Aerials and/or Arrays

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ivorthediver
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Re: Aerials and/or Arrays

Unread post by ivorthediver »

Well Harry , If I wasn't confused before I certainly am now :oops:

sentimental parabolic, inverted ground planes being whipped by synchronicity whips siting on parabolic planes .

Its now clear to me why you and El Tel are fluent in garbled calocial whotits ...

Every man to his trade , all I have got to do now is find one I can spell correctly :oops:

However , :idea: for those who knew what you were trying hard to explain , a very important lesson ......Thank you for your efforts to explain the rudiments of your subject Harry .
"What Ever Floats your Boat"
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Little h
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Re: Aerials and/or Arrays

Unread post by Little h »

ivorthediver wrote: Mon Apr 22, 2019 6:27 pm Well Harry , If I wasn't confused before I certainly am now :oops:

sentimental parabolic, inverted ground planes being whipped by synchronicity whips siting on parabolic planes .

Its now clear to me why you and El Tel are fluent in garbled calocial whotits ...

Every man to his trade , all I have got to do now is find one I can spell correctly :oops:

However , :idea: for those who knew what you were trying hard to explain , a very important lesson ......Thank you for your efforts to explain the rudiments of your subject Harry .
.....and now, I too am completely confused Ivor.

From what I can gleen this passage "sentimental parabolic, inverted ground planes being whipped by synchronicity whips siting on parabolic planes" has been coupled together from a linked item associated with on of my posted images..... the answers to your 5 Q's were in no way couched in technical jargon, in fact I was about to re-visit my answers to ascertain whether they needed tweeking but I read your response first. See my post at:-
Re: Aerials and/or Arrays
Post by Little h » Mon Apr 22, 2019 5:03 pm
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Re: Aerials and/or Arrays

Unread post by Little h »

Little h wrote: Mon Apr 22, 2019 5:03 pm
ivorthediver wrote: Mon Apr 22, 2019 3:57 pm Less my last comment be misconstrued as sarcasm Harry , can you answer a couple of nagging questions related to your specialised subject please .

1/ whilst the ariels bars rotate how is the connection maintained :?: is it some form of wiper element what rubs over a circular contact ring :?
2/ How is it that such a powerful device can transmit a strong signal without harming any adjacent crew members :?:
3/ are the signal patterns emitted from say a whip aerial directional and if so how is their chosen path established / maintained :?:
4/ are the signals emitted from say a rotating Ariel spherical or dished as they leave the bar from which it is emitted :?:
5/ if a collection of Aerials are in operation how are they synchronised so that they don't swamp those nearest pleas

I'm sure this is all basic stuff to you and may even have been answered before but is often the source of confusion to me as clearly they cant go around the ship switching things off and on each time they wish to use them in fear of damaging another asset aboard the vessel .......and if so what happens during a RAS where other ships are in close proximity .


1/ yep slip rings or as you describe them wiper element - centimetric radars using waveguides feeding into the reflectors -
today there are also active and passive antenna systems
2/ crew members will not be anywhere near a transmitting antenna, the safe to transmit keys etc will have been removed and lodged in the Bridge or with QM if alongside. A radar antenna can still be rotating without actually transmitting.
3/ singleton whips are omnidirectional. All antenna have a polar diagram that advises the radiation pattern.
4/ this could be a particularly complicated subject; lets say the emissions will be transmitted with a particular polarisation.... and can be conical, spherical, circular, switched etc etc ... sometimes the antenna will give the clue
but modern antenna are highly sophisticated emission methodology - which is why I oft times copy the literature in support of images etc.
5/ No real need for synchronisity since they may well have significant frequency diversity/separation and there is always RAM (Radar Absorbing Material) However some antenna can and do rotate in a sychronised manner which gives a better picture below decks.


but modern antenna are highly sophisticated emission methodology -
An active electronically scanned array (AESA) is a type of phased array antenna, which is a computer-controlled array antenna in which the beam of radio waves can be electronically steered to point in different directions without moving the antenna. In the AESA, each antenna element is connected to a small solid-state transmit/receive module (TRM) under the control of a computer, which performs the functions of a transmitter and/or receiver for the antenna. This contrasts with a passive electronically scanned array (PESA), in which all the antenna elements are connected to a single transmitter and/or receiver through phase shifters under the control of the computer. AESA's main use is in radar, and these are known as active phased array radar (APAR).

The AESA is a more advanced, sophisticated, second-generation of the original PESA phased array technology. PESAs can only emit a single beam of radio waves at a single frequency at a time. The AESA can radiate multiple beams of radio waves at multiple frequencies simultaneously. AESA radars can spread their signal emissions across a wider range of frequencies, which makes them more difficult to detect over background noise, allowing ships and aircraft to radiate powerful radar signals while still remaining stealthy.

Source Wiki
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Re: Aerials and/or Arrays

Unread post by Little h »

Little h wrote: Mon Apr 22, 2019 8:19 pm
Little h wrote: Mon Apr 22, 2019 5:03 pm
ivorthediver wrote: Mon Apr 22, 2019 3:57 pm Less my last comment be misconstrued as sarcasm Harry , can you answer a couple of nagging questions related to your specialised subject please .

1/ whilst the ariels bars rotate how is the connection maintained :?: is it some form of wiper element what rubs over a circular contact ring :?

1/ yep slip rings or as you describe them wiper element - centimetric radars using waveguides feeding into the reflectors -
today there are also active and passive antenna systems


Ivor, although somewhat dated the following attachments might be of some assistance - both taken from Commons Wiki

Rotating/Rotary Joints (Radar antenna waveguide feed)

Radar_antenna_feed_waveguide.png
Waveguide_collection.jpg
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ivorthediver
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Re: Aerials and/or Arrays

Unread post by ivorthediver »

You make me laugh Harry [ not at what you find.... but how you find it :oops: ] I'm sure if I asked for some other obscure isolated detail you would come up with the info on it also ;)

You refer to "wiki' as your source of information, but you must have a wealth of knowledge with which to ask wiki for in the first place :mrgreen:

You are always either anticipating my next question or request whilst I'm still thinking about it , or bring up a post of something discussed in very broad terms in the lame hope that one of us could find it [ I refer in this case to the TV programme we were talking of whilst I was trying to unravel where I thought I might have seen it on QE2 thrust blocks ...as an instance .]

Have you fitted bugs in my iMac which listen to my verbal questions and then research them :o
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Little h
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Re: Aerials and/or Arrays

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Sandown Class MCMV

This observation relates to a feature installed on the port side aft on a selection of images of Sandown Class vessels. These images were taken in the period 2011 to 2013. The feature does not appear to be present on this class after their refits mid to end of that decade.

The feature is comprised of an unstayed polemast surmounted by a squat, tapered (top & base) cylinder shaped, sandwich dome. I became interest in this combination because a) the polemast was unstayed and that suggested that resonance/vibration may not a major consideration; and b) the cylinder domed equipment does not appear to be stabilised (or need to be stabilised). Note that the feed for the equipment within the dome is fed by a cable spiraled around the polemast and apparently secured by cableties (or similar).



Attachments & attributions

In every instance the unstayed polemast is identified by a gold arrow; and the squat, tapered (top & base) cylinder shaped, sandwich dome is identified within a red circular outline.
1 HMS Shoreham MOD 45154418 & wiki copy - Copy.jpg

HMS_Shoreham_Leading_a_Convoy_in_the_Middle_East_MOD_45154418 & wiki copy


2 HMS Shoreham (M112)_130521-N-YY107-033 wiki copy.jpg

FS Sagittaire (M650),USS Sentry (MCM_3) and the RN Sandown class HMS Shoreham (M112) 130521-N-YY107-033


3 HMS Grimsby MOD_45153354 copy - Copy.jpg
HMS_Grimsby_and_HMS_Monmouth_During_Exercise_Khanjar_Ha'ad_near_Oman._MOD_45153354 copy


4 HMS Bangor MOD_45153258 wiki comm - Copy.jpg
Royal_Navy_Sandown_Class_Mine_Countermeasures_Vessel_HMS_Bangor_Operating_near_Tobruk,_Libya_MOD_45153258 wiki commons

5 HMS Ramsey MOD_45152718 & wiki - Copy.jpg
Sandown_Class_Mine_Hunter_HMS_Ramsey_Departs_HMNB_Clyde_for_the_Middle_East_MOD_45152718 & wiki


As a consequence of not having established the purpose/function of this combined feature - I am unable to offer any idea what if anything has replaced it as various vessels emerged from their respective refits.
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Re: Aerials and/or Arrays

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NVIS (Near Vertical Incident Skywave) aerial array. - as installed on Bay Class RFA's - (revisited)


Little h wrote: Mon Sep 03, 2018 11:28 pm NVIS (Near Vertical Incident Skywave) aerial array.

A Type HF230L-N (or similar) compact HF aerial array for naval applications (frequency range of 1.6 to 30 MHz) - in this instance mounted on the RFA Lyme Bay (L3007) and not previously observed (by me).

This Datasheet (3 pages) should provide sufficient detail of the equipment featured in this post.
Note; the last two images at the bottom of page 3 show the installation on board HMS Ocean (L12).

RFA Lyme Bay L3007 DmLYHxJW4AAHilK via twitter - Copy.jpg

An example of this type of aerial array (or similar) was installed on HMS Ocean (L12) and sited on the stbd side fwd of the mainmast and immediatly aft of the funnel/exhaust uptake housing. The aerial array was also configured at an angle (45deg)(?) with the leading edge directed towards the port bow and the trailing edge towards the stbd qtr.
The following two attachments should enable comparison with the Lyme Bay (L3007) installation:-

z HMS_Ocean_(L12)_08_@chesi commons wiki - Copy.JPG
z HMS_Ocean_(L12)_19_@chesi wiki (2).JPG


It is exactly one year to the day (3rd Sept 2018) since I posted the thread opener (copied above), so it's due for a revisit. To that end I have spent some weeks viewing images of the Bay Class RFA's for any variations in the NVIS antenna array installation layout .... here are some of my observations:-

First a Cobham Type 6234-49 (or similar) HF NVIS ALE Loop Aerial array in naval use (frequency range of 2.0 to 30 MHz) - a 150W digitally tuned loop antenna designed for A) fixed frequencies, b) Frequency Hopping (H.F.) and/or c) Automatic Link Establishment (A.L.E.).

The contents of this PDF should provide sufficient detail of the NVIS antenna arrays featured in this post.
Data-sheet-6234-49.pdf



Viewed from high off the port bow looking down along the port bridge wing to the very aft extremity of same.
2 NVIS RFA Lyme Bay (L3007) Landing Ship Dock (LSD) 16,160 tonnes, Royal Navy. (14278450121) wiki 2014.jpg



Viewed from on the dockside on the port side, looking upwards at the aft bulwark of the superstructure, towards the aft extremity of the port bridge wing where the NVIS array can be clearly seen mounted atop a substantial aft projecting flange.
2 RFA Lyme Bay westside yourgibraltartv (2).jpg

This attachment is derived from an image included in the yourgibraltartv.com in an article written by YGTV Team on 19 December 2014



Viewed from off the stbd qtr looking across the ship towards the aft extremity of the port bridge wing where the NVIS array can just be discerned in this screenshot.
2 Screenshot (4767).png

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However it was not always the case that this position was occupied by an NVIS Antenna Array ..... see the following attachment that reveals a substantial whip aerial/antenna mounted in this position.


Viewed from off the stbd qtr looking across the ship towards the aft extremity of the port bridge wing where the whip aerial/antenna is easily discerned.
1 LYME BAY L3007 IMO- 9240768 Royal Fleet Auxiliary landing ship dock_(LSD(A))_23569_tons._(44371265).jpg
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Re: Aerials and/or Arrays

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NVIS (Near Vertical Incident Skywave) aerial array. - as installed on Bay Class RFA's - (revisited.1)

It is exactly one year to the day (3rd Sept 2018) since I posted the thread opener (copied above), so it's due for a revisit. To that end I have spent some weeks viewing images of the Bay Class RFA's for any variations in the NVIS antenna array installation layout .... here are some of my observations:-

Next the Type HF230L-N (or similar) compact NVIS HF aerial array for naval applications (frequency range of 1.6 to 30 MHz)

The contents of this PDF should provide sufficient detail of the NVIS antenna arrays featured in this post.


The previous post identified two versions of antenna/arrays mounted at the aft extremity of the port bridge wing atop a substantial aft projecting flange.

This post will identify that as included in the initial post the Comrod NVIS version remains an installation option (and possibly the preferred option) on this class of ship.


Viewed from off the stbd qtr looking across the ship towards the aft extremity of the port bridge wing, where the NVIS array can just be discerned in this image where loading is being performed.
3 D8DnqJAXUAEHEvf Lyme Bay on Twitter 2 Jun 2019.jpg


Viewed from a point on the aft catwalk off the stbd bridge wing looking athwarthships stbd to port.
3 NVIS D2zmDjHW0AAwlL6.jpg large 28 Mar 2019.jpg


Viewed from off the stbd qtr looking across the ship towards the aft extremity of the port bridge wing, where the NVIS array is clearly visible (mounted athwartships). However not observed previously is another NVIS antenna array mounted on an aft facing platform on the mainmast - this array appears to be mounted in a fore and aft configurated, on the ship centre line.
3 Lyme Bay Loads Hovercraft save the royal navy - Apr 2018.jpg
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There are other locations for these installations:-


Viewed from a point aft on the stbd bridge wing walkway, looking fwd
3 D1wzC-yWwAA0Nd3.jpg large Lyme Bay 16 Mar 2019.jpg


Viewed from a point fwd on the stbd bridge wing walkway, looking aft
3 NVIS Lyme Bay USNS Henry Kaiser NVIS Do5z0voXsAARjAa.jpg
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Last edited by Little h on Tue Sep 03, 2019 2:35 am, edited 1 time in total.
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Re: Aerials and/or Arrays

Unread post by Little h »

NVIS (Near Vertical Incident Skywave) aerial array. - as installed on Bay Class RFA's - (revisited.2)

It is exactly one year to the day (3rd Sept 2018) since I posted the thread opener (copied above), so it's due for a revisit. To that end I have spent some weeks viewing images of the Bay Class RFA's for any variations in the NVIS antenna array installation layout .... here are some of my observations:-

Remaining with the Type HF230L-N (or similar) compact NVIS HF aerial array for naval applications (frequency range of 1.6 to 30 MHz)

The contents of this PDF should provide sufficient detail of the NVIS antenna arrays featured in this post.

This post will identify that as for the previous post the Comrod NVIS version continues into 2019 as an installation option (and possibly the preferred option) on this class of ship.


3 EDexVkqX4AkQAUz.jpg Bournemouth Lyme Bay twitter Sept 2019 (2).jpg


3 NVIS DoLvVDEXoAA8D6Z (2).jpg


3 NVIS Lyme Bay Do5zwZyW0AAPOIM 7 Oct 2018.jpg


Note that all of these antenna array combinations are mounted at deck levels above the bridge wing walkways.
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Re: Aerials and/or Arrays

Unread post by Little h »

From Navy News March 1975

It's the individual Loops wot maketh the bigger Loop

HMS Forest Moor RN W/T Station - Harrogate District, North Yorkshire, England

Navy News March 1975 Screenshot (4802).png

Until seeing this image in the Navy News (197503) I had never seen an array of this configuration in any aerial farm, at any shore station I had frequented :oops:
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