The Amp Hour Electronics Podcast

Welcome, Pete Bevelacqua of Antenna-Theory.com!

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• Chris first met Pete when he was giving a talk at HDDG about a custom made VNA
  • 0h 0m 55s
• Pete has been an antenna designer at Boeing, Apple, Nest
  • 0h 1m 16s
• Pete got started in this because he really liked Electricity and Magnetism classes.
  • 0h 2m 12s
• “Do I come out [of the class] and know how to put an antenna in a phone?” (answer: no)
  • 0h 3m 4s
• Pete studied with Dr Bilanas at ASU
  • 0h 3m 20s
• Convex optimization program
  • 0h 4m 12s
• Used a lot in signal processing
  • 0h 5m 38s
• Compared to linear optimizations
  • 0h 6m 29s
• Boeing wanted to put 20 antennas on a plane
  • 0h 7m 37s
• DC to daylight
  • 0h 8m 20s
• Starting with a specific problem
  • 0h 9m 43s
• “I want to put a bluetooth antenna in my device”
  • 0h 9m 51s
• Start from a place of practicality
  • 0h 11m 16s
• Do not make anything hard that doesn’t need to be hard
  • 0h 11m 32s
• The one piece of math you need to know: the lowest frequency you’re using
  • 0h 12m 52s
• Half wavelength for GPS is 3.5 inches
  • 0h 13m 13s
• Efficiency is how much you’re putting in vs what you get out
  • 0h 13m 30s
• Everything in RF is dB
  • 0h 14m 49s
• …except for the antenna
  • 0h 15m 13s
• “This meeting is 3dB too long”
  • 0h 16m 35s
• Didn’t design antennas at Boeing because they didn’t need them to be custom/integrated
  • 0h 18m 53s
• Directionality of antennae
  • 0h 21m 6s
• “Do you want a high gain antenna?”
  • 0h 21m 12s
• Gain specifically is the efficiency (in dB) plus the directivity (in dB)
  • 0h 21m 52s
• FCC matters for consumer. If you have a directional antenna and it’s out of spec, you’ll need to take the overall power down
  • 0h 23m 7s
• Effective Isotropic Radiated Power (EIRP) = conducted power + antenna gain
  • 0h 24m 0s
• dDm is milliwatts of power
  • 0h 24m 59s
• RF and antenna teams are different at hardware companies.
  • 0h 26m 6s
• RF team assumes a 50 ohm antenna. The antenna team assumes a 50 ohm driver.
  • 0h 27m 7s
• Went from Boeing to Apple
  • 0h 28m 7s
• Consumer electronics and how it works
  • 0h 29m 3s
• Industrial design team starts the process for look, feel and materials.
  • 0h 29m 10s
• Mockup or simulation
  • 0h 31m 36s
• Integration and understanding what will be interfering
  • 0h 31m 58s
• Simulation is HFSS and CST
  • 0h 33m 4s
• Pete isn’t big on simulating
  • 0h 33m 16s
• Some people don’t simulate at all
  • 0h 33m 57s
• Not that many types of antennas
  • 0h 35m 3s
• Hybrids of dipoles
  • 0h 36m 7s
• VNA
  • 0h 36m 21s
• VSWR
  • 0h 36m 37s
• VNA just tells you it is matched, not that it’s radiating
  • 0h 37m 1s
• Once it’s matched you go about measuring its efficiency by putting it in an anechoic chamber
  • 0h 37m 42s
• Dealing with multiple frequencies
  • 0h 38m 30s
• GPS, Bluetooth, Wifi, Cellular
  • 0h 38m 45s
• Cellular bands
  • 0h 39m 5s
• Antennas are not meant to reject anything, that’s the job of the filters
  • 0h 40m 20s
• 1850 (MHz) spectrum in cellular
  • 0h 40m 35s
• “The ground in your PCB is part of your antenna”
  • 0h 44m 20s
• How a flat antenna can create a unidirectional radiation
  • 0h 46m 27s
• Omnidirectional is actually a donut pattern
  • 0h 46m 46s
• For lower cellular frequencies, the phone is shorter than half the antenna
  • 0h 47m 33s
• Explaining the polarization without looking
  • 0h 48m 49s
• “The more volume you have the more bandwidth you have”
  • 0h 50m 34s
• Fixing things with an exacto knife
  • 0h 52m 34s
• Choking the lines allows you to select the frequencies
  • 0h 54m 5s
• You start testing cert right away
  • 0h 55m 23s
• Building your own VNA (talk at HDDG)
  • 0h 56m 41s
• Went to Maker Faire, saw someone building a VNA
  • 0h 57m 58s
• Need a bidirectional coupler
  • 1h 0m 9s
• Need a frequency synthsizer
  • 1h 1m 8s
• Coupler has directivity
  • 1h 2m 24s
• Reflected comes back and you can measure with a chip
  • 1h 3m 11s
• Got the Chazwazza (VNA project) on kickstarter, but the demand wasn’t there
  • 1h 4m 0s
• The unit operates from 400 MHz to 2.7 GHz
  • 1h 5m 4s
• Super light, especially compared to commercial equipment
  • 1h 5m 16s
• After VNAs, testing chambers are also useful
  • 1h 6m 36s
• Size of the chamber is a function of the wavelength
  • 1h 6m 54s
• Pete’s current project is putting a working on putting a rocket in a balloon
  • 1h 7m 56s
• Check out more of Pete’s work at Antenna-theory.com
  • 1h 9m 53s