Ultimate portable 800MHz antenna shoot-out!

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Anderegg

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Alrighty.........I want to do an ultimate 800MHz scanner antenna shoot-out. I have a Uniden 396XT and 436HP for testing, and the following antennas with or without adapters for trials.

1: Radio Shack 800MHz 5/8 wave whip
2: SpectrumForce 2db 7-800MHz 5/8 wave whip
3: ScannerMaster 800MHz dipole
4: ScannerMaster 800MHz 1/4 wave spike
5: Motorola 800MHz 5/8 wave whip
6: Motorola 800MHz 1/4 wave spike
7: Motorola 800MHz dipole

The RS800 has a BNC, the Motorolas have SMA-F, and the rest are standard Uniden SMA-M. Appropriate adaptors are attached to each scanner. I don't know of any other portable 800MHz antennas (popular) to test, so this is what I have available.

Now, for the testing. How best to do this? I was thinking a distant 800MHz control channel, and use FreeScan's logging signal strength numbers averaged, or the virtual control screens green signal meter. Would like to be able to produce some usable figures, and not measure a wavering fluctuating simulcast frequency, to keep the measurements as relative as possible.

BTW, the SpectrumForce 7-800MHz whips are currently under $8 at ScannerMaster currently.

Paul
 

Firefox89

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I have the RS800... would you say that one is the best? I'm looking for an overall good antenna for uhf and 800... what one would you say faired the best?
 

Anderegg

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The RS800 is the defacto standard by which others will be judged. it requires a large and heavy metal SMA adaptor for Unidens, which makes it cumbersome and awkward to hold a 396XT with it attached. Once I figure out the best way to get an RSSI or signal strength reading off my radios, the tests will begin.

Paul
 

mm

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a SDR dongle running any of the Spectrum analyzer apps would be better than an scanners RSSI meter.

using an off air long distant signal will not work well as you will plagued with frustrating multipath reflections that throw your measurements off.

For each antenna tested make a good metal/aluminum ground plane that is the correct size for each antenna and confirm that each has a adequate impedance match prior to connecting to the sdr dongle.

Set up outside in a large field away from any objects that could cause reflections and place antennas several wavelengths apart.

Use a quarter wave matched and widebsndwidth antenna that is your transmit antenna which should be fed from a RF generator with a signal level that is centered on the sdr dongles spectrum analyzers screen.

I did this exact method testing out various internal antennas which were to be used in a 978 to 1090 MHz aviation portable ADS-B receiver with good results.

I was looking for impedance match, bandwidth (978 to 1090 MHz) and efficiency/gain over a reference fat quarter wave transmit antenna that covered the entire measurement bandwidth.

Aside from the RF generator source everything else including the sdr dongle was easily acquired and easy to set up.

Good luck, antenna measurement can be fun but also frustrating.
 

Anderegg

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MM, should I introduce my own low powered semi distant transmitter source, or would actual transmitter tower source be a better source? I need to find a location where the signal meter on the scanner doesn't rise and fall all the time on 800MHz.....very annoying issue.

I have an Icom IC-PCR100, does that have any use for this testing? It works, and I have the software for it still.

Paul

SDR - Software Defined Radio
 

Anderegg

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OK, I pulled an old Icom IC-PCR100 out of storage, and after dusting it off and buying a USB to serial port converter, have got it running TalkPCR software. It has the option for dbm signal stregth with an old analog style meter needle swinging right and left.

I am now in the process of ordering any specific adaptors necessary to attach everything to the BNC jack. I have hard mounted the Icom vertically, with the BNC connector pointing straight up, so the whole rig cannot be moved. For additional testing, I purchased a mirror mount NMO mount, which has a BNC cable and is hard mounted to a cabinet handle. Also purchasing the required NMO to SO-239/PL259 etc etc etc adaptors. Will run a few mobile antennas such as the Larsen NMO800 and a huge 3 foot tall trilinear 5db gain 800 antenna made by PCTEL against the handheld antennas on the same mount. The adavantage of this NMO system is I can attach it to the roof of my car for additional testing.

Paul
 
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OK, I pulled an old Icom IC-PCR100 out of storage, and after dusting it off and buying a USB to serial port converter, have got it running TalkPCR software. It has the option for dbm signal stregth with an old analog style meter needle swinging right and left.

I am now in the process of ordering any specific adaptors necessary to attach everything to the BNC jack. I have hard mounted the Icom vertically, with the BNC connector pointing straight up, so the whole rig cannot be moved. For additional testing, I purchased a mirror mount NMO mount, which has a BNC cable and is hard mounted to a cabinet handle. Also purchasing the required NMO to SO-239/PL259 etc etc etc adaptors. Will run a few mobile antennas such as the Larsen NMO800 and a huge 3 foot tall trilinear 5db gain 800 antenna made by PCTEL against the handheld antennas on the same mount. The adavantage of this NMO system is I can attach it to the roof of my car for additional testing.

Paul
I have a PCTEL 800MHz 3db gain mobile antenna that performs great. You will always see the difference in the mobile antenna vs the portable antenna. I have tested rubber duck 800MHz antennas by Laird to the PCTEL 800MHz antenna. The mobile did the best.
 

prcguy

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This would not be the right way to test antennas intended for portable scanner use. You would not want a ground plane and instead an old hand held scanner or similar size plastic box with a similar amount and shape of metal as the scanner chassis and circuit board.

You then attach a test cable from the handheld test chassis antenna connector to feed a spectrum analyzer or input to a scalar or vector network analyzer and decouple the cable from the test chassis with a common mode ferrite choke so it has no influence on the scanner antenna under test.

The reason you do all this is because a handheld scanner does not have a tuned or adequate ground plane during normal operation so you want to create the same environment for testing. If you test a particular antenna with a perfect ground plane it may test better than another, but without the ground plane as on the scanner it may be worse and now everyone goes out and buys a recommended antenna that is not really the best when used on a scanner.
prcguy


a SDR dongle running any of the Spectrum analyzer apps would be better than an scanners RSSI meter.

using an off air long distant signal will not work well as you will plagued with frustrating multipath reflections that throw your measurements off.

For each antenna tested make a good metal/aluminum ground plane that is the correct size for each antenna and confirm that each has a adequate impedance match prior to connecting to the sdr dongle.

Set up outside in a large field away from any objects that could cause reflections and place antennas several wavelengths apart.

Use a quarter wave matched and widebsndwidth antenna that is your transmit antenna which should be fed from a RF generator with a signal level that is centered on the sdr dongles spectrum analyzers screen.

I did this exact method testing out various internal antennas which were to be used in a 978 to 1090 MHz aviation portable ADS-B receiver with good results.

I was looking for impedance match, bandwidth (978 to 1090 MHz) and efficiency/gain over a reference fat quarter wave transmit antenna that covered the entire measurement bandwidth.

Aside from the RF generator source everything else including the sdr dongle was easily acquired and easy to set up.

Good luck, antenna measurement can be fun but also frustrating.
 
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