Transmit Filter for Duplexer/Diplexer Systems | Specifications & Verification

Product Specifications

Technical details and manufacturing context for Transmit Filter

Definition

The transmit filter is a critical component in duplexer/diplexer systems used in communication equipment. It functions as a bandpass filter specifically tuned to the transmit frequency band, allowing the outgoing transmission signals to pass through with minimal attenuation while providing high rejection of receive band signals and other unwanted frequencies. This prevents transmitter noise from interfering with the receiver and ensures efficient signal transmission. The filter is designed for use in full-duplex communication systems where simultaneous transmission and reception are required. It is typically implemented using cavity resonators, dielectric resonators, or surface acoustic wave (SAW) technology, depending on the application's frequency and power requirements. The transmit filter is characterized by parameters such as center frequency, bandwidth, insertion loss, return loss, attenuation at the receive band, power handling, impedance, operating temperature, storage temperature, humidity, dimensions, and weight. These parameters are provided as reference ranges and must be verified for the specific model and application. The filter is constructed from materials such as aluminum alloy, dielectric ceramic, copper, and silver plating, which contribute to its performance and durability. It is intended for use in communication equipment and is not a standalone product; it must be integrated into a duplexer or diplexer system. When selecting a transmit filter, it is important to consider the specific frequency band, bandwidth, power handling, and environmental conditions of the application. Verification with the manufacturer or supplier is essential to ensure the filter meets the required specifications and standards. The filter's performance can degrade over time due to environmental factors, mechanical stress, or component aging, so regular inspection and testing are recommended. Failure to maintain proper operation may result in increased insertion loss, reduced isolation, or complete failure of the duplexer system.

Working Principle

The transmit filter operates on electromagnetic resonance principles, typically using cavity resonators, dielectric resonators, or surface acoustic wave (SAW) technology. It creates a frequency-selective path that exhibits low insertion loss within the designated transmit frequency band while providing high attenuation (isolation) outside this band, particularly in the receive frequency range. This frequency discrimination enables simultaneous transmission and reception in full-duplex communication systems.

Common Materials

Aluminum alloy, Dielectric ceramic, Copper, Silver plating

Technical Parameters

Parameter	Typical range	Notes & selection driver
Center Frequency	1.8–2.2 GHz	Defines the transmit band center.
Bandwidth	60–100 MHz	Passband width for transmit signal.
Insertion Loss	≤1.5 dB	Lower is better for efficiency.
Return Loss	≥18 dB	Impedance matching quality.
Attenuation at Receive Band	≥50 dB	Rejects receive signals.
Power Handling	30–50 W	Continuous wave power.
Impedance	50 Ω	Standard system impedance.
Operating Temperature	-40–85 °C	Full performance range.
Storage Temperature	-55–125 °C	Non-operating survival.
Humidity	0–95 % RH	Non-condensing.
Dimensions	20×15×5 mm	Typical SMT package.
Weight	≤5 g	Lightweight for portability.

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Components / BOM

Resonator Cavity
Creates electromagnetic resonance at specific frequencies

Material: Aluminum alloy with silver plating
Coupling Mechanism
Controls energy transfer between resonators

Material: Copper tuning screws
Input/Output Port Part
Signal connection interface

Material: Gold-plated connectors
Housing Part
Provides mechanical protection and shielding

Material: Aluminum alloy
Dielectric Resonator Optional
Sets the passband in a much smaller volume than a metal cavity.
Surface Acoustic Wave Resonator Optional
Does the same job on a piezo chip for small, high-volume radios.

Applied To / Applications

This component is essential for the following industrial systems and equipment:

Duplexer/Diplexer

View system integration details

Manufacturers of Transmit Filter

Manufacturer profiles associated with Transmit Filter.

Sourcing Transmit Filter from China?

Tell us your specification and target quantity — we will match it against manufacturer records and come back with the factories that fit.

Request manufacturers We manufacture this

Manufacturer listings support early research and capability understanding. They are not certification, ranking, or transaction guarantees.

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation

Request current drawings, revision history, and a signed specification sheet.

Manufacturing capability

Verify equipment lists, process limits, capacity, and representative production evidence.

Inspection readiness

Confirm test methods, calibrated equipment, sampling plans, and traceable reports.

Supplier transparency

Check the legal entity, factory address, ownership, certifications, and direct contacts.

CNFX does not score or rank suppliers. Buyers must verify all claims and documents with the legal manufacturer before ordering.

Frequently Asked Questions

What is the primary function of a transmit filter?

The transmit filter selectively passes signals in the transmit frequency band while rejecting receive band signals and other interference, preventing transmitter noise from interfering with the receiver.

What technologies are commonly used in transmit filters?

Common technologies include cavity resonators, dielectric resonators, and surface acoustic wave (SAW) devices, each offering different trade-offs in size, performance, and power handling.

How do I verify that a transmit filter meets my requirements?

You must check the filter's specifications, such as center frequency, bandwidth, insertion loss, and power handling, against your application needs. Always confirm model-specific values with the manufacturer or supplier.

What are typical materials used in transmit filters?

Typical materials include aluminum alloy, dielectric ceramic, copper, and silver plating, which are chosen for their electrical and mechanical properties.

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records.

Preliminary Technical Classification

This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

Buyer enquiry

Request manufacturing insight for Transmit Filter

Ask for use case, specification boundaries, supplier type, and RFQ preparation information for this product.

Where it goes: Straight to the CNFX editorial desk, and to the manufacturer if this product is linked to a claimed profile. Nothing is broadcast to a supplier list.
Your details stay here: We do not sell or rent enquiry data, and we do not add you to a mailing list. Used only to answer this request.
No commission, no middleman: CNFX is a directory. We take no cut of any order and never negotiate on a supplier's behalf.
What we don't claim: A listing is not an endorsement. Qualify every supplier and verify every figure yourself before ordering.

pressure:	Atmospheric to 2 bar
other spec:	Frequency Range: 1.8-2.2 GHz, Insertion Loss: <1.5 dB, Rejection: >40 dB at receive band
temperature:	-40°C to +85°C

Transmit Filter

Product Specifications

Applied To / Applications

Industrial Ecosystem & Supply Chain Structure

Application Fit & Sizing Matrix

Reliability & Engineering Risk Analysis

Compliance & Manufacturing Standards