Jump to content

Sharkfin Antenna options


ProSound

Recommended Posts

Based upon my research it seems all sharkfins are created equal so would there be anything wrong with this pair from Audio Technica for $286.00

http://www.bhphotovideo.com/c/product/352354-REG/Audio_Technica_ATW_A49_ATW_A49_UHF_LPDA.html

As compared to the PSC Version which are $311.00 for the pair?

http://www.bhphotovideo.com/c/product/330710-REG/PSC_FPSC0044_UHF_Log_Periodic_Antenna.html

Thanks

Link to comment
Share on other sites

Agree with Wolf.  A lot of math and voodoo go into antenna design.  Check out the spacing of the elements on the 2 antennas shows, they're different.  Also, other antennas have more elements that increase both the gain and frequency range.  And then there is the design of the cable and mounting connectors.  My Zaxcom antennas perform the best electronically but have the worst mounting options (ie, none) and the bnc connector is not a right angle and is not strain reliefed.  Other LP antennas I've tried do not give as much gain but have better mechanical designs.

Billy

No they are not equal, very similar yes, at short range perform identical yes, but so does a paperclip. I have posted a LONG and tedious writeup sometime in the last years... go search  wolf ( our ugly green ones are $ 175 EACH)

Link to comment
Share on other sites

" Would sandwiching a sharkfin between two pieces of plexi (for protection and strength) affect the performance of it? "

antenna "receiving" performance?? probably not,  but it would add weight and bulk that could present issues... buy a different one, and consider the skeletal versions for better wind performance...

Link to comment
Share on other sites

  • 2 months later...

NO, redesign is not warranted by the low sales numbers. I dont recommend sawing off the front element esp. since the connector is there.  :-)

still at

http://wolfvid.com/datasheets/Antenna_UHF_flat_panel.pdf

here an older writeup which I might have posted before ( I wonder if anybody reads posts longer than 3 lines?)

We recommend for general use the WSV green flat panel Antenna. This is a high gain flat log periodic antenna. All antennae are good at short range. Where they differ is in the extreme end of range. In a bad multipath environment at short range, any directional antenna is better than a non-directional one. The omni rubber ducks are non-directional or omni directional. So if you can, use a directional antenna.

The gray CIT ultra has a little more gain than the other three we tested: WSV aluminum, Lectrosonics flat panel, PSC flat panel and WSV green flat panel. 

In normal transmitting distances with a decent signal, there is no difference between these antennas. At low signal strength there are very subtle but discernable differences between the antennae and between cable types used. 50W black Belden cable is preferred. Generally, the CIT (gray) antenna is a little more sensitive to low level signals at high and low frequencies. This shows up on the DX-404 tuner as one or two additional LEDs lighting up. The WSV (green) antenna seems a little more sensitive to reflections from objects within 3 ft. of antenna. The Lectrosonics (black) and WSV (green) seem to be very similar otherwise.

What this means in practical terms is: if you’re receiving a small transmitter at the end of a 100 yard football field, the CIT antenna would be good for 100 yards, whereas the others will be good for 98 yards.

Again, this is splitting hairs at the extreme far end of the receiving range. The new DX-404 tuner seems to switch antennae without any color phase shifts in the picture.

Relative position (where you put the antenna) is much more important than the exact direction you point it or the brand of antenna.  So move your antennae 6" to left or right or up and down for best pictures.  This demonstrates the radical effect multipath has on the signal.  The reason the picture is bad 6" away from the original position is only multipath.  So when you see a picture get bad, and then good, when one end of the transmission chain is moving, you are observing the different patterns of multipath.  Therefore you should continuously experiment with better positions.

The CIT antenna is very bad below channel 14. Our WSV Log Periodic is not as sensitive to accurate pointing.  It has a wider pattern. With low signal strength use the side lobes (30° off center) rather than on axis.  CIT is very sensitive to horizontal - vertical position.  For best results, it has to be perfectly parallel (the same spatial plane) with the modulator’s antenna, especially at the higher channels. (This is the price you pay for the high gain.)  WSV Log Periodic has slightly less gain than others but is much easier to point.  Antennae in order of gain: CIT Ultra Antenna, Lectrosonics, PSC, and WSV. Remember to experiment with antennae positions all the time.  The best solution is four antennae spaced by 3 ft. for the diversity receiver of course.

Look at the artwork below and think a little. If the transmitter is vertical, the receiver also has to be vertical. Note the difference in vertical or horizontal radiation pattern. This is called phase of a transmitter signal.

Link to comment
Share on other sites

I have several pairs including the Lectrosonics ALP700, which were great but you have to replace the pieces you break off. I now use the cut out Lectros. I love that the wind doesn't catch them. The wind used to be a real problem with a horizontal spread mast.

I also have a pair of the Audio Technicas. I was working on an exterior set that was a 6 acre scrap yard. We positioned them on top of a portable building and they stayed for weeks out in the elements. My thought was if they rusted I would just toss them. Still have them and no rust. We had rain 20 out of 28 days so taking the carts out of the truck was just not smart. We used those Audio Technicas for the entire time we were at that location.

Link to comment
Share on other sites

Lectro sharkfins are excellent and with versatile mounting options.

There's one that is lighter and stands better against the wind because of the vent perforations (ALP620, it's what I use now plus Lectro SNA600 dipoles)

Get a good low loss 50 ohm cable for more than a couple of meters

Link to comment
Share on other sites

Hi Brad,

The original elements for the ALP700 were made of hardened aluminum for some dumb reason with a thread (break point) right at the insertion point of the mast. They were "designed" to break if you dropped them. The later replacement elements are a softer aluminum with a ferrule that puts the bend point up on the smooth part of the rod. The replacements bend and can be straightened. The sharkfin LPDA ALP600 version works as well as the mast and element ALP700 and is many, many times more rugged. The only drawback was the wind load. The weird ventilation hole pattern pretty much fixed that. Therefore,we dropped the original LPDA, the ALP700, even though it looked much cooler.

Best,

LarryF

I have several pairs including the Lectrosonics ALP700, which were great but you have to replace the pieces you break off. I now use the cut out Lectros. I love that the wind doesn't catch them. The wind used to be a real problem with a horizontal spread mast.

Link to comment
Share on other sites

Thanks Larry...It's good to see you here.

Could you or someone else clear up something for me? I talked to Bruce a few years ago when I was using a horizontal antenna mast with block 21 T1 transmitters and block 22 recievers. He suggested a vertical spead would better isolate any possible interference between the trasmit and recieve. I have switched to this concept and really like how much better I get through doorways quickly. Seems to work just fine. If I need one antenna closer to set I will remote one, but most of the time it work fine one on top of the other with about a 18" between.

Brad

Link to comment
Share on other sites

Hi Brad,

See this data sheet and look at the graph of the vertical pattern.

http://www.lectrosonics.com/images/TD-sheets/alpseriestd.pdf

By stacking the antennas vertically, you are operating in the 90 degree area where the antennas have a null, i.e., they don't see one another. You can probably use less than 18" if you wanted to but that separation is very good.

Best Regards,

Larry Fisher

Lectrosonics

Thanks Larry...It's good to see you here.

Could you or someone else clear up something for me? I talked to Bruce a few years ago when I was using a horizontal antenna mast with block 21 T1 transmitters and block 22 recievers. He suggested a vertical spead would better isolate any possible interference between the trasmit and recieve. I have switched to this concept and really like how much better I get through doorways quickly. Seems to work just fine. If I need one antenna closer to set I will remote one, but most of the time it work fine one on top of the other with about a 18" between.

Brad

Link to comment
Share on other sites

Mostly because you want to get the antenna away from the mounting post (which is a big ground).  It's harder to do that with a vertical mount.  Another common scenario is to use a 'T' bar mount (like the Manfrotto Stereo Mic Bar) and mount on of the antennas upside down.

Best,

Billy Sarokin

Link to comment
Share on other sites

  • 3 months later...

Using plastic to support the antennas still presents a problem. The shield of the coax cables attached to the antennas is also a ground, and the cables are usually run along the mast supporting the antennas, so using plastic instead of metal would provide little advantage. The stacked antennas could be supported on a short metal horizontal struts attached at the rear to space them away from the vertical metal mast. The coax cables can be run along the supporting strut to the mast, and then downward.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...