz will be optimised for different criteria than those which are necessary for good performance over the EME path, and the feed supplied with the dish may not be particularly ideal for our use.

My old 24GHz feed has been used with a number of typical 0.65f/D 'TV dishes', and it works well. However due to underillumination it doesn't _quite_ get the performance of which those dishes are capable. I will be designing a 0.65 f/D feed once I've finally completed my new dish mount - but don't hold your breath!

73

Chris

G4DGU


Offset dishes on 24 ghz EME

Keith
 

A Question for those who know :)

Today I was gifted an Andrew Type 960 Class II Dish with mount and feed for Ku band, in its original box and never used. So its a 960 mm dia offset fed dish made to the usual Andrew standards.

I'm thinking it "could" be a better option for portable with my 24 ghz gear for EME. I know how folks many don't rate offset dishes due to the limitations on elevation before they can be used to the best of their abilities, but I'd like to weigh all that up before deciding.

It means I could mount the gear at the feed point rather than behind the other inferior quality prime focus dish I had planned to use.

So opinions from those who have compared prime to offset and suggestions for a suitable feed would be appreciated.

When you google offset dishes for 24 ghz, the hit list is underwhelming :(

Is it because they stink :) or is it just because folks havent written up their experiences ?

I'd like to make an honest assessment without going through all the fuss actually trying it out.

So if anyone has the knowledge or can point me to someones webpage who is using one then mucheous gracias !

Cheers

Keith  VK6KB / VK6EME


Re: Authority to operate on 24GHz

Murray Niman
 

The history and answers are here....
https://rsgb.org/main/operating/licensing-novs-visitors/uk-licensing/licensing-history/

It was fixed when BR68 was introduced

73

   Murray G6JYB 


Re: Authority to operate on 24GHz

Clive Elliott GW4MBS
 

Paul somewhere I have an application form from the 1980s I'll try & dig out.

I have a copy of the requirements issued in 1974. Was that when we got 24GHz to replace 21GHz? I dabbled on that band but there were no similar restrictions then.

I see my first letter of authority limited me to 5w ERP & was renewable annually. A later letter of authority for another site increased ERP to 25w.
--
Clive GW4MBS (ex-G8ADP)
Pottering on 6m/4m/2m/70cm/23cm in a valley in IO71XW where any QSO is a triumph of optimism over geography!


Re: Authority to operate on 24GHz

Paul G8KFW
 

Hi Clive 

That is new to me and I believe  I built the first  FM TV system for 24 Ghz over 35 years ago

Paul

 


From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of Clive Elliott GW4MBS via Groups.Io
Sent: 19 October 2019 09:43
To: UKMicrowaves@groups.io
Subject: [UKMicrowaves] Authority to operate on 24GHz

 

It is some years since I operated on 24GHz, out of curiosity I wonder when the requirement was dropped to obtain written authority from the Home Office to even operate a receiving station on this band?

My recollection is that to transmit you had to submit details of proposed location, NGR, PEIRP for each mode of modulation, frequency, also name, callsign & address of receiving station who presumably needed to submit a reciprocal application, oh yes & to complete a Radiation Hazard Certificate.

This made spontaneous operation very difficult. So when did things loosen up?


--
Clive GW4MBS (ex-G8ADP)
Pottering on 6m/4m/2m/70cm/23cm in a valley in IO71XW where any QSO is a triumph of optimism over geography!

No virus found in this message.
Checked by AVG - www.avg.com
Version: 2016.0.8048 / Virus Database: 4793/15886 - Release Date: 08/14/18
Internal Virus Database is out of date.


--
Paul Bicknell G8KFW   South Coast UK


Authority to operate on 24GHz

Clive Elliott GW4MBS
 

It is some years since I operated on 24GHz, out of curiosity I wonder when the requirement was dropped to obtain written authority from the Home Office to even operate a receiving station on this band?

My recollection is that to transmit you had to submit details of proposed location, NGR, PEIRP for each mode of modulation, frequency, also name, callsign & address of receiving station who presumably needed to submit a reciprocal application, oh yes & to complete a Radiation Hazard Certificate.

This made spontaneous operation very difficult. So when did things loosen up?


--
Clive GW4MBS (ex-G8ADP)
Pottering on 6m/4m/2m/70cm/23cm in a valley in IO71XW where any QSO is a triumph of optimism over geography!


Re: 23cms yagis

John Lemay
 

The aerials have arrived !

www.aerial-parts.co.uk

I wonder if it will be so easy to order and quick to deliver from Italy next
month .............

John G4ZTR

-----Original Message-----
From: John Lemay [mailto:john@...]
Sent: 17 October 2019 09:08
To: UKMicrowaves@groups.io
Subject: 23cms yagis

'Morning all

If I may be allowed a short commercial break ......

I'm importing a new batch of aerials from I0JXX, which will be here in a few
days time. They will include new models for 23cms: a 16 ele and a 36 ele.
The 16 ele is just 1.2m long and could be ideal for a quick spot of hilltop
/P work. The 36 ele is just shy of 3m long. I'm sure that these will provide
a useful and cost-effective alternative in the UK to the aerials from Wimo
(DX Shop) and Dual (W&S).

Further details will appear in my Aerial-Parts web shop shortly.

Oh, and I'm machining another batch of 23cms interdigital filters at the
moment.

That's the end of the commercial ..........

John G4ZTR


Re: UK Microwave Group 24/47/76GHz Contest on Sunday 20th October

Martyn G3UKV
 

Telford & DARS:-
Call: G3ZME/P
Locator: IO82QL83 (Brown Clee)
Band: 24 GHz (only) 0.5W, 65cm dish
Talkback: 144.390 (mainly). Also probably 'KST and Zello.
Times: 10:45-ish onwards

73 Martyn G3UKV

On 15/10/2019 12:12, John Quarmby via Groups.Io wrote:
This Sunday sees the final session of the 24/47/76GHz UKuG Contest for 2019. The weather forecast doesn't look too promising but might result in some rain scatter on 24GHz.

Please post your activity plans and I will compile a list on Saturday morning.

73

John G3XDY





Spec analyser ?

militaryoperator
 

Arinst SSA-TG R2 with tracking generator 6.2 GHz

Anyone have/tried/seen one of these babies??

Any good? rubbish? useless?


Ben G4BXD


Re: UK Microwave Group 24/47/76GHz Contest on Sunday 20th October

G4LDR
 

Providing the weather forecast for Sunday is correct (no rain) I intend to be out with 24, 47 and 76GHz.

Depending on location of other stations I will probably operate in the Stockbridge (IO91GC68) and/or Winchester (IO91JB00) and/or Petersfield (IO90MX13) areas.

24GHz 1W 30cm dish
47GHz 50mW 30cm dish
76GHz 50mW 25 cm dish/or 20cm horn

Talkback 144.390MHz +/-QSY

Times throughout.

Neil, G4LDR


Re: UK Microwave Group 24/47/76GHz Contest on Sunday 20th October

Noel G8GTZ
 

I’m planning to be out in IO91 square, exact details are weather dependant.

 

G8GTZ/P

IO91

Maybe from 10am but definitely from 1pm

24Ghz 1 watt 30cm

76GHz UKMicrowave Group loan kit

Talkback = 144.390 and KST

 

73

Noel – G8GTZ

 


Re: UK Microwave Group 24/47/76GHz Contest on Sunday 20th October

Roger Ray
 

Planned activity weather permitting.
G8CUB/P
Danbury JO01GR81
10.00 local 
24GHz 3W 30cm dish
47GHz 50mW 30cm dish
76GHz 50mW 30 cm dish
At 1.5m agl

13.00 local
Buckland IO91XX77

14.30 local
Therfield IO92XA03

Talkback: 144.390
KST

All times apx.

Roger
G8CUB