WA5VJB makes several log periodics:
Note, Kent spent a LOT of time developing these antennas. They are made for a specific dielectric constant for FR4/G10. The dielectric constant for FR4 and G10 on the market varies widely and wildly. Kent ordered a large quantity of the pc board material so it would have the same dielectric constant and probably last him a lifetime. Others have copied his designs but made them on pc material with a different dielectric constant. They will NOT perform as his designs do. A lot of these imitation boards are available on Amazon and eBay. I would buy the ones directly from Kent.
Zack W9SZ
There are also available printed LPs with included antenna factors already documented.? And.... considerably less $$ than the referenced Amazon units.? Just do a www search.
Dave - W?LEV
On Thu, Apr 10, 2025 at 12:22?PM Donald S Brant Jr via <dsbrantjr= [email protected]> wrote: I use this PC board-based log-periodic antenna for EMI searching: ?
To be reasonably useful I put a preamp right on the antenna connector. ?
The internal battery makes it very convenient.
Best regards, Don Brant
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There are also available printed LPs with included antenna factors already documented.? And.... considerably less $$ than the referenced Amazon units.? Just do a www search.
Dave - W?LEV
On Thu, Apr 10, 2025 at 12:22?PM Donald S Brant Jr via <dsbrantjr= [email protected]> wrote: I use this PC board-based log-periodic antenna for EMI searching: ?
To be reasonably useful I put a preamp right on the antenna connector. ?
The internal battery makes it very convenient.
Best regards, Don Brant
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I use this PC board-based log-periodic antenna for EMI searching: ?
To be reasonably useful I put a preamp right on the antenna connector. ?
The internal battery makes it very convenient.
Best regards, Don Brant
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My goal is to have a "good-enough" and cost-effective antenna for the 600 MHz - 6 GHz spectrum
As a probe for scanning how the spectrum is occupied and at what power levels are the signals.
I think I need an Isotropic/omnidirectional probe, as I am not really interested in "finding" the source.
I don't know how much the Schwartzbeck log periodic antenna cost, in what price range it sits?
?
Regarding TinySA Ultra, with any of the mentioned antenna, I must use TRACE > CALC > TABLE TRACE (and save it to SD)?
And create a trace containing a 8 point linear interpolation of the AF versus frequency from the antenna gain graph
I can calculate/estimate AF from the gain graph here: https://www.everythingrf.com/rf-calculators/antenna-factor-calculator
Is it ok(ish) to "approximate" the 20 points graph to only 8 points in the TABLE TRACE?
?
Also, looking at the Narda SRM-3006 probe (E Field Probe 27MHz - 3GHz), it could also have vertical polarization like my above-mentioned PCTEL OP451?
?
Is there something I must know about the (big?) differences between measuring E-field (Narda) and scanning the signals power levels (dBm or Watts)?
At the moment I have this as a starting point:
?
source: 2
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And, as I only receive/measure "in the air" and don't know the emitting antenna's aperture, how can I go from there?
?
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Re: Determining antenna factor
Hi Charlie,
Can I assume G is dBi not dBd
I presume G is gain.? Is that in dB or the numerical ratio before the 10log[ratio]?
Dave - W?LEV
A handy formula…..plot your antenna gain vs. frequency and convert to AF vs. frequency
?
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-Charlie
?W5CDT
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? Hello Dave
?
? I'd be interested to know more about your disc dipole experiment, size and materials etc?
? A Google search brought up nothing.
?
? 73s Tracey G5VU
?
toggle quoted message
Show quoted text
----- Original Message -----
Sent: 09/04/2025 22:28:49
Subject: Re: [tinysa] Wideband antenna
A better option to the discone is the bicone.? Sure, it's larger, but behaves a bit more like the LP over frequency, but without the directionality.? For his purpose, the discone may serve as the best choice.? I can't imagine what the Schwartzbeck costs.? It's a professional antenna widely used in EMC measurements for radiated emissions.?
If he really wants bandwidth, build a disc dipole.? I recently built an ugly version.? It measured well at or (mostly) under 2:1 from 135 MHz through 3 GHz and the pattern is dipolish.? Off hand I am not aware of anyone marketing such an antenna.? Someone should!
Dave - W?LEV
Dave - W?LEV
On Wed, Apr 9, 2025 at 01:09 PM, W0LEV wrote:
The Schwartzbeck log periodic is by far the better antenna.? I agree 100%, Dave.
At least if directionality is the goal.
Since the OP originally posted a vertical antenna, I presumed he wanted omni-directionality with flat gain over a large bandwidth.
And if that is the case, the discone is a better choice than his vertical or the log periodic antenna.
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A better option to the discone is the bicone.? Sure, it's larger, but behaves a bit more like the LP over frequency, but without the directionality.? For his purpose, the discone may serve as the best choice.? I can't imagine what the Schwartzbeck costs.? It's a professional antenna widely used in EMC measurements for radiated emissions.?
If he really wants bandwidth, build a disc dipole.? I recently built an ugly version.? It measured well at or (mostly) under 2:1 from 135 MHz through 3 GHz and the pattern is dipolish.? Off hand I am not aware of anyone marketing such an antenna.? Someone should!
Dave - W?LEV
Dave - W?LEV
On Wed, Apr 9, 2025 at 01:09 PM, W0LEV wrote:
The Schwartzbeck log periodic is by far the better antenna.?
I agree 100%, Dave.
At least if directionality is the goal.
Since the OP originally posted a vertical antenna, I presumed he wanted omni-directionality with flat gain over a large bandwidth.
And if that is the case, the discone is a better choice than his vertical or the log periodic antenna.
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On Wed, Apr 9, 2025 at 01:09 PM, W0LEV wrote:
The Schwartzbeck log periodic is by far the better antenna.?
I agree 100%, Dave.
At least if directionality is the goal.
Since the OP originally posted a vertical antenna, I presumed he wanted omni-directionality with flat gain over a large bandwidth.
And if that is the case, the discone is a better choice than his vertical or the log periodic antenna.
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Re: Determining antenna factor
I presume G is gain.? Is that in dB or the numerical ratio before the 10log[ratio]?
Dave - W?LEV
A handy formula…..plot your antenna gain vs. frequency and convert to AF vs. frequency
?
?
-Charlie
?W5CDT
?
?
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The Schwartzbeck log periodic is by far the better antenna.? They offer a far flatter response response and are directional.? Directionality allows one to do a better job of finding RF emission locations.?
The gain plot for the "vertical" blob is over rated!!?
Discones can typically cover a 10-to-1 bandwidth while staying on or within the 2 : 1 circle on the Smith chart but are not directional and do not offer constand polarization with frequency.? Their only claim to fame is a 2 : 1 SWR over a 10-to-1 bandwidth.? They operate about like a 1/4-wavelength for the frequency of coverage.
Again the Schwartzbeck is by far the best choice.? I've used them professionally as do many accredited labs.??
Dave - W?LEV
I am asking first about the PCTEL OP451 antenna, but also in comparison with, say, a Schwarzbeck USLP 9143 Log Antenna ()
As I need the antenna as a mobile probe, which one/type is better to cover monitoring 900 MHz - 6/7 GHz spectrum with TinySA?
?
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In general, a log-periodic antenna will give flatter gain response over a wide frequency range than will a vertical antenna.
But the log-periodic antenna is more directional (in the direction of the 'arrow' of smaller radiators), so its forward gain will be different from signals off the side or back.
You should also consider a discone design, which is more omni-directional, but more even gain across the bandwidth.
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I am asking first about the PCTEL OP451 antenna, but also in comparison with, say, a Schwarzbeck USLP 9143 Log Antenna ()
As I need the antenna as a mobile probe, which one/type is better to cover monitoring 900 MHz - 6/7 GHz spectrum with TinySA?
?
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Re: Determining antenna factor
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Anybody used PCTEL OP451 (450 MHz – 6 GHz, VSWR <2.0:1, 50 Ohm) wideband antenna with TinySA Ultra?
It is a good match? Anybody had any experience with this one or a similar antenna? Pros and cons?
Should I be worried about cable length?
Specs seems to indicate that gain values include cable and connector losses.
?
And reading the messages in group, I MUST use TRACE/CALC/TABLE TRACE and create a trace containing a 8 point linear interpolation of the AF versus frequency from the antenna gain graph?
Is it ok to "approximate" the graph points to only 8 points in the TABLE TRACE?
?
Thank you!
?
 ?
?
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Re: tinySA Ultra - signal generator specs
Well that wasn’t very smart! ?Yes, I’ve found the correct page now - thanks.?
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Re: tinySA Ultra - signal generator specs
You are reading the tinySA basic spec, try the tinySA Ultra spec
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Designer of the tinySA
For more info go to
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tinySA Ultra - signal generator specs
I'm trying to use the signal generator again, as I have many times.? But I'm looking for a bit more power than before.? I see that it is specified (at ) as -6 dBm in the "low" mode and +9 dBm in the "high" mode.? Yet the most I can get out of it is -17.9 dBm.? I must be missing something - what did I do?? This is the ZS405 version, I think.
Ron
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Did you read the change log?
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Designer of the tinySA
For more info go to
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I'll ask the question in a different way. There are versions in the tiny SA Ultra line (ZS-405, ZS-406, ZS-407) that probably differ in hardware. The latest versions of the software are mainly focused on the ZS-406,ZS-407 and are designed for this hardware (I may be mistaken). And now, if you use the latest software versions in the ZS-405, will this update have an improvement in performance? That's the question I'm interested in.I would like to hear the answer to my question from the creator of these devices.
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That's only with the FW release after the introduction of the Ultra+
If you run older FW there is no indication. Just tinySA Ultra, which means ZS405
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Designer of the tinySA
For more info go to
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Donald S Brant Jr
R4ABT