Full Function CW Microwave Frequency Counters with Selective Power Measurement

The 545B and 548B frequency counters are popular in R&D labs and production test settings because they perform multiple duties and a variety of applications. They provide the capability to selectively measure individual signals in a multi-signal environment. Additionally, they can simultaneously measure the average power level of the isolated input signal. The 545B measures CW, FM, and AM frequencies from 10 Hz to 20 GHz, and the 548B extends the range to 26.5 GHz. Optionally, the 548B’s range can be further extended to 110 GHz.

All Phase Matrix EIP® brand frequency counters are based on a unique heterodyne architecture that incorporates a YIG-based preselector. The YIG-preselected input provides unparalleled performance, in amplitude discrimination, frequency selectivity, kickback noise, and burnout protection.


  • Frequency Limits for Selective Frequency and Power Measurements, limits are controlled by keyboard
  • -30 dBm sensitivity
  • Power Measurements to ±0.1 dB resolution, ±0.5 dB accuracy (typ.)
  • Optional Frequency Extension to 110 GHz (548 Only)
  • 10 dB automatic amplitude discrimination
  • 200 msec acquisition time
  • Up to 800 MHz/sec tracking speed
  • 20 MHz P-P FM tolerance up to a 10 MHz rate
  • 200W (+53 dBm) peak damage protection

Unsurpassed Burnout Protection

Typically found in high performance spectrum analyzers; only Phase Matrix counters feature a YIG-preselected microwave input, which provides unparralled burnout protection, FM tolerance and frequency selectivity. The YIG preselector works like a tunable bandpass filter, preventing harmonics and other out-of-band spurious signals from interfering with measurement of the desired signal. It also protects the counter from accidental application of high level signals (up to 200 watts peak), reducing downtime and the associated high cost of repairing damaged microwave circuitry.

Selective Frequency and Power Measurements

With a single connection, the 545B and 548B can simultaneously measure and display the input signals frequency and power level in the microwave band, eliminating the need for a seperate microwave power meter. Within the 25MHz bandwidth of the YIG-preselector, only the selected signals frequency and power level are measured. Signals to be analyzed are selected by keystroke entry of an individual center frequency, or search a range between a low and high frquency limit. This signal selectivity, combined with 20MHz of FM tolerance at all rates up to 10MHz, allows the 545B and the 548B to make accurate frequency and power level measurements even while the input signal is carrying traffic; there is no need to take the transmitter, or adjacent channels, off the air for routine checks.

Frequency Extension to 110 GHz

Option 06 provides the ability to extend the frequency range of your 548B, in bands, up to 110 GHz. Remote sensors allow you to reach out to connect to virtually any wave guide system without the complications of the additional plumbing necessary to bring the signal to your counter. A wide selection of sensors provides measurement capability in the wave guide band that you are working in now, and the flexibility to change as your application changes without having to purchase another counter.

Frequency Limits

Automatic amplitude discrimination enables the 545B/548B counters to automatically select and measure the input signal with the highest level, and ignore all other harmonics and other spurious signals that are present. “Frequency Limits” extend this signal selection capability by allowing you to select upper and lower limits, The counter will measure the frequency and power level of only the highest level signal within these limits – even if there are higher level signals present at the counters input. This gives you the ability to measure the frequency and power of a low level signal (such as a harmonic) even when a signal of much higher level (the fundamental) is present.

Power Measurement

The 545B/548B family of microwave counters offers the optional ability to simultaneously measure both the frequency and power level through the same input. This often eliminates the need for a separate microwave power meter. With the 25 MHz bandwidth of the YIG tuned preselector, power measurement is made only of the displayed signal, not of its harmonics or other signals present. Thus you can simultaneously measure and display both frequency and power of individual signals in a multisignal environment. Easy keystroke entry of power offsets can be used to measure power deviation from a reference, or to compensate for losses in external hook-ups such as cable and attenuator losses.

Proven Reliability

This counter has become the standard in reliability, achieving over 26,000 hours (12.5 years) of field-proven MTBF. The high performance, economy and compact configuration of the 545B and 548B make them the ideal choice for your production and R&D applications on the bench.