Date
1 - 13 of 13
MRT - antenna test range
|
Noel G8GTZ
A relatively unknown feature at Eaton Manor is the 100??mt long ex chicken shed which is normally used as a practice range by the British archery team. As I was aware of the facility I have persuaded Brian G4NNS to set up an antenna test range on Saturday at MRT.
Whilst being weather proof it will have some limitations due to potential reflections but should be good for measuring antenna gain and at least the equipment and operators will remain dry.
It will be equipped to measure 3.4, 5.6, 10 and 24 GHz so bring along that odd dish you bought at a boot sale and see if it really is any better than a dipole!
We will organise a booking system on the day (not in advance by email!) so first come first served and we will appreciate help running the range so we don’t miss all the bargains or freeze to death!
See you on Saturday.
73
Noel - G8GTZ |
|
|
|
Hi Noel I'm thinking of bringing my 1m RF Ham design Dish plus triple feed for 3/6 and 9cms . It has a mast clamp for 2 inch pole , question will you have a suitable pole/support system there ? I assume I'll only need to bring the dish hardware, nothing else. Sorry to ask the obvious, I just wanted to be sure. 73 Bernie G4HWA On Wed, Nov 30, 2022 at 9:29 AM Noel G8GTZ <noel@...> wrote:
|
|
|
|
Noel G8GTZ
Yes Bernie we should be able to....
BTW Brian is not able to come to the event after all, so I'm collecting the equipment required and will receive the 2 minute training course but have not had any experience in using it so it could be interesting! Noel |
|
|
|
Hi Noel Well that’s 2 mins more than I’ll have!! I’m sure we can sort it between us See you tomorrow / Saturday 73 Bernie G4HWA On Thu, 1 Dec 2022 at 19:47, Noel G8GTZ <noel@...> wrote: Yes Bernie we should be able to.... |
|
|
|
Thanks Noel & others for running the antenna range. It was a tad cold down there.
Pleasantly surprised with my 5.7 GHz dish results .... 73 David |
|
|
|
Rob Johnston - G7MHF
Many thanks to Noel and others.
Very pleased to finally get some gold tests from my home-brew mod on the Stratex ODU feed for the 300 & 600mm Andrews 24Ghz dishes. Also pleased with the results from my penny feed 3cm conversion of a Cambium ePMP force dish |
|
|
|
g4bao
If any attendees would like to write a paragraph about the Round Table for RadCom and/or a longer piece for Scatterpoint they would be most welcome. Deadline for RadCom next Wednesday at the latest please. Happy to edit the longer one down. 73 John On Sat, 3 Dec 2022, 21:17 Rob Johnston - G7MHF, <robj@...> wrote: Many thanks to Noel and others. |
|
|
|
Robin Szemeti - G1YFG
Many thanks to Noel et al, a useful day out. Out of interest ... what was the likely accuracy achieved? My dish measured "well" ... but around 3dB lower than an ideal dish with ~60% efficiency which might be "reasonable" for the calibration at hand and I don't need to worry ... or possibly there is more to be had? On Sun, 4 Dec 2022 at 10:41, g4bao <john@...> wrote:
--
Robin Szemeti - G1YFG |
|
|
|
KENT BRITAIN
Hi Robin I run the antenna range at the Central States VHF Conference and often at Microwave Update.and North Texas Microwave Society technical parties. Probably measured close to 2000 antennas over the last 35 years.. Did you adjust the position of the feed? In most cases best gain is with the feed closer to the dish than the calculation. Cheers Kent
On Sunday, December 4, 2022 at 04:56:09 AM CST, Robin Szemeti - G1YFG via groups.io <robin@...> wrote:
Many thanks to Noel et al, a useful day out. Out of interest ... what was the likely accuracy achieved? My dish measured "well" ... but around 3dB lower than an ideal dish with ~60% efficiency which might be "reasonable" for the calibration at hand and I don't need to worry ... or possibly there is more to be had? On Sun, 4 Dec 2022 at 10:41, g4bao <john@...> wrote:
--
Robin Szemeti - G1YFG |
|
|
|
Robin Szemeti - G1YFG
My feed is kinda fixed, I suppose I should spend an afternoon with a chisel and remove the securing goop around the set-screws ... I have the same equipment as the guys at the roundtable do ... an HP451 with detector and a suitable source,so I can make my own measurements, however, what I lack is a means of absolute calibration. I have 3 pyramidial horns I can use as reference antennas, but I am uncertain of their gain. I suppose I could do some sort of 3 cornered hat calculation on those horns ... On Sun, 4 Dec 2022 at 13:30, KENT BRITAIN <WA5VJB@...> wrote:
--
Robin Szemeti - G1YFG |
|
|
|
Paul G8AQA
Not sure what frequency you were using but I have
a calibrated horn for 10GHz.
toggle quoted message
Show quoted text
Paul G8AQA On 04/12/2022 13:52, Robin Szemeti -
G1YFG via groups.io wrote:
|
|
|
|
KENT BRITAIN
I hope that is a 415! hihi While designed to run on a rechargeable 28 VDC battery, the 415 is happy with anything between 14 and 28 volts. If you slide the top cover off you see the Red and Black battery wires at the end of the edge connector. Two 9V batteries in series will run the 415 for many hours. ON the back is a 0-1V output for driving a chart recorder. But the 1000 Hz audio is there as well. I like to run that to an external amplified speaker, especially when testing VHF/UHF antennas. Lets you quickly hear any interference signals. Helix antennas are really bad about this. While designed for 23 or 13 cm. they make nice quarter wave whips at VHF! And this lets you adjust the antenna without having to look at the meter. Dish antennas do require a bit more distance. I learned this back in 1987 when optimizing the feed on my 12 foot 3 cm EME dish. Spent the whole day carefully tweaking the feed on a source 90 Meters away. Then moved the source (not the dish) left and right to measure my beam width. The beam was 1/2 meter wide at 90 Meters! I had focused it to a point! Did the next adjustment on sun noise But a dish is pretty good about ignoring reflections. Good luck with your tests, Kent Reference is nice, but do you really need it? Optimized is Optimized. Clean off the screws, you find 1 more dB, you know you are optimized and a dB better than you use to be.
On Sunday, December 4, 2022 at 07:53:12 AM CST, Robin Szemeti - G1YFG via groups.io <robin@...> wrote:
My feed is kinda fixed, I suppose I should spend an afternoon with a chisel and remove the securing goop around the set-screws ... I have the same equipment as the guys at the roundtable do ... an HP451 with detector and a suitable source,so I can make my own measurements, however, what I lack is a means of absolute calibration. I have 3 pyramidial horns I can use as reference antennas, but I am uncertain of their gain. I suppose I could do some sort of 3 cornered hat calculation on those horns ... On Sun, 4 Dec 2022 at 13:30, KENT BRITAIN <WA5VJB@...> wrote:
--
Robin Szemeti - G1YFG |
|
|
|
paul firmstone GW0MDQ
hi Noel,
Thank you for testing my Flann horn against the Radar Horn, I had no way of really compairing the antennas before the test on Saturday. Cheers.. Paul GW0MDQ |
|
|