Haofan Cai | Yao Zheng@UHM

Optimized IRS Positioning for Phase-Tuned Wireless Physiological Motion Detection

Mon, 10 Nov 2025 00:00:00 +0000

Secure-IRS: Defending Against Adversarial Physical-Layer Sensing in ISAC System

Mon, 10 Nov 2025 00:00:00 +0000

Drone-Mounted mmWave Harmonic Radar for Invasive Insect Monitoring

Fri, 07 Nov 2025 00:00:00 -1000

Executive Summary

This project develops an innovative drone-mounted millimeter-wave (mmWave) harmonic radar system for tracking invasive pest insects in Hawai‘i. The technology targets destructive species such as the coconut rhinoceros beetle and melon fly, aiming to improve early detection, optimize control strategies, and protect the islands’ ecosystems and agriculture.

Traditional harmonic radar systems are limited to short ranges and heavy transponders. Our approach integrates 12 GHz/24 GHz phased-array beamforming, miniaturized Nitinol-based transponders, and multi-drone coordination for long-range, real-time tracking of small, fast-moving insects—achieving high precision with minimal behavioral impact.

Research Objectives

Goal: Build and validate a UAV-mounted harmonic radar network for aerial tracking of invasive insects across complex Hawaiian landscapes.

Task 1 – mmWave Beamsteering Harmonic Transceiver

Design a compact 12 GHz phased-array transmitter using COTS modules and a heterodyne architecture for coherent beamforming.

Operates at 12/24 GHz ISM bands
Achieves >10 m range with lightweight, steerable arrays
Enables UAV integration for agile tracking

Task 2 – Ultralight Harmonic Tag

Develop a miniaturized 24 GHz transponder using a hollow bowtie antenna made of shape-memory alloy (Nitinol) and a Schottky diode for harmonic generation.

Tag weight < 1 mg for compatibility with small insects
Structural resilience through Nitinol’s superelasticity
Broadband harmonic reflection optimized for 12→24 GHz doubling

Task 3 – Multi-Drone Localization Network

Implement a distributed multistatic radar system using one TX and multiple RX drones for real-time localization.

Uses synchronized bistatic ranging and multilateration
Integrates GPS time sync and low-latency communications
Coordinates drone formations for continuous insect tracking

Broader Impacts

This system aligns with HISC priorities for early detection and rapid response (Priority 1) and technological innovation for pest management (Priority 2). It promotes cross-disciplinary collaboration among engineers, biologists, and agricultural scientists to create deployable surveillance tools for invasive species control.
Potential benefits include:

Reduced pesticide dependence through precise targeting
Enhanced monitoring of remote or forested regions
Scalable open-source framework for ecological sensing

Team

PI: Dr. Yao Zheng – mmWave radar, phased array, RF sensing
Co-PI: Dr. Haofan Cai – RFID and low-power tag design
Co-PI: Dr. Daniel Jenkins – UAV systems, autonomous sensing, precision agriculture

Collaborators include USDA-PBARC and NIWC Pacific for field validation and data integration.

Timeline (Dec 2025 – Nov 2026)

Phase	Period	Milestone	Lead
Phase I	Months 1–3	Frequency translator upgrade and system specification	UHM ECE
Phase II	Months 4–6	Phased-array prototype and beamforming validation	UHM ECE
Phase III	Months 7–9	Harmonic tag fabrication and field characterization	UHM ECE
Phase IV	Months 10–12	Multi-drone localization demo and final reporting	UHM ECE

Expected Deliverables

Functional 12/24 GHz drone-mounted harmonic radar prototype
Miniaturized Nitinol-based insect tags (< 1 mg)
Validated multi-drone localization system (> 100 m effective range)
Technical documentation and open-source dataset for future HISC programs

📡 Project Lead:
🏛️ Institution: University of Hawai‘i at Mānoa – College of Engineering
🌺 Supported by: Hawai‘i Invasive Species Council (HISC) 2026–2027

RASRE: Reflectarray and Applications in Smart Radio Environment

Tue, 10 Dec 2024 00:00:00 -1000

Executive Summary

Reflectarray present a paradigm shift in wireless communication and sensing in mmWave and sub-THz region by offering unprecedented control over the propagation environment. Traditional wireless systems are largely at the mercy of the channel, which can be severely impaired by obstacles, fading, and interference. Reflectarray, however, introduce a new degree of freedom by enabling programmable manipulation of the wireless channel. Through precise control of the reflection and refraction properties of an array of elements, reflectarray can be used to mitigate path loss, combat fading, null interference, and shape radiation patterns, which can be used to enhancing spectral efficiency, energy efficiency, and expanding coverage. This project aims to investigate the fundamental principles of reflectarray operation, develop novel reflectarray architectures and control algorithms, and explore their applications in a wide range of wireless communication, sensing, energy transfer, and security scenarios.

Logistics

CRN

Semester ENGR196 ENGR296 ENGR396 ECE496

Spring 2025 TBD TBD TBD TBD
Personnel

Advisor Office Hours

Yao Zheng

Email with ‘’[VIP RASRE]’’ in the subject line.

See
Meeting:

Time Location

TBD HH488, Zoom
Workload

ENGR196 ENGR296 ENGR396 EE496¹ Deliverables²

$ \geq $ 3 H/W $ \geq $ 3 H/W $ \geq $ 6 H/W $ \geq $ 8 H/W

One per group

Indicate the authors of the appropriate sections.

Semester	ENGR196	ENGR296	ENGR396	ECE496
Spring 2025	TBD	TBD	TBD	TBD

Advisor	Office Hours
Yao Zheng Email with ‘’[VIP RASRE]’’ in the subject line.	See

Time	Location
TBD	HH488, Zoom

ENGR196	ENGR296	ENGR396	EE496¹	Deliverables²
$ \geq $ 3 H/W	$ \geq $ 3 H/W	$ \geq $ 6 H/W	$ \geq $ 8 H/W	One per group Indicate the authors of the appropriate sections.

Grading

General Breakdown

Category	Portion of Grade
1- Quality of project work Engagement, pursuit of knowledge necessary for project, contributions to technical progress of project, (396 and 496: contributions to management of project).	35%
2- Documentation and records Design notebook, wiki documentation, presentations, Reports.	35%
3- Teamwork and interaction Attendance to meetings, contributions to team, peer evaluations, team presentations and reports	30%

Breakdown by Deliverable

Deliverable	ENGR 196/296/396	EE496/499	Applicable Categories
Project proposal report	10%	10%	1,2,3
Preliminary design review presentation	15%	20%	1,2,3
Design notebook check	10%	5%	1,2
VIP poster session presentation	10%	15%	1,2,3
Final report draft (proofed by peers)	N/A	N/A	1,2,3
Final recorded video presentation	20%	25%	1,2,3
Final report	25%	15%	1,2,3
Design notebook final check	10%	10%	1,2

Cutoffs

A- B- C-

70% 50% 30%

A-	B-	C-
70%	50%	30%

Iterations

SEMESTER	TOPICS	DOCUMENTS
Spring, 2025	Designing 3.5GHz reflectarray with transistors

This course adheres to UH Manoa W focus requirements and ECE Department requirements. So you are required to write 4,000 words or more throughout the semester, split between the proposal and the final report. ↩︎
Reports should be uploaded to the Google Drive before the deadline. Late reports are subject to a minimum 15% reduction in grade. Presentation files (PowerPoint or PDF) should be uploaded to the Google Drive before or immediately after your presentation. ↩︎