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Author Topic: "flagpole" vertical height  (Read 22021 times)

K4EZD

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"flagpole" vertical height
« on: October 24, 2014, 04:07:42 PM »

I live in a HOA area where antennas are not permitted but I currently have a vertical in the backyard that resembles a flagpole enough to avoid any issues so far.  I have the DX Engineering radial plate and 16 radials with the DX Engineering fold over mount.  So far I have 19 feet of aluminum tubing feeding into a 4:1 unun and direct burry coax.  I know that they have a 24 foot vertical for 10 – 40 meters but so far I have assembled only the 19 feet to avoid drawing too much attention.  With my autotuner and my Icom 7410 running barefoot (100 watts) I have been able to tune with acceptable SWR on all bands 10 – 40.  I have no test equipment to speak of but want to know if extending the vertical up to 24 feet would noticeably help.  I work mostly digital but some SSB.  Any helpful opinion would be appreciated.
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N4UM

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RE: "flagpole" vertical height
« Reply #1 on: October 24, 2014, 05:34:55 PM »

I use a 23 foot homebrew flagpole for 40 thru 10 meters fed wih "BuryFlex" and operate mostly digital with about 20% on CW.  Going from 19 to 24 feet might help you a bit on 40 but I doubt if it would do anything very much for the other bands.  The biggest improvement you could make would probably be increasing your number of radials from 16 to 32 or perhaps even to as many as 50 or more.
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KH6AQ

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RE: "flagpole" vertical height
« Reply #2 on: October 28, 2014, 07:16:46 AM »

At 7.15 MHz the radiation resistance of the 19' vertical is 9 ohms while the 24' is 15 ohms. Given estimated ground loss of 15 ohms and tuner loss of 5 ohms the radiation efficiencies are 31 and 43 percent. The difference is 1.4 dB. With enough radials the ground loss can be under 5 ohms yielding almost 2 dB additional gain on the 19' vertical. The downside of additional radials is that the VSWR will increase and line loss will increase.

One improvement for 7 MHz is to remove the 4:1 unun. That lowers the VSWR and line loss.

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W3WN

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RE: "flagpole" vertical height
« Reply #3 on: October 29, 2014, 07:30:51 AM »

I live in a HOA area where antennas are not permitted but I currently have a vertical in the backyard that resembles a flagpole enough to avoid any issues so far.  I have the DX Engineering radial plate and 16 radials with the DX Engineering fold over mount.  So far I have 19 feet of aluminum tubing feeding into a 4:1 unun and direct burry coax.  I know that they have a 24 foot vertical for 10 – 40 meters but so far I have assembled only the 19 feet to avoid drawing too much attention.  With my autotuner and my Icom 7410 running barefoot (100 watts) I have been able to tune with acceptable SWR on all bands 10 – 40.  I have no test equipment to speak of but want to know if extending the vertical up to 24 feet would noticeably help.  I work mostly digital but some SSB.  Any helpful opinion would be appreciated.
Consider that the Butternut HF6V stands at 26 feet.  (Yes, I realize it has loading circuits that a straight FPV does not have)

Yes, the extra few feet will help a little.  Whether or not it's significant depends on a lot of factors, including the band in use, the power level, and the number of radials.

I don't think you need the 4:1 unun.  Again, every situation is different, so YMMV.  I'd suggest trying to load it without the unun in place and see what happens. 

I had to redo the concrete base for my FPV last night.  I have 20 feet of aluminum in the air now, with a 2 inch gap at the bottom for the feed (used a fiberglass rod from Max Gain Systems for support and for separation, almost an exact fit for the aluminum tubing I used).  I need now to complete the radial field and get the coax connected. 

I do not plan on using a balun or unun at the base.  I am looking into getting a used mobile "screwdriver" antenna to mount at the base for remote tuning (using the upper section of the FPV in place of the mobile whip).  So there are options.

Should be a fun thing to experiment with this winter!
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Quando Omni Flunkus Moritati.
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N4UM

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RE: "flagpole" vertical height
« Reply #4 on: October 29, 2014, 04:18:41 PM »

w3wn  - I  think you're wise to avoid the unun.  I have used my 23 foot flagpole with and without a 4:1 unun.  After running sweeps right at the feedpoint with my antenna analyzer it turns out that the SWR is much lower without using the unun - except on 30 meters.
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WB6BYU

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RE: "flagpole" vertical height
« Reply #5 on: October 29, 2014, 05:30:07 PM »

Quote from: W3WN

...I am looking into getting a used mobile "screwdriver" antenna to mount at the base for remote tuning (using the upper section of the FPV in place of the mobile whip)...




The screwdriver antenna assembly just adds a variable inductance - that will tune the antenna to resonance
ONLY when the whip is between 0 and 1/4 wavelength, 1/2 and 3/4 wavelength, 1 to 1 1/4 wavelength, etc.
It won't match the antenna when the antenna is slightly longer than an odd multiple of 1/4 wavelength when
the feedpoint impedance is capacitive.

With a 20' radiator you should be able to get a match on 40m and 80m, but not on 20m unless you add a
series capacitor at the feedpoint.


It also won't match the resistive component.  It may be useable when the R value is below 100 ohms or so,
but on some bands if it is 500-j200 ohms then adding +200 ohms of inductance still leaves you with a 10 : 1 SWR.

So I'd recommend some modeling to see what lengths of antenna will work best for the bands that are most
important to you, because there are a number of combinations of lengths and bands that won't tune at all with that approach
« Last Edit: October 29, 2014, 05:32:40 PM by WB6BYU »
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KX4TT

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RE: "flagpole" vertical height
« Reply #6 on: October 30, 2014, 05:39:45 AM »

You've gotten good advice to remove the unun - you can replace it with ferrite beads to avoid feedline radiation and RFI. Also, more radials is better. My additional advice is to get a remote auto-tuner and use it at the feedpoint. I have used the SGC series of tuners for years and they are quite effective.  The SG-237 (or similar) will match your 19 foot antenna easily down to 40, and you might work some 80m. I would go to AD5X's website and read his articles on 43-foot antennas; as your 19 foot (and your proposed 24 foot) antenna are shortened verticals with reference to 40m, the articles are relevant for your situation. The advantage of this is frequency flexibility, and less loss due to the impedance mismatches at the antenna feedpoint.

An additional idea is to use an inductive shunt for 30/40 meters. While lacking the flexibility of an autotuner, it can still provide some inductive reactance which is sorely needed for a 19 foot vertical used on 40m. A few turns of #10 on a 11/2" PVC pipe should work OK for that purpose...........

73 es GL de Lee KX4TT
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WA7PRC

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RE: "flagpole" vertical height
« Reply #7 on: November 03, 2014, 03:10:41 PM »

I live in a HOA area where antennas are not permitted but I currently have a vertical in the backyard that resembles a flagpole enough to avoid any issues so far. [snip]
You're aware that antennas are not permitted yet, you erected one anyway. Of course, you tried or considered options* before knowingly violating the contract you signed?

* Such as mobile/portable/remote/club operations.
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WB2KSP

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RE: "flagpole" vertical height
« Reply #8 on: November 04, 2014, 05:30:44 AM »


[/quote]
You're aware that antennas are not permitted yet, you erected one anyway. Of course, you tried or considered options* before knowingly violating the contract you signed?

* Such as mobile/portable/remote/club operations.
[/quote]

Interesting, and I am not accusing you of anything and this is not a political statement but I find it ironic that while the ex communist nations of the eastern block had club stations for their operators (there were relatively few private stations in Eastern Europe) we in the west had private stations. Today there are many private stations in eastern Europe and in the US it's getting more difficult to find a home that allows the owner the freedom to operate their legal, licensed amateur radio station.
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AA4HA

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RE: "flagpole" vertical height
« Reply #9 on: November 04, 2014, 07:47:03 AM »

I live in a HOA area where antennas are not permitted but I currently have a vertical in the backyard that resembles a flagpole enough to avoid any issues so far. [snip]
You're aware that antennas are not permitted yet, you erected one anyway. Of course, you tried or considered options* before knowingly violating the contract you signed?

And your point is?

The HOA would not create a set of rules to outlaw RF energy. If you follow their press releases it is about the aesthetic of the neighborhood. If you can install an antenna in an enclosure (like a flagpole) that is not prohibited on aesthetic grounds then more power to ya.

If you wanted to run a wire in your attic and push a kilowatt through it they would have no say in the matter either. Would you argue that the attic is just a way of disguising an antenna?
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Ms. Tisha Hayes, AA4HA
Lookout Mountain, Alabama

WB2KSP

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RE: "flagpole" vertical height
« Reply #10 on: November 04, 2014, 08:44:13 AM »

I live in a HOA area where antennas are not permitted but I currently have a vertical in the backyard that resembles a flagpole enough to avoid any issues so far. [snip]
You're aware that antennas are not permitted yet, you erected one anyway. Of course, you tried or considered options* before knowingly violating the contract you signed?

And your point is?

The HOA would not create a set of rules to outlaw RF energy. If you follow their press releases it is about the aesthetic of the neighborhood. If you can install an antenna in an enclosure (like a flagpole) that is not prohibited on aesthetic grounds then more power to ya.

If you wanted to run a wire in your attic and push a kilowatt through it they would have no say in the matter either. Would you argue that the attic is just a way of disguising an antenna?


Running full legal power in an attic is not a smart thing to do. The RF field within the home would be at dangerously high levels. Sure you can put an antenna in the attic thus getting around the rules. Sneaking in an antenna is not for me but that's just me. I've never had to live under those kind of restrictions. Even when I lived in an apartment I was able to put a few antennas on the roof. 
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AA4PB

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RE: "flagpole" vertical height
« Reply #11 on: November 04, 2014, 09:31:32 AM »

Most HOA rules state no OUTSIDE antennas and that doesn't prohibit an attic antenna. If yours does state no antennas period then you'd better get rid of your cell phones and wireless router.
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Bob  AA4PB
Garrisonville, VA

K4FMH

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RE: "flagpole" vertical height
« Reply #12 on: November 08, 2014, 11:46:45 AM »

AA4PB: you've hit the central point of the matter in terms of "banning antennas"! Looking up Vincent K4EZD's location in Google Earth, it appears that his neighbor has a small satellite dish attached to a brick chimney. This is in compliance to the Federal OTARD regs passed years ago! The HOA can state "no antennas" but they cannot ENFORCE a contract provision discovered to violate local, state or federal law. As I've said, with the point having been confirmed by a local real estate lawyer who is also a ham, a provision of a private contract which violates standing law(s) cannot be enforced. Therefore, it's useless! Otherwise, prostitution and illicit drug sales would be protected by their "private contract" standing.

When lawyers boiler-plate these provisions, most just do not know enough about the electronics involved. Hence, the remote garage door opener, cell phones, marine radio on the sailboat in the neighborhood marina (in my own neighborhood's case), and so forth are also verboten by the terms of the HOA CC&Rs. The OTARD regs protect some over the air antennas. However, the evolution of home control technology and other convenience technology (e.g., putting stroke monitors for golfers have transmitters and receivers) make the complete banning of "antennaes, aerials" nearly impossible to enforce.

Now, let's get back to Vincent's question: my solution thus far has been the following. I have an approved birdhouse mounted behind a brick fence. It's PVC painted to match CC&R detail colors with a lightweight wood birdhouse mounted on top. It just might have a Hustler 4BTV inside the PVC. No one can tell since my CC&R's specifically state that "aerials" cannot be visible from the street. Neither are the 24 radials now buried in the grass. Nor can the MFJ tilt-plate so I can lower the birdhouse to refill the seed...or when the wind gets too high. I also have a horizontal wire loop running 1" underneath my shingle's edge. I have an MFJ 80/40M dipole running along the peak of the inverted V shape of the roof. I used 6" plastic standoffs for electric fence bought at Tractor Supply Company. Following Bob Heil's phased wire beam---as also implemented by AC0C before he moved to the country---for 20M. A 2M/70cm dual band Ventenna was installed when I built the house over a vent tube. Even the plumber who installed it can't tell which pipe is the antenna. Therefore, not visible as an antenna. I plan to install a 2M/70cm beam on a lightweight rotor in the walk-in attic as well as a discone Rx/Tx antenna for stuff above 30mHz. I run 500 watts or so to the vertical. I try not to run power to the wire dipoles in the attic but I have thick plastic barriers at the ends of those dipoles to reduce the potential for arc'ing for when I feel I need to.

Vincent, your mileage may vary. But make the best of your situation. Ignore the comments to shame you on your HOA CC&Rs you agreed to follow. As a member of the HOA, you also have the right to change those CC&R's which do not help in maintain property values. Having Nazi-style HOA management theoretically reduces the "value" of the neighborhood, too, as I've had real estate friends say that the reputation of some neighborhood HOA Boards has cost them sales...just like a cell tower would. Enjoy ham radio!
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WA7PRC

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RE: "flagpole" vertical height
« Reply #13 on: November 10, 2014, 06:36:57 PM »

Quote
You're aware that antennas are not permitted yet, you erected one anyway. Of course, you tried or considered options* before knowingly violating the contract you signed?

* Such as mobile/portable/remote/club operations.

Interesting, and I am not accusing you of anything and this is not a political statement but I find it ironic that while the ex communist nations of the eastern block had club stations for their operators (there were relatively few private stations in Eastern Europe) we in the west had private stations. Today there are many private stations in eastern Europe and in the US it's getting more difficult to find a home that allows the owner the freedom to operate their legal, licensed amateur radio station.
This isn't about any government-issued prohibition. This is strictly about the private contract the OP signed so, I don't how your mention of governments in Eastern Europe has ANY bearing on this (unless you're inferring that I'm a communist). I've been called that before by someone wanting his way (against rules/law), and it was just as ironic then.

The OP said his HOA prohibits antennas, yet he has one. He is knowingly not in compliance w/ the contract he signed. However, that aside, if he wants to comply while "going stealth", he should make sure the "flagpole" complies with that part of his contract.  While the HOA can't prohibit a flag pole, it MAY limit the height and placement of the "flagpole", and when it can be erected/flown. I recommend checking the HOA rules about that.
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WA7PRC

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RE: "flagpole" vertical height
« Reply #14 on: November 10, 2014, 06:45:30 PM »

Ignore the comments to shame you on your HOA CC&Rs you agreed to follow.
Are you going to pay any fines levied by the HOA and/or the OP's attorney fees? When I went through the process to install a tower, MANY hams suggested I ignore the zoning and permitting requirements, and just put it up. After all, this is 'merica and 'mericans should not be limited by laws or contracts.  When I asked those people if they would pay any fines etc, the silence was deafening.

IMO, ignoring the contract should not be the FIRST and ONLY way of dealing with it.  I suggest the OP start by going over his contract with a fine-tooth comb. After that, consider the possibilities.
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