Half Wave, 5/8'S WAVE VERTICAL ANTENNA HELP!

[kellyjbrian]

Hey Guys,
I have a 600 watt tx and I'm looking for something on the lines of (shown below) Half Wave, 5/8'S WAVE VERTICAL ANTENNA that can handle 600 watts.

http://www.aareff.com/5-8ant.htm


I dont have alot of space on the mast I am using and I'd be delighted if someone could help me in locating something on the lines of whats shown in the above link.

Thanks everyone!

 

[RealityCheckr]

It has been a while since I looked at the rules, but ISTR your vertical radiation cannot be greater than the horizontal.

Can anyone confirm this is still true?

Hey Guys,
I have a 600 watt tx and I'm looking for something on the lines of (shown below) Half Wave, 5/8'S WAVE VERTICAL ANTENNA that can handle 600 watts.

http://www.aareff.com/5-8ant.htm


I dont have alot of space on the mast I am using and I'd be delighted if someone could help me in locating something on the lines of whats shown in the above link.

Thanks everyone!

 

[mp3RadioGuy]

Here's a nice FM antenna that will handle more than 600 watts.

http://fmbroadcastantenna.com/

 

[DanStrassberg]

Here's a nice FM antenna that will handle more than 600 watts.
http://fmbroadcastantenna.com/

Does the FCC do type-acceptance on FM transmitting antennas? If so, do these and the other 5/8-wave FM antenna that someone else mentioned in an earlier post in this thread have type acceptance?

 

[ChiefEngineer]

Here's a nice FM antenna that will handle more than 600 watts.
http://fmbroadcastantenna.com/

Does the FCC do type-acceptance on FM transmitting antennas? If so, do these and the other 5/8-wave FM antenna that someone else mentioned in an earlier post in this thread have type acceptance?

Your transmitting equipment is REQUIRED to be type accepted. In the forms for new applications the form requires you to confirm your TRANSMITTER is type accepted.


There is a line item in Engineering to indicated the 3 letter manufacturer and the model number of the antenna and all antennas recognized are listed. The dominator is not.

It is a good antenna , no doubt, however, it's gain figures are not certified so the gain you get is the difference of the circular gain being all vertical.

 

[BobOnTheJob]

It has been a while since I looked at the rules, but ISTR your vertical radiation cannot be greater than the horizontal.

Can anyone confirm this is still true?

Hey Guys,
I have a 600 watt tx and I'm looking for something on the lines of (shown below) Half Wave, 5/8'S WAVE VERTICAL ANTENNA that can handle 600 watts.

http://www.aareff.com/5-8ant.htm


I dont have alot of space on the mast I am using and I'd be delighted if someone could help me in locating something on the lines of whats shown in the above link.

Thanks everyone!

Generally true, but where a channel 6 must be protected, Vertical only FM's are very common. Central Indiana has too many to count...

 

[greg.hahn]

As a public service to our aspiring young broadcasters reading this site, I'd like to point out that the above-referenced site, broadcastantenna.com, has a link that is a huge distortion of reality: http://fmbroadcastantenna.com/polarizationinfo.html

Despite the nonsense that this link states, vertically polarized antennas are not superior to circularly polarized antennas. One quote:

From an engineering rationale, the polarization used for transmission should be chosen so as to best match the polarization of the receive antennas used for car and home stereos. One may therefore ask " How many car or home FM receivers have a circularly polarized receive antenna? ". The answer is – zero to none. If one asks " How many have a horizontally polarized receive antenna ? "; the answer is - a tiny percentage. If one asks " How many have a vertically polarized receive antenna? "; the answer is - most cars, the bulk of today’s market, have a vertical whip receive antenna. Most home FM receivers have a wire hanging out the back. The conclusion to be drawn from this is that: for optimum match between the polarization of transmitted and received signals in order to provide optimum area coverage, vertical polarization is best.

The implication here is that the receive antennas must also be circularly polarized in order to benefit from the circularly polarized transmitting antennas.

Well gee, then aren't broadcasters stupid for not using the best antennas possible?


Corollary: Any company that prints sales literature this deceptive cannot be trusted. Period.

 

[Play Freebird]

I would strongly agree that circular polarization is superior to vertical-only -- but if transmitter power and/or tower space are limited, or contour protection requirements demand use of a log-periodic antenna, it may be necessary to stay with linear polarization. My experience with FM translators has shown that vertical produces noticeably better results than horizontal.

Here the link to the BBC report referenced in that sales piece. The conclusion: Go with mixed (circular) if you can afford it:

http://downloads.bbc.co.uk/rd/pubs/reports/1986-13.pdf

However, it's interesting to note that almost all of the Eureka-147 DAB transmit antennas installed in the past several years in central Europe are vertical-only. This may be beneficial in networks where synchronous digital boosters are deployed.

 

[ChiefEngineer]

I received a Pm about "Type Acceptance" and verified through S and T as well as this line from a 302 DTV that type acceptance still exists.

In order to qualify as a "main studio," the proposed location must be equipped with type-accepted equipment and capable of originating programming at any time.

If Type Accepted or "Certificated" (it's listed on the Commission's site in at least 5 places) the Dominator is not Certificated, Certified, or Type Accepted.

It would be possible under the new regulations to have the Dominator "listed" if they applied and supplied the technical data to back their claims. This is why they have a station in Africa on the front page of their website.

I have called 5 stations who were "listed" as operating with the Dominator and claimed it worked better than the old circular antenna and none of them ever existed in the US. Phone number disconnected, answering machine that never answered with a lvie person, etc. If anyone used it they were unwilling to claim it.

 

[Shockwave]

As a public service to our aspiring young broadcasters reading this site, I'd like to point out that the above-referenced site, broadcastantenna.com, has a link that is a huge distortion of reality: http://fmbroadcastantenna.com/polarizationinfo.html

Despite the nonsense that this link states, vertically polarized antennas are not superior to circularly polarized antennas. One quote:

From an engineering rationale, the polarization used for transmission should be chosen so as to best match the polarization of the receive antennas used for car and home stereos. One may therefore ask " How many car or home FM receivers have a circularly polarized receive antenna? ". The answer is – zero to none. If one asks " How many have a horizontally polarized receive antenna ? "; the answer is - a tiny percentage. If one asks " How many have a vertically polarized receive antenna? "; the answer is - most cars, the bulk of today’s market, have a vertical whip receive antenna. Most home FM receivers have a wire hanging out the back. The conclusion to be drawn from this is that: for optimum match between the polarization of transmitted and received signals in order to provide optimum area coverage, vertical polarization is best.

The implication here is that the receive antennas must also be circularly polarized in order to benefit from the circularly polarized transmitting antennas.

Well gee, then aren't broadcasters stupid for not using the best antennas possible?


Corollary: Any company that prints sales literature this deceptive cannot be trusted. Period.

In an effort to maintain accuracy I'd like to point out a few things about the polarization page on http://fmbroadcastantenna.com/ and comments here. It's not a case of broadcasters being stupid for not using the best antennas. I think we can all agree that the circularly polarized antenna is far from the most efficient radiator at -3 dbd. It's more that the FCC has created a set of rules that give the circular polarized antenna some benefits in the USA it would not otherwise have.

By authorizing equal ERP in both planes the FCC made an attempt to patch the mistake of originally authorizing the band for horizontal only. Horizontal polarization proved disastrous for any type of portable reception. This is what made CP the standard in the USA. Had this mistake never taken place back in the 1940's broadcasters would probably be looking at a very different selection of FM antennas today.

I took the time to read the polarization information in the link and it's referenced sources. The BBC report is especially interesting and lends a good deal of credibility to the idea of vertical only polarization in FM band II. In the link http://downloads.bbc.co.uk/rd/pubs/reports/1986-13.pdf the BBC states " In the absence of interference, vertical polarization is undoubtedly the best choice for FM band II broadcasting. Not only is it the optimum choice for low receiving antenna heights, cars, and portables, but for fixed installations VP works equally as well".

Surprisingly, reports from the UK on the circularly polarized antenna do not claim the antennas main benefit is in the area of multipath distortion as one would expect. The BBC claims the primary advantage that CP or HP offers is the ability to use directional horizontal receiving antennas at fixed locations to reject signals from unwanted directions. Multipath distortion did not prove to be the "disastrous" problem with VP in the UK as we have been told in the US.

If CP had a significant improvement on multipath, don't you think we would have seen it's use expanded to the nearly 5 MHz. wide transmission of TV to reduce video ghosting? Working with RF all of my life and dealing with problems such as these, I've often question this. Along with the fact that the only other examples of CP use I find outside of FM are in situations where it is not possible to obtain a fixed polarization on the desired signal. Such as in satellite communications.

Other countries are reporting similar results as the BBC in the UK. They are opting for vertical polarization in all new installations. Avoiding horizontal polarization altogether. Circular polarization seems to be considered only at older facilities that need to maintain compatibility with existing directional horizontal reception antennas. These facilities were originally HP and had to be updated to add VP. Of course those few horizontal Yagi's can easily be turned on their side for vertical reception.

I also found the design of this Dominator antenna intriguing. looking into this leads me to believe it goes beyond just focusing all of your power in the vertical plane. The antenna has some reasonable gain. It seems the basic design of the Dominator has been around since the late 1930's in amateur radio. There is a patent on file at the PTO with test reports conducted by Avanti Research and Development. They indicated they were able to achieve a gain of 2.7 dbd in a 3/4 wave model by adjusting the angle and dimensions of the cone.

That's not too far off from the Norwalk Electronics claim of 5.14 dbi or 3 dbd in the larger .82 wave Dominator design. It would be nice if the FCC updated regulations pertaining to antenna requirements. Allowing us wider access to the VP option. Then again since the FCC sold amateur spectrum to UPS and VHF TV spectrum to the highest bidder.....what are we to expect? Anyone know where that money went? I was waiting for a rebate on my portion of the public airwaves that were sold to private companies. LOL.

 

[rfry]

I think we can all agree that the circularly polarized antenna is far from the most efficient radiator at -3 dbd.

Note that while c-pol antennas have 3 dB less peak gain than if they were linearly polarized, the effective radiated power can be made the same for the two configurations simply by increasing the input power applied to the antenna by 3 dB. This is permitted/required by the FCC for FM and TV stations using c-pol transmit antennas.

Surprisingly, reports from the UK on the circularly polarized antenna do not claim the antennas main benefit is in the area of multipath distortion as one would expect. The BBC claims the primary advantage that CP or HP offers is the ability to use directional horizontal receiving antennas at fixed locations to reject signals from unwanted directions.

As you noted later in your post, v-pol directional receiving antennas also are available.

If CP had a significant improvement on multipath, don't you think we would have seen it's use expanded to the nearly 5 MHz. wide transmission of TV to reduce video ghosting?

The real benefit of using c-pol requires the use of a c-pol receive antenna. Reflections along the propagation path change their c-pol "sense" (direction of rotation) to the opposite of the direct wave, which reflections are then rejected by the receive antenna.

An analog channel 7 TV station in Chicago used a c-pol antenna transmitting from Sears Tower, and there was a marked reduction in "ghosting" seen on a mobile TV set using a c-pol receive antenna when driving around in the Loop. In some locations the received signal went from unwatchable in h-pol transmission/reception to very good quality using c-pol.

True circular polarization requires equal fields at all polarization angles, not just H & V.

//

 

[Shockwave]

I think we can all agree that the circularly polarized antenna is far from the most efficient radiator at -3 dbd.

Note that while c-pol antennas have 3 dB less peak gain than if they were linearly polarized, the effective radiated power can be made the same for the two configurations simply by increasing the input power applied to the antenna by 3 dB. This is permitted/required by the FCC for FM and TV stations using c-pol transmit antennas.

Surprisingly, reports from the UK on the circularly polarized antenna do not claim the antennas main benefit is in the area of multipath distortion as one would expect. The BBC claims the primary advantage that CP or HP offers is the ability to use directional horizontal receiving antennas at fixed locations to reject signals from unwanted directions.

As you noted later in your post, v-pol directional receiving antennas also are available.

If CP had a significant improvement on multipath, don't you think we would have seen it's use expanded to the nearly 5 MHz. wide transmission of TV to reduce video ghosting?

The real benefit of using c-pol requires the use of a c-pol receive antenna. Reflections along the propagation path change their c-pol "sense" (direction of rotation) to the opposite of the direct wave, which reflections are then rejected by the receive antenna.

An analog channel 7 TV station in Chicago used a c-pol antenna transmitting from Sears Tower, and there was a marked reduction in "ghosting" seen on a mobile TV set using a c-pol receive antenna when driving around in the Loop. In some locations the received signal went from unwatchable in h-pol transmission/reception to very good quality using c-pol.

True circular polarization requires equal fields at all polarization angles, not just H & V.

//

The FCC allowing the 3 db increase in TPO when using CP is what made it the standard in the USA. I’m in complete agreement that this loss in gain can be compensated for by doubling TPO or using twice as many bays. This is great if your station has deep pockets. From an economical standpoint this can be hard to justify for the tradeoff in multipath distortion offered in return.

With respect to requiring CP on both the TX and RX ends to obtain real benefits, absolutely what I expected. While Greg doesn’t seem to agree here, the reality is half of the TX power is essentially wasted in CP unless the RX end uses CP also. The receiver antenna mostly responds to energy in one polarization, unable to benefit from the TX being at all polar angles.

Thank you for pointing out TV 7 in Chicago used CP. I had forgotten about the Turnstile and Batwing. My question is why are they not more popular then dipole arrays or slot antennas in TV broadcast? Is it because the benefits are minimal without CP on the receiver, or the enormous TPO it would require for the video signal?

I had the chance to design a directional CP antenna for the 440 UHF band years ago. Basically two Yagi’s on the same boom. One vertical and one horizontal. The key to forming true circular polarization simply involved feeding one driven element 90 degrees out of phase from the other. Changing the element with the delay line changed the polarization from left hand to right hand.

 

[davideduardo]

Other countries are reporting similar results as the BBC in the UK. They are opting for vertical polarization in all new installations. Avoiding horizontal polarization altogether. Circular polarization seems to be considered only at older facilities that need to maintain compatibility with existing directional horizontal reception antennas.

In 1966 I put the first FM in the country (and for about 1000 miles around) on the air in Ecuador. Since there were no regulations, I was able to pretty much write my own technical standards.

Experimenting with antennas we made ourselves, I discovered that going to only vertical polarization reduced multipath considerably. My site was on the side of a mountain about 1000 meters above Quito, but it bounced off numerous other hills and mountains surrounding the city (which itself was at 10,000 feet). Horizontal was simply unbearable, while vertical made considerable difference in reception, even in static locations. In part, this may have contributed to the station being profitable in its second year on the air.

 

[Shockwave]

Other countries are reporting similar results as the BBC in the UK. They are opting for vertical polarization in all new installations. Avoiding horizontal polarization altogether. Circular polarization seems to be considered only at older facilities that need to maintain compatibility with existing directional horizontal reception antennas.

In 1966 I put the first FM in the country (and for about 1000 miles around) on the air in Ecuador. Since there were no regulations, I was able to pretty much write my own technical standards.

Experimenting with antennas we made ourselves, I discovered that going to only vertical polarization reduced multipath considerably. My site was on the side of a mountain about 1000 meters above Quito, but it bounced off numerous other hills and mountains surrounding the city (which itself was at 10,000 feet). Horizontal was simply unbearable, while vertical made considerable difference in reception, even in static locations. In part, this may have contributed to the station being profitable in its second year on the air.

Not enough FM engineers have first hand experience with vertical polarization in the US. Another great advantage with VP is the RF levels on the ground under the tower are substantially less then either CP or HP. The antenna does not need to be nearly as high to provide safe exposure levels to people and equipment below. End fire problems are non-existent.

Since half the number of bays can be used with VP, the need for null fill and beam tilt are not required as often. The bandwidth of any given linear polarized system will be noticeably wider then a CP array of equal gain. Lets not overlook the efficient use of tower space that VP offers too.

 

[greg.hahn]

Another great advantage with VP is the RF levels on the ground under the tower are substantially less then either CP or HP. The antenna does not need to be nearly as high to provide safe exposure levels to people and equipment below. End fire problems are non-existent.

Even better than half-wave CP spacing? That is typically what a professional broadcaster does to minimize downward radiation, rather than putting up a vertical antenna.

Since half the number of bays can be used with VP, the need for null fill and beam tilt are not required as often. The bandwidth of any given linear polarized system will be noticeably wider then a CP array of equal gain. Lets not overlook the efficient use of tower space that VP offers too.

The bandwidth of a typical rototiller CP is wide enough to drive a truck through. In the typical installation, why would you want any more?

I fully understand that a vertical antenna will provide adequate coverage for the majority of listeners, but those with horizontally polarized receiver antennas will suffer poor reception. (Most outdoor antennas, most dipole antenna included with home receivers, some automotive antennas.)

My point is that the author of the paper on the site knows that, but distorts it. And it even makes the claim that CP polarization is not received well on vertical or horizontal receive antennas, which is ridiculous. The point of us using CP antennas is superior reception under most circumstances.

 

[Tom Wells]

I recall the night WLS TV went to CP in 1974 or 1975. They switched over at 10PM just before the local newcast with
the hopeful promise," And now with only ONE Fahey Flynn, the 10 O'Clock news."
In NW Indiana, the picture DID improve on TVs with horizontal polarized antennas.

 

[rfry]

Another great advantage with VP is the RF levels on the ground under the tower are substantially less then either CP or HP.

That depends on the design of the radiating element(s). The radiation patterns of modern, c-pol FM broadcast transmit antenna elements available from Dielectric Communications, ERI and Jampro have (theoretically) zero free-space field at -90 degrees elevation, directly under them. "Ring-stub" type elements do have substantially more radiation directly below them than v-pol elements alone, however using 1/2-wave spacing of the elements reduces that to zero (in theory).

However the radiation patterns of all side-mounted FM transmit antennas of this type (even v-pol only) are distorted by the adjacent mounting structure, and their resulting patterns can be quite unpredictable. V-pol radiation is more affected by this than is h-pol.

Paper 6 at http://rfry.org goes into some detail about this.

Paper 10 there includes the theoretical patterns for all four of the c-pol element types mentioned above.

The bandwidth of any given linear polarized system will be noticeably wider then a CP array of equal gain.

Bandwidth is mostly a function of the element design, not its polarization. C-pol antennas from the three OEMs above have been used to multiplex several FM stations into one array with spacings of 6 MHz and more.

//

 

[Shockwave]

Another great advantage with VP is the RF levels on the ground under the tower are substantially less then either CP or HP. The antenna does not need to be nearly as high to provide safe exposure levels to people and equipment below. End fire problems are non-existent.

Even better than half-wave CP spacing? That is typically what a professional broadcaster does to minimize downward radiation, rather than putting up a vertical antenna.

Since half the number of bays can be used with VP, the need for null fill and beam tilt are not required as often. The bandwidth of any given linear polarized system will be noticeably wider then a CP array of equal gain. Lets not overlook the efficient use of tower space that VP offers too.

The bandwidth of a typical rototiller CP is wide enough to drive a truck through. In the typical installation, why would you want any more?

I fully understand that a vertical antenna will provide adequate coverage for the majority of listeners, but those with horizontally polarized receiver antennas will suffer poor reception. (Most outdoor antennas, most dipole antenna included with home receivers, some automotive antennas.)

My point is that the author of the paper on the site knows that, but distorts it. And it even makes the claim that CP polarization is not received well on vertical or horizontal receive antennas, which is ridiculous. The point of us using CP antennas is superior reception under most circumstances.

1) Downward radiation: Radiation levels at the tower base with VP are substancially lower then with CP even with half wave spacing. Additionally, you don't have to compromise radiation efficiency by using half wave spacing to obtain safe exposure levels. Think about it. All forms of horizontal antennas including CP will inherently radiate energy upwards and downwards due to the plane the radiation element is in. With VP there is no radiation surface area on the array that is parallel to ground. This produces very different RF field strenghts below the tower. VP provides a deep null in RF at the tower base. The exact place where we would find an RF hot spot with CP or HP.

2) Bandwidth: At +/-200 KHz. bandwidth on the Rototiller, this implies a fairly small truck is being driven. The slightest change in either inductive or capacitive reactance in these CP sytems can cause large variations in VSWR. VP typically offers several times this bandwidth because their elements have a lower Q. Extra bandwidth is desirable for many reasons. Including less impact on VSWR when side mounted and easier to tune. Increased resistance to detuning due to adverse weather conditions. Possibly eliminating the need for radomes or deicers.

3) Vertical coverage: Vertical polarization actualy provides excellent coverage to the majority of FM listeners. Granted HP only listeners will experience a signal drop. However, this mostly pertains to the small percentage of roof mounted antennas in use. Just the fact that these recievers have an outdoor antenna connected will usually compensate for the losses in cross polarazation. Most high end recievers don't use a 300 ohm connection anymore and the included folded dipole has become less popular. Todays recievers often have an F connector and they supply you with a 1/4 wave peice of wire with the F plug on it. This requires no matching transformer and offers omni reception.

4) Author of paper: What the author of the paper says in a nutshell is "the polarization used for transmission should be chosen so as to best match the polarization of the receive antennas used". He didn't say CP is not recieved well on vertical or horizontal antennas. He simply pointed out that maximum signal transfer takes place when both the transmit and recieve antenna polarization match. This is not ridiculous, it's common knowlegde.

 

[rfry]

Think about it. All forms of horizontal antennas including CP will inherently radiate energy upwards and downwards due to the plane the radiation element is in. With VP there is no radiation surface area on the array that is parallel to ground.

Note that the free-space radiation patterns from the c-pol radiator elements of Dielectric Comms, ERI and Jampro have the same elevation pattern shape as that of a vertical dipole. Radiation from different parts of each of these c-pol elements is out of phase at +/-90 degrees elevation, and cancels. Please review the patterns for them in paper 6 at http://rfry.org.

For further confirmation see http://dielectric.com/broadcast/catalogs/FMCatalog2004.pdf . Page 39 there shows the elevation patterns for full and 1/2-wave spaced arrays, and they all show zero radiation at -90 degrees. ERI and Jampro literature shows about the same.

Bandwidth: At +/-200 KHz. bandwidth on the Rototiller, this implies a fairly small truck is being driven. The slightest change in either inductive or capacitive reactance in these CP sytems can cause large variations in VSWR.

Sorry, but that information is incorrect. As I mentioned earlier, some rototiller designs are used to multiplex several FM stations into one antenna, where they can be spaced 6 MHz or more apart.

Also see page 10 of the Dielectric catalog linked above. Notice in the "bullets" under the picture for the DCR-Q that it is specified to have 16 MHz of r-f bandwidth. That is a c-pol design.

//

 

[Shockwave]

Think about it. All forms of horizontal antennas including CP will inherently radiate energy upwards and downwards due to the plane the radiation element is in. With VP there is no radiation surface area on the array that is parallel to ground.

Note that the free-space radiation patterns from the c-pol radiator elements of Dielectric Comms, ERI and Jampro have the same elevation pattern shape as that of a vertical dipole. Radiation from different parts of each of these c-pol elements is out of phase at +/-90 degrees elevation, and cancels. Please review the patterns for them in paper 6 at http://rfry.org.

For further confirmation see http://dielectric.com/broadcast/catalogs/FMCatalog2004.pdf . Page 39 there shows the elevation patterns for full and 1/2-wave spaced arrays, and they all show zero radiation at -90 degrees. ERI and Jampro literature shows about the same.

Bandwidth: At +/-200 KHz. bandwidth on the Rototiller, this implies a fairly small truck is being driven. The slightest change in either inductive or capacitive reactance in these CP sytems can cause large variations in VSWR.

Sorry, but that information is incorrect. As I mentioned earlier, some rototiller designs are used to multiplex several FM stations into one antenna, where they can be spaced 6 MHz or more apart.

Also see page 10 of the Dielectric catalog linked above. Notice in the "bullets" under the picture for the DCR-Q that it is specified to have 16 MHz of r-f bandwidth. That is a c-pol design.

//

It all comes down to cost. Spend enough money and you can obtain good gain, cancel downward radiation and expand bandwidth with CP. Richard did teach me something with the canceling of downward radiation in CP. Thank you! I still suspect it's lower in VP without the need to cancel.

The CP models you mention with extended bandwidth are specially designed to do be broadbanded. Linear polarization inherently has more bandwidth then CP due to the configuration of their elements. Many CP bays and some models of the Rototiller do have as little as +/-200 KHz. At VHF, the basic VP dipole has a bandwidth measured in MHz. Broadband VP antennas can easily cover the entire band.

My main point here was the goals of high gain, wide bandwidth, and reduced downward radiation are all easier to achieve with VP and far less expensive then CP. If the station has the finances to purchase the CP system, room on the tower to install the bays, and wants to pay the light bill for the added TPO required, CP has some minimal benefits. Bottom line is you can buy more coverage area at a fraction of the cost using VP.