WB4APR's summary matches my personal assessment of eggbeaters, having tried them on LEO's myself for a period of test: Eggbeaters are mediocre at best for our LEO, amateur satellite fleet.

There are situations eggbeaters may have their place:

1. A fixed installation, such as telemetry gathering, in which you absolutely can't afford risk of mechanical rotor failure.

2. A backup to a directional array.

3. The satellite has a very strong downlink.

Beyond that I can't recommend them for anyone. I learned, like Bob said below, that a 1/4 wave ground plane on 2m is as effective or better. I've copied thousands of telemetry frames with an inexpensive, SO-239 chassis connector-based ground plane. This was in a very low-noise area with no obstructions. Keep the feedline as short as possible, use quality feedline, and consider use of RX preamplifier as necessary.

I will say this, people DO make contacts on eggbeaters. They also make contacts with mobile whips and rubber ducks. Some folks are more successful than others at this. On a regular basis I can quickly ascertain when the other station in QSO with me is on an eggbeater or omni.

Two major factors at play can make or break an eggbeater being useful:

1. Terrain/obstructions. Eggbeaters in the middle of your forested backyard are a total waste. Can you put them on the roof if it clears the trees? Are you in the concrete jungle?

2. RFI/noise. Eggbeaters are far more prone to local RFI than a directional antenna aimed at the satellite. I've seen some situations where an omni couldn't copy a single telemetry frame, yet a 2 element yagi was copying the telemetry in exactly the same observation point from horizon to horizon.

In summary, I would recommend building an eggbeater with scrap materials versus buying a commercial one, so that no tears are shed over lost money once it's tossed into the rubbish bin.

73, Clayton W5PFG

On 5/3/2019 16:32, Robert Bruninga via AMSAT-BB wrote:

Eggbeaters are ideal antennas for omnidirectional coverage with dual polarization for strong signals with minimum fades....

But like any antenna, to get gain somewhere, you have to give up gain elsewhere. Here are all the issues and my opinions.

1. Satellites on the horizon are 10 dB farther away than ones above 22

degrees (2000 miles vs 700 miles). 2) Splitting gain into circular polarization (Eggbeaters) loses 3 dB compared to incoming linear polarization 3) Small sats usually have linear antennas or, if they have cross polarization then even if they are RHCP when approaching, they may be LHCP going away, thus you still have a 50/50 chance of having a polarization mismatch, though having both polarizations will minimize most fades. 4) Most small Amateur sateliltes have less than 1W transmitters and simply cannot be heard on the horizon without several dB gain.

My Conslusions are:

1. An Egg beater is ideal for STRONG satellites (Think ISS with 10 Watts).

It will minimize fades horizon to horizon. 2) But there are NO, NONE, NADA current amateur satellites (not even the ISS right now) at that power level. 4) Hence an eggbeater even with a dB or so gain on the horizon simply is not going to hear anything until the satellite gets above about 20 degrees (when it is 10 dB closer) 5) So, why even bother with an eggbeater. 6) Use a simple 19.5" quarter wave vertical over a ground plane (for 2m). It will have 5 dBi gain above about 15 degrees (several dB better than an eggbeater). 7) and it will ALSO WORK even better as a 7 dBi gain UHF antenna (3/4 wave vertical) above about 25 degrees up to 70 degrees (6 dB better than an Eggbeater)...

AND it is DUAL band as well! (on the same coax!)

BUT, what about the donut hole overhead for these vertical antennas?

Forgetaboutit.!.... The satellite is only above 70 degrees about 1% of the total pass times per day! And then for less than about 30 seconds!

To visualize the orbit actual geometry see the scale plot on: http://aprs.org/LEO-tracking.html

So, in my humble opinion, a 19.5" vertical whip antenna in the middle of a car roof (neat ground plane) will give pretty good satellite coverage. It will have some fades due to only one polarization, but the strong part of the cycle will be 3 dB stronger than it would be on a dual polarizatiaon antenna. And you don't have to be parked on a mountain. Since again, no omni antenna can hear these weak satellites on the horizon anyway, so as long as the trees are far enough away to give you sky above about 20 degrees, you will have about the best coverage you can get for about a 20" of copper wire and a nice ground plane..

In my opinion anyway.

AND*** If you want to hear them all the way horizon to horizon, buy a $65 TV rotator and attach a small 5 to 6 element beam tilted up at about 15 degrees and hear them all! See above web page...

Bob, Wb4APR

Hello Space Communicators!

Here are some observations about Satellite APRS on 145.825 MHz.

1) Receiving is harder than Transmitting. 2) Location is critical, avoid hill tops or parking structures in a city.

As far as Satellite APRS on 145.825 MHz with an Eggbeater, here are some reference points.

My Dad (N6DAN) operates the #1 iGate in the world based on packets received on 145.825 MHz. So, I think that documented track record carries a great deal of merit and credibility. Having said that, he operates two radios, one connected to the EBB144 and another to a directional antenna.

Egg Beater success pivots on two factors:

1) Pre-amp: the EBB is dull and needs help. 2) Noise: the EBB is useless in the city on a high pole, but perfect in rural areas on a high pole. In the city the EBB works best below a wood fence line.

W0ARP operates the #8 iGate in the world based on packets received on 145.825 MHz. He is only running the EBB144 with a pre-amp in a rural area.

Eggbeaters can be useful.

73s

Robert MacHale KE6BLR Ham Radio License http://spaceCommunicator.club http://spacecommunicator.club/ Supporting Boy Scout Merit Badges in Radio and Space Exploration

On Fri, May 3, 2019 at 2:49 PM Robert Bruninga via AMSAT-BB < [email protected]> wrote:

Eggbeaters are ideal antennas for omnidirectional coverage with dual polarization for strong signals with minimum fades....

But like any antenna, to get gain somewhere, you have to give up gain elsewhere. Here are all the issues and my opinions.

1. Satellites on the horizon are 10 dB farther away than ones above 22

degrees (2000 miles vs 700 miles). 2) Splitting gain into circular polarization (Eggbeaters) loses 3 dB compared to incoming linear polarization 3) Small sats usually have linear antennas or, if they have cross polarization then even if they are RHCP when approaching, they may be LHCP going away, thus you still have a 50/50 chance of having a polarization mismatch, though having both polarizations will minimize most fades. 4) Most small Amateur sateliltes have less than 1W transmitters and simply cannot be heard on the horizon without several dB gain.

My Conslusions are:

1. An Egg beater is ideal for STRONG satellites (Think ISS with 10 Watts).

It will minimize fades horizon to horizon. 2) But there are NO, NONE, NADA current amateur satellites (not even the ISS right now) at that power level. 4) Hence an eggbeater even with a dB or so gain on the horizon simply is not going to hear anything until the satellite gets above about 20 degrees (when it is 10 dB closer) 5) So, why even bother with an eggbeater. 6) Use a simple 19.5" quarter wave vertical over a ground plane (for 2m). It will have 5 dBi gain above about 15 degrees (several dB better than an eggbeater). 7) and it will ALSO WORK even better as a 7 dBi gain UHF antenna (3/4 wave vertical) above about 25 degrees up to 70 degrees (6 dB better than an Eggbeater)...

AND it is DUAL band as well! (on the same coax!)

BUT, what about the donut hole overhead for these vertical antennas?

Forgetaboutit.!.... The satellite is only above 70 degrees about 1% of the total pass times per day! And then for less than about 30 seconds!

To visualize the orbit actual geometry see the scale plot on: http://aprs.org/LEO-tracking.html

So, in my humble opinion, a 19.5" vertical whip antenna in the middle of a car roof (neat ground plane) will give pretty good satellite coverage. It will have some fades due to only one polarization, but the strong part of the cycle will be 3 dB stronger than it would be on a dual polarizatiaon antenna. And you don't have to be parked on a mountain. Since again, no omni antenna can hear these weak satellites on the horizon anyway, so as long as the trees are far enough away to give you sky above about 20 degrees, you will have about the best coverage you can get for about a 20" of copper wire and a nice ground plane..

In my opinion anyway.

AND*** If you want to hear them all the way horizon to horizon, buy a $65 TV rotator and attach a small 5 to 6 element beam tilted up at about 15 degrees and hear them all! See above web page...

Bob, Wb4APR

-----Original Message----- From: AMSAT-BB [email protected] On Behalf Of Devin L. Ganger via AMSAT-BB Sent: Friday, May 3, 2019 4:19 PM To: [email protected] Subject: [amsat-bb] ARRL Antenna book, eggbeater antenna designs

Greetings, programs!

I'm looking to work with my son (who will be studying to get his Technician license later this month) on building a UHF/VHF pair of eggbeater antennas. I've found a few papers online, but does anyone have a good reference to a detailed design?

Does the ARRL Antenna book latest edition have any significant coverage of eggbeaters at all? I have an older version that has nothing.

Also, most of the designs I see are for a single band. If you're deploying a pair for satellite operations, do you simply attach them through a duplexer? I have a Diamond MX-72N that I picked up a while ago for using with dual Baofengs, but it's been sitting in my drawer since I picked up my TH-D72A. It has a 1.6~150MHz lead and a 350~460MHz lead.

Thanks in advance for any pointers you might have.

-- Devin L. Ganger (WA7DLG) email: [email protected]mailto:[email protected] web: Devin on Earthhttp://www.devinonearth.com/ cell: +1 425.239.2575

---

Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: https://www.amsat.org/mailman/listinfo/amsat-bb _______________________________________________ Sent via [email protected]. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: https://www.amsat.org/mailman/listinfo/amsat-bb