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Wideband antenna

 

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.

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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?

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Thank you!

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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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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.
 

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

On Wed, Apr 9, 2025 at 7:37?PM Mihai via <mihai=[email protected]> wrote:
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?
?



--
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.
 

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 9:01?PM Stan Dye via <standye=[email protected]> wrote:
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.



--
Dave - W?LEV
 

开云体育

? 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
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----- Original Message -----
From: W0LEV via groups.io <davearea51a@...>
Reply-To: <[email protected]>
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 9:01?PM Stan Dye via <standye=[email protected]> wrote:
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.



--
Dave - W?LEV
 

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?

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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?
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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:
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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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Thank you!
 

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
 

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

Virus-free.


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



--
Dave - W?LEV
 

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


On Thu, Apr 10, 2025 at 9:50?AM W0LEV via <davearea51a=[email protected]> wrote:
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

Virus-free.

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



--
Dave - W?LEV
 

Thank you all for recommending affordable log periodic antennas!
The PCTEL OP451 (450 MHz – 6 GHz, vertical polarization) I found is around $90 (used, not new).
Is it worth that price tag?
?
As I mentioned before, my use-case is (trying) to measure the field strength, but also see the spectrum (therefore SA).
The math to go to V/m or W/m2 goes through antenna aperture, distance, frequency, etc.
But I don't know if I need to know mine as a receiver or the emitter's antenna aperture?
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I thought (as a newbie) that if I can measure the amount of power (measured with TinySA) arriving at my probe/antenna and knowing the antenna surface I can do some math from there...
But I also think that not all antenna surface is involved in "coupling" with certain frequencies and I don't know if this is the right way to go...
Should I open a new topic on the differences between measuring E-field (e.g. Narda) and scanning the signals power levels (dBm or Watts) with TinySA + math?
Thank you all for guiding me in this
 

So, I asked ChatGPT and gave me this answer:
Is "shortcut formula" good enough for my use-case?
 

If you are interested in knowing the field strength at your location, you only need to consider the equipment at your end. It makes no difference how the field happened to get there. If you are designing a communication system link budget then you would need to consider both ends.?

I have one of the WA5VJB antennas and he does a nice job, if it matches your frequency range of interest.
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Good luck!
Craig
 

I will first try with PCTEL OP451 omni wb antenna and will also take into consideration at least a log antenna.
Already calculated all required info, specially AF (needed as input into TinySA - TRACE/CALC/TABLE TRACE)
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